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14541867
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Chlorogenate—glucarate O-hydroxycinnamoyltransferase
|
In enzymology, a chlorogenate-glucarate O-hydroxycinnamoyltransferase (EC 2.3.1.98) is an enzyme that catalyzes the chemical reaction
chlorogenate + glucarate formula_0 quinate + 2-O-caffeoylglucarate
Thus, the two substrates of this enzyme are chlorogenate and glucarate, whereas its two products are quinate and 2-O-caffeoylglucarate.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is chlorogenate:glucarate O-(hydroxycinnamoyl)transferase. Other names in common use include chlorogenate:glucarate caffeoyltransferase, chlorogenic acid:glucaric acid O-caffeoyltransferase, and chlorogenate:glucarate caffeoyltransferase.
References.
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https://en.wikipedia.org/wiki?curid=14541867
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14541882
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Citrate (Re)-synthase
|
In enzymology, a citrate (Re)-synthase (EC 2.3.3.3) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + H2O + oxaloacetate formula_0 citrate + CoA
The 3 substrates of this enzyme are acetyl-CoA, H2O, and oxaloacetate, whereas its two products are citrate and CoA.
This enzyme belongs to the family of transferases, specifically those acyltransferases that convert acyl groups into alkyl groups on transfer. The systematic name of this enzyme class is acetyl-CoA:oxaloacetate C-acetyltransferase [thioester-hydrolysing, (pro-R)-carboxymethyl-forming]. Other names in common use include (R)-citrate synthase, Re-citrate-synthase, and citrate oxaloacetate-lyase [(pro-3R)-CH2COO→acetyl-CoA].
References.
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https://en.wikipedia.org/wiki?curid=14541882
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14541908
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Cortisol O-acetyltransferase
|
Enzyme
In enzymology, a cortisol O-acetyltransferase (EC 2.3.1.27) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + cortisol formula_0 CoA + cortisol 21-acetate
Thus, the two substrates of this enzyme are acetyl-CoA and cortisol, whereas its two products are CoA and cortisol 21-acetate.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:cortisol O-acetyltransferase. Other names in common use include cortisol acetyltransferase, corticosteroid acetyltransferase, and corticosteroid-21-O-acetyltransferase.
References.
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https://en.wikipedia.org/wiki?curid=14541908
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14541919
|
Cysteine-S-conjugate N-acetyltransferase
|
In enzymology, a cysteine-S-conjugate N-acetyltransferase (EC 2.3.1.80) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + an S-substituted L-cysteine formula_0 CoA + an S-substituted N-acetyl-L-cysteine
Thus, the two substrates of this enzyme are acetyl-CoA and S-substituted L-cysteine, whereas its two products are CoA and S-substituted N-acetyl-L-cysteine.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:S-substituted L-cysteine N-acetyltransferase. This enzyme participates in glutathione metabolism.
References.
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https://en.wikipedia.org/wiki?curid=14541919
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14541927
|
D-alanine gamma-glutamyltransferase
|
In enzymology, a D-alanine gamma-glutamyltransferase (EC 2.3.2.14) is an enzyme that catalyzes the chemical reaction
L-glutamine + D-alanine formula_0 NH3 + gamma-L-glutamyl-D-alanine
Thus, the two substrates of this enzyme are L-glutamine and D-alanine, whereas its two products are NH3 and gamma-L-glutamyl-D-alanine.
This enzyme belongs to the family of transferases, specifically the aminoacyltransferases. The systematic name of this enzyme class is L-glutamine:D-alanine gamma-glutamyltransferase.
References.
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https://en.wikipedia.org/wiki?curid=14541927
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14541940
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D-amino-acid N-acetyltransferase
|
In enzymology, a D-amino-acid N-acetyltransferase (EC 2.3.1.36) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + a D-amino acid formula_0 CoA + an N-acetyl-D-amino acid
Thus, the two substrates of this enzyme are acetyl-CoA and D-amino acid, whereas its two products are CoA and N-acetyl-D-amino acid.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:D-amino-acid N-acetyltransferase. Other names in common use include D-amino acid acetyltransferase, and D-amino acid-alpha-N-acetyltransferase. This enzyme participates in phenylalanine metabolism.
References.
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https://en.wikipedia.org/wiki?curid=14541940
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14541953
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Deacetylcephalosporin-C acetyltransferase
|
In enzymology, a deacetylcephalosporin-C acetyltransferase (EC 2.3.1.175) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + deacetylcephalosporin C formula_0 CoA + cephalosporin C
Thus, the two substrates of this enzyme are acetyl-CoA and deacetylcephalosporin C, whereas its two products are CoA and cephalosporin C.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:deacetylcephalosporin-C O-acetyltransferase. Other names in common use include acetyl-CoA:deacetylcephalosporin-C acetyltransferase, DAC acetyltransferase, cefG, deacetylcephalosporin C acetyltransferase, acetyl coenzyme A:DAC acetyltransferase, acetyl-CoA:DAC acetyltransferase, CPC acetylhydrolase, acetyl-CoA:DAC O-acetyltransferase, and DAC-AT. This enzyme participates in penicillin and cephalosporin biosynthesis.
References.
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https://en.wikipedia.org/wiki?curid=14541953
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14541971
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Deacetyl-(citrate-(pro-3S)-lyase) S-acetyltransferase
|
In enzymology, a deacetyl-[citrate-(pro-3S)-lyase] S-acetyltransferase (EC 2.3.1.49) is an enzyme that catalyzes the chemical reaction
S-acetylphosphopantetheine + deacetyl-[citrate-oxaloacetate-lyase((pro-3S)-CH2COO-->acetate)] formula_0 phosphopantetheine + [citrate-oxaloacetate-lyase((pro-3S)-CH2COO-->acetate)]
Thus, the two substrates of this enzyme are S-acetylphosphopantetheine and deacetyl-[citrate-oxaloacetate-lyase((pro-3S)-CH2COO-->acetate)], whereas its two products are phosphopantetheine and citrate-oxaloacetate-lyase((pro-3S)-CH2COO-->acetate).
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is S-acetylphosphopantetheine:deacetyl-[citrate-oxaloacetate-lyase((pro -3S)-CH2COO-->acetate)] S-acetyltransferase. Other names in common use include S-acetyl phosphopantetheine:deacetyl citrate lyase, S-acetyltransferase, and deacetyl-[citrate-(pro-3S)-lyase] acetyltransferase.
References.
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https://en.wikipedia.org/wiki?curid=14541971
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14541986
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Deacetylvindoline O-acetyltransferase
|
In enzymology, a deacetylvindoline O-acetyltransferase (EC 2.3.1.107) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + deacetylvindoline formula_0 CoA + vindoline
Thus, the two substrates of this enzyme are acetyl-CoA and deacetylvindoline, whereas its two products are CoA and vindoline.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:deacetylvindoline 4-O-acetyltransferase. Other names in common use include deacetylvindoline acetyltransferase, DAT, 17-O-deacetylvindoline-17-O-acetyltransferase, acetylcoenzyme A-deacetylvindoline 4-O-acetyltransferase, acetyl-CoA-17-O-deacetylvindoline 17-O-acetyltransferase, acetylcoenzyme A:deacetylvindoline 4-O-acetyltransferase, acetylcoenzyme A:deacetylvindoline O-acetyltransferase, 17-O-deacetylvindoline O-acetyltransferase, and acetyl-CoA:17-O-deacetylvindoline 17-O-acetyltransferase. This enzyme participates in terpene indole and ipecac alkaloid biosynthesis.
References.
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https://en.wikipedia.org/wiki?curid=14541986
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14541994
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Decylcitrate synthase
|
Decylcitrate synthase (EC 2.3.3.2) is an enzyme that catalyzes the chemical reaction in enzymology.
lauroyl-CoA + H2O + oxaloacetate formula_0 (2S,3S)-2-hydroxytridecane-1,2,3-tricarboxylate + CoA
The 3 substrates of this enzyme are lauroyl-CoA, H2O, and oxaloacetate, whereas its two products are (2S,3S)-2-hydroxytridecane-1,2,3-tricarboxylate and CoA.
This enzyme belongs to the family of transferases, specifically those acyltransferases that convert acyl groups into alkyl groups on transfer. The systematic name of this enzyme class is dodecanoyl-CoA:oxaloacetate C-dodecanoyltransferase (thioester-hydrolysing, 1-carboxyundecyl-forming). Other names in common use include 2-decylcitrate synthase, (2S,3S)-2-hydroxytridecane-1,2,3-tricarboxylate oxaloacetate-lyase, and (CoA-acylating).
References.
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https://en.wikipedia.org/wiki?curid=14541994
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14542015
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Decylhomocitrate synthase
|
In enzymology, a decylhomocitrate synthase (EC 2.3.3.4) is an enzyme that catalyzes the chemical reaction
dodecanoyl-CoA + H2O + 2-oxoglutarate formula_0 (3S,4S)-3-hydroxytetradecane-1,3,4-tricarboxylate + CoA
The 3 substrates of this enzyme are dodecanoyl-CoA, H2O, and 2-oxoglutarate, whereas its two products are (3S,4S)-3-hydroxytetradecane-1,3,4-tricarboxylate and CoA.
This enzyme belongs to the family of transferases, specifically those acyltransferases that convert acyl groups into alkyl groups on transfer. The systematic name of this enzyme class is dodecanoyl-CoA:2-oxoglutarate C-dodecanoyltransferase (thioester-hydrolysing, 1-carboxyundecyl-forming). Other names in common use include 2-decylhomocitrate synthase, 3-hydroxytetradecane-1,3,4-tricarboxylate 2-oxoglutarate-lyase, and (CoA-acylating).
References.
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https://en.wikipedia.org/wiki?curid=14542015
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14542027
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D-glutamyltransferase
|
In enzymology, a D-glutamyltransferase (EC 2.3.2.1) is an enzyme that catalyzes the chemical reaction
L(or D)-glutamine + D-glutamyl-peptide formula_0 NH3 + 5-glutamyl-D-glutamyl-peptide
The 3 substrates of this enzyme are L-glutamine, D-glutamine, and D-glutamyl-peptide, whereas its two products are NH3 and 5-glutamyl-D-glutamyl-peptide.
This enzyme belongs to the family of transferases, specifically the aminoacyltransferases. The systematic name of this enzyme class is glutamine:D-glutamyl-peptide 5-glutamyltransferase. Other names in common use include D-glutamyl transpeptidase, and D-gamma-glutamyl transpeptidase. This enzyme participates in d-glutamine and d-glutamate metabolism.
References.
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https://en.wikipedia.org/wiki?curid=14542027
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14542042
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Diacylglycerol—sterol O-acyltransferase
|
In enzymology, a diacylglycerol-sterol O-acyltransferase (EC 2.3.1.73) is an enzyme that catalyzes the chemical reaction
1,2-diacyl-sn-glycerol + sterol formula_0 monoacylglycerol + sterol ester
Thus, the two substrates of this enzyme are 1,2-diacyl-sn-glycerol and sterol, whereas its two products are monoacylglycerol and sterol ester.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is 1,2-diacyl-sn-glycerol:sterol O-acyltransferase. This enzyme is also called 1,2-diacyl-sn-glycerol:sterol acyl transferase. This enzyme participates in bile acid biosynthesis.
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https://en.wikipedia.org/wiki?curid=14542042
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14542053
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Diamine N-acetyltransferase
|
In enzymology, a diamine N-acetyltransferase (EC 2.3.1.57) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + an alkane-alpha,omega-diamine formula_0 CoA + an N-acetyldiamine
Thus, the two substrates of this enzyme are acetyl-CoA and alkane-alpha,omega-diamine, whereas its two products are CoA and N-acetyldiamine.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:alkane-alpha,omega-diamine N-acetyltransferase. Other names in common use include spermidine acetyltransferase, putrescine acetyltransferase, putrescine (diamine)-acetylating enzyme, diamine acetyltransferase, spermidine/spermine N1-acetyltransferase, spermidine N1-acetyltransferase, acetyl-coenzyme A-1,4-diaminobutane N-acetyltransferase, putrescine acetylase, and putrescine N-acetyltransferase. This enzyme participates in urea cycle and metabolism of amino groups.
Structural studies.
As of late 2007, 12 structures have been solved for this class of enzymes, with PDB accession codes 2B3U, 2B3V, 2B4B, 2B4D, 2B58, 2B5G, 2BEI, 2F5I, 2FXF, 2G3T, 2JEV, and 2Q4V.
References.
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14542066
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Diaminobutyrate acetyltransferase
|
In enzymology, a diaminobutyrate acetyltransferase (EC 2.3.1.178) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + L-2,4-diaminobutanoate formula_0 CoA + N4-acetyl-L-2,4-diaminobutanoate
Thus, the two substrates of this enzyme are acetyl-CoA and L-2,4-diaminobutanoate, whereas its two products are CoA and N4-acetyl-L-2,4-diaminobutanoate.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:L-2,4-diaminobutanoate N4-acetyltransferase. Other names in common use include L-2,4-diaminobutyrate acetyltransferase, L-2,4-diaminobutanoate acetyltransferase, EctA, diaminobutyric acid acetyltransferase, DABA acetyltransferase, 2,4-diaminobutanoate acetyltransferase, DAB acetyltransferase, DABAcT, and acetyl-CoA:L-2,4-diaminobutanoate 4-N-acetyltransferase. This enzyme participates in glycine, serine and threonine metabolism.
References.
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https://en.wikipedia.org/wiki?curid=14542066
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14542081
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Dihydrolipoyllysine-residue (2-methylpropanoyl)transferase
|
In enzymology, a dihydrolipoyllysine-residue (2-methylpropanoyl)transferase (EC 2.3.1.168) is an enzyme that catalyzes the chemical reaction
2-methylpropanoyl-CoA + enzyme N6-(dihydrolipoyl)lysine formula_0 CoA + enzyme N6-(S-[2-methylpropanoyl]dihydrolipoyl)lysine
Thus, the two substrates of this enzyme are 2-methylpropanoyl-CoA and enzyme N6-(dihydrolipoyl)lysine, whereas its two products are CoA and enzyme N6-(S-[2-methylpropanoyl]dihydrolipoyl)lysine.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is 2-methylpropanoyl-CoA:enzyme-N6-(dihydrolipoyl)lysine S-(2-methylpropanoyl)transferase. Other names in common use include dihydrolipoyl transacylase, enzyme-dihydrolipoyllysine:2-methylpropanoyl-CoA, S-(2-methylpropanoyl)transferase, 2-methylpropanoyl-CoA:enzyme-6-N-(dihydrolipoyl)lysine, and S-(2-methylpropanoyl)transferase. This enzyme participates in valine, leucine and isoleucine degradation.
Structural studies.
As of late 2007, 6 structures have been solved for this class of enzymes, with PDB accession codes 1ZWV, 2COO, 2IHW, 2II3, 2II4, and 2II5.
References.
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https://en.wikipedia.org/wiki?curid=14542081
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14542113
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Dihydrolipoyllysine-residue succinyltransferase
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In enzymology, a dihydrolipoyllysine-residue succinyltransferase (EC 2.3.1.61) is an enzyme that catalyzes the chemical reaction
succinyl-CoA + enzyme N6-(dihydrolipoyl)lysine formula_0 CoA + enzyme N6-(S-succinyldihydrolipoyl)lysine
Thus, the two substrates of this enzyme are succinyl-CoA and enzyme N6-(dihydrolipoyl)lysine, whereas its two products are CoA and enzyme N6-(S-succinyldihydrolipoyl)lysine.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is succinyl-CoA:enzyme-N6-(dihydrolipoyl)lysine S-succinyltransferase. Other names in common use include dihydrolipoamide S-succinyltransferase, dihydrolipoamide succinyltransferase, dihydrolipoic transsuccinylase, dihydrolipolyl transsuccinylase, dihydrolipoyl transsuccinylase, lipoate succinyltransferase (Escherichia coli), lipoic transsuccinylase, lipoyl transsuccinylase, succinyl-CoA:dihydrolipoamide S-succinyltransferase, succinyl-CoA:dihydrolipoate S-succinyltransferase, and enzyme-dihydrolipoyllysine:succinyl-CoA S-succinyltransferase. This enzyme participates in citrate cycle (tca cycle) and lysine degradation.
Structural studies.
As of late 2007, 11 structures have been solved for this class of enzymes, with PDB accession codes 1BAL, 1BBL, 1C4T, 1E2O, 1GHJ, 1GHK, 1PMR, 1SCZ, 2BTG, 2BTH, and 2CYU.
References.
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https://en.wikipedia.org/wiki?curid=14542113
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14542131
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Dolichol O-acyltransferase
|
In enzymology, a dolichol O-acyltransferase (EC 2.3.1.123) is an enzyme that catalyzes the chemical reaction
palmitoyl-CoA + dolichol formula_0 CoA + dolichyl palmitate
Thus, the two substrates of this enzyme are palmitoyl-CoA and dolichol, whereas its two products are CoA and dolichyl palmitate.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is palmitoyl-CoA:dolichol O-palmitoyltransferase. This enzyme is also called acyl-CoA:dolichol acyltransferase.
References.
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https://en.wikipedia.org/wiki?curid=14542131
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14542151
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D-tryptophan N-acetyltransferase
|
In enzymology, a D-tryptophan N-acetyltransferase (EC 2.3.1.34) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + D-tryptophan formula_0 CoA + N-acetyl-D-tryptophan
Thus, the two substrates of this enzyme are acetyl-CoA and D-tryptophan, whereas its two products are CoA and N-acetyl-D-tryptophan.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:D-tryptophan N-acetyltransferase. Other names in common use include D-tryptophan acetyltransferase, and acetyl-CoA-D-tryptophan-alpha-N-acetyltransferase.
References.
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14542164
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D-tryptophan N-malonyltransferase
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In enzymology, a D-tryptophan N-malonyltransferase (EC 2.3.1.112) is an enzyme that catalyzes the chemical reaction
malonyl-CoA + D-tryptophan formula_0 CoA + N2-malonyl-D-tryptophan
Thus, the two substrates of this enzyme are malonyl-CoA and D-tryptophan, whereas its two products are CoA and N2-malonyl-D-tryptophan.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is malonyl-CoA:D-tryptophan N-malonyltransferase.
References.
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https://en.wikipedia.org/wiki?curid=14542164
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14542183
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Ecdysone O-acyltransferase
|
In enzymology, an ecdysone O-acyltransferase (EC 2.3.1.139) is an enzyme that catalyzes the chemical reaction
palmitoyl-CoA + ecdysone formula_0 CoA + ecdysone palmitate
Thus, the two substrates of this enzyme are palmitoyl-CoA and ecdysone, whereas its two products are CoA and ecdysone palmitate.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is palmitoyl-CoA:ecdysone palmitoyltransferase. Other names in common use include acyl-CoA:ecdysone acyltransferase, and fatty acyl-CoA:ecdysone acyltransferase.
References.
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https://en.wikipedia.org/wiki?curid=14542183
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14542198
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Erythronolide synthase
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In enzymology, an erythronolide synthase (also 6-Deoxyerythronolide B Synthase or DEBS) is an enzyme that catalyzes the chemical reaction
6 malonyl-CoA + propanoyl-CoA formula_0 7 CoA + 6-deoxyerythronolide B
Thus, the two substrates of this enzyme are malonyl-CoA and propanoyl-CoA, whereas its two products are CoA and 6-deoxyerythronolide b. This enzyme participates in biosynthesis of 12-, 14- and 16-membered macrolides.
This enzyme belongs to the family of transferases, it has been identified as part of a Type 1 polyketide synthase module. DEBS is found in "Saccharopolyspora erythraea" and other actinobacteria, and is responsible for the synthesis of the macrolide ring which is the precursor of the antibiotic erythromycin. There have been three categories of polyketide synthases identified to date, type 1, 2 and 3. Type one synthases involve large multidomain proteins containing all the sites necessary for polyketide synthesis. Type two synthases contain active sites distributed among several smaller polypeptides, and type three synthases are large multi-protein complexes containing modules which have a single active site for each and every step of polyketide synthesis. In the case of DEBS, there are three large multi-functional proteins, DEBS 1,2, and 3, that each exist as a dimer of two modules. Each module consists of a minimum of a Ketosynthase (KS), Acyl carrier protein (ACP) site, and acyltransferase (AT), but may also contain a Ketoreductase (KR), Dehydrotase (DH), and Enol Reductase (ER) for additional reduction reactions. The DEBS complex also contains a Loading Domain on module 1 consisting of an acyl carrier protein and an acyltransferase. The terminal Thioesterase acts solely to terminate DEBS polyketide synthesis and cyclize the macrolide ring.
Module components and functions.
Ketosynthase.
The active site of this enzyme has a very broad specificity, which allows for the synthesis of long chains of carbon atoms by joining, via a thioester linkage, small organic acids, such as acetic and malonic acid. The KS domain receives the growing polyketide chain from the upstream module and subsequently catalyzes formation of the C-C bond between this substrate and an ACP-bound extender unit that is selected by the AT domain.
Acyltransferase.
Each AT domain has an α-carboxylated CoA thioester (i.e. methylmalonyl-CoA) This specificity prevents non-essential addition of enzymes within the module. The AT captures a nucleophilic β-carboxyacyl-CoA extender unit and transfers it to the phosphopantetheine arm of the ACP domain.
Functions via catalyzing acyl transfer from methylmalonyl-CoA to the ACP domain within the same module via a covalent acyl-AT intermediate. The importance of the AT to the stringent incorporation of specific extender unit in the synthesis of polyketide building blocks makes it vital that the mechanism and structure of these domains be well-elucidated in order to develop efficient strategies for the regiospecific engineering of extender unit incorporation in polyketide biosynthesis.
Acyl Carrier Protein.
The ACP is not substrate specific, which allows for the interaction with every domain present within its module. This protein collaborates with the ketosynthase (KS) domain of the same module to catalyze polyketide chain elongation, and subsequently engages with the KS domain of the next module to facilitate forward chain transfer. The ACP first accepts the extender unit from the AT, then collaborates with the KS domain in chain elongation, and finally anchors the newly elongated chain as it undergoes modification at the β-keto position. In order to carry out their function, the ACP domains require post-translational addition of a phosphopantetheine group to a conserved serine residue of the ACP. The terminal sulfhydryl group of the phosphopantetheine is the site of attachment of the growing polyketide chain.
Thioesterase.
Located at the C-terminus site of the furthest downstream module. It is terminated in a thioesterase, which releases the mature polyketide (either as the free acid or a cyclized product), via lactonization.
Note: As stated above, the first module of DEBS contains an additional acyltransferase and ACP for initiation of the reactions
Non-essential components.
Additional components, may have any one or a combination of the following:
Ketoreductase- Uses NADPH to stereospecifically reduce it to a hydroxyl group
Dehydratase- Catalyzes the removal of the hydroxyl group to create a double bond from organic compounds in the form of water
Enolreductase- Utilizes NADPH to reduce the double bond from the organic compound
Comparison between fatty acid synthesis and polyketide synthesis.
Fatty acid synthesis in most prokaryotes occurs by a type II synthase made of many enzymes located in the cytoplasm that can be separated. However, some bacteria such as Mycobacterium smegmatis as well as mammals and yeast use a type I synthase which is a large multifunctional protein similar to the synthase used for polyketide synthesis. This Type I synthase includes discrete domains on which individual reactions are catalyzed.
In both fatty acid synthesis and polyketide synthesis, the intermediates are covalently bound to ACP, or acyl carrier protein. However, in fatty acid synthesis the original molecules are Acyl-CoA or Malonyl-CoA but polyketide synthases can use multiple primers including acetyl-CoA, propionyl-CoA, isobutyryl-CoA, cyclohexanoyl-CoA, 3-amino-5-hydroxybenzoyl-CoA, or cinnamyl-CoA. In both fatty acid synthesis and polyketide synthesis these CoA carriers will be exchanged for ACP before they are incorporated into the growing molecule.
During the elongation steps of fatty acid synthesis, ketosynthase, ketoreductase, dehydratase, and enoylreductase are all used in sequence to create a saturated fatty acid then postsynthetic modification can be done to create an unsaturated or cyclo fatty acid. However, in polyketide synthesis these enzymes can be used in different combinations to create segments of polyketide that are saturated, unsaturated, or have a hydroxyl or carbonyl functional group. There are also enzymes used in both fatty acid synthesis and polyketide synthesis that can make modifications to the molecule after it has been synthesized.
As far as regulating the length of the molecule being synthesized, the specific mechanism by which fatty acid chain length remains unknown but it is expected that ACP-bound fatty acid chains of the correct length act as allosteric inhibitors of the fatty acid synthesis enzymes. In polyketide synthesis, the synthases are composed of modules in which the order of enzymatic reactions is defined by the structure of the protein complex. This means that once the molecule reaches the last reaction of the last module, the polyketide is released from the complex by a thioesterase enzyme. Therefore, regulation of fatty acid chain length is most likely due to allosteric regulation, and regulation of polyketide length is due to a specific enzyme within the polyketide synthase.
Application.
Since the late 1980s and early 1990s research on polyketide synthases (PKS), a number of strategies for the genetic modification of such PKS have been developed and elucidated. Such changes in PKS are of particular interest to the pharmaceutical industry as new compounds with antibiotic or other antimicrobial effects are commonly synthesized after changes to the structure of the PKS have been made. Engineering the PKS complex is a much more practical method than synthesizing each product via chemical reactions in vitro due to the cost of reagents and the number of reactions that must take place. Just to exemplify the potential rewards of synthesizing new and effective antimicrobials, in 1995, the worldwide sales of erythromycin and its derivatives exceeded 3.5 billion dollars. This portion will examine the modifications of structure in the DEBS PKS to create new products in regards to erythromycin derivatives as well as completely new polyketides generated by various means of engineering the modular complex.
There are five general methods in which DEBS is regularly modified:
Deletion or inactivation of active sites and modules.
The first reported instance of genetic engineering of DEBS came in 1991 from the Katz group who deleted the activity of the KR in module 5 of DEBS which produced a 5-keto macrolide instead of the usual 5-hydroxy macrolide. Since then, deletion or inactivation (often via introduction of point mutations) of many active sites to skip reduction and/or dehydration reactions have been created. Such modifications target the various KR, DH, ER active sites seen on different modules in DEBS. In fact, whole modules can be deleted in order to reduce the chain-length of the polyketides and alter the cycle of reduction/dehydration normally seen.
Substitution or addition of active sites and modules.
In one of the first reorganizations of DEBS, a copy of the terminal TE was placed at the end of each module in separate trials, which as predicted resulted in the cleavage and release of the correspondingly shortened products. Following this, ever more complex methods were devised for the addition or substitution of single or multiple active sites to the DEBS complex.
The most common method of engineering DEBS as of 2005 is AT substitution, in which the native AT domain is replaced with an AT specific for a different primer or extender molecule. Under normal circumstances, DEBS has a “loading” or priming AT specific for predominantly propionyl-CoA while all six subsequent AT are specific for the extender molecule, methylmalonyl-CoA. The native AT of DEBS have all been successfully substituted with AT from other modular PKS such as the PKS that produces rapamycin; which replaces the methylmalonyl-CoA specific AT with malonyl-CoA AT and produces a non-methylated erythromycin derivative. This mode of engineering in particular shows the versatility that can be achieved as both the priming molecule and the extender molecule can be changed to produce many new products.
In addition to the AT sites, any of the reductive/dehydrating enzyme active sites may be replaced with one or more additional reductive/dehydrating enzyme active sites. For example, in one study, the KR of module 2 of DEBS was replaced by a full set of reductive domains (DH, ER and KR) derived from module 1 of the rapamycin PKS as shown in Figure 2
FIGURE 2
There is at least one report of a whole module substitution, in which module 2 of DEBS was replaced with module 5 of the rapamycin PKS The activities of the two modules is identical, and the same erythromycin precursor (6-deoxyerythronolide B) was produced by the chimeric PKS; however, this shows the possibility of creating PKS with modules from two or even several different PKS in order to produce a multitude of new products. There is one problem with connecting heterologous modules though; there is recent evidence that the amino acid sequence between the ACP domain and the subsequent KS domain of downstream modules plays an important role in the transfer of the growing polyketide from one module to another. These regions have been labeled as “linkers” and although they have no direct catalytic role, any substitution of a linker region that is not structurally compatible with the wild-type PKS may cause poor yields of the expected product.
Precursor-directed biosynthesis.
Using a semi-synthetic approach, a diketide intermediate may be added either in vitro or in vivo to a DEBS complex in which the activity of the first KS has been deleted. This means that the diketide will load onto the second KS (in module 2 of DEBS) and be processed all the way to the end as normal. It has been shown that this second KS is fairly nonspecific and a large variety of synthetic diketides can be accepted and subsequently fully elongated and released. However, it has also been seen that this KS is not highly tolerant of structural changes at the C2 and C3 positions, especially if the stereochemistry is altered. To date, this has been the most successful approach to making macrolides with potency equal to or greater than erythromycin.
Ketoreductase replacement to alter stereospecificity.
In modular PKS, KR active sites catalyze stereospecific reduction of polyketides. Inversion of an alcohol stereocenter to the opposite stereoisomer is possible via replacement of a wild-type KR with a KR of the opposite specificity. This has rarely been done successfully, and only at the terminal KR of the DEBS complex. It has been theorized that changing the stereospecificity of a KR in an earlier module would also require the concurrent modification of all downstream KS.
Recent studies of the amino acid sequence of the two types of stereospecificity in KR have determined a perfect correlation with these residues and the predicted stereochemical outcome. This is particularly useful in situations where the gene sequence of a modular PKS is known but the final product structure has not yet been elucidated.
Tailoring enzyme modifications.
Enzymes that act on the macrolide after it has been released and cyclized by DEBS are called tailoring enzymes. Many such enzymes are involved in the production of erythromycin from the final product of unmodified DEBS, 6-deoxyerythronolide B. Such classes of enzymes include mainly oxidoreductases and glycosyl transferases and are essential for the antibiotic activity of erythromycin.
Thus far, few attempts have been made to modify tailoring pathways, however, the enzymes which participate in such pathways are currently being characterized and are of great interest. Studies are facilitated by their respective genes being located adjacent to the PKS genes, and many are therefore readily identifiable. There is no doubt that in the future, alteration of tailoring enzymes could produce many new and effective antimicrobials.
Structural studies.
As of late 2007, 8 structures have been solved for this class of enzymes, with PDB accession codes 1KEZ, 1MO2, 1PZQ, 1PZR, 2HG4, 2JU1, 2JU2, and 2QO3.
Other names of this enzyme class is malonyl-CoA:propanoyl-CoA malonyltransferase (cyclizing). Other names in common use include erythronolide condensing enzyme, and malonyl-CoA:propionyl-CoA malonyltransferase (cyclizing).
References.
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Further reading.
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https://en.wikipedia.org/wiki?curid=14542198
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14542228
|
Fatty-acyl-CoA synthase
|
Fatty-acyl-CoA synthase, or more commonly known as yeast fatty acid synthase (and not to be confused with long chain fatty acyl-CoA synthetase), is an enzyme complex responsible for fatty acid biosynthesis, and is of Type I Fatty Acid Synthesis (FAS). Yeast fatty acid synthase plays a pivotal role in fatty acid synthesis. It is a 2.6 MDa barrel shaped complex and is composed of two, unique multi-functional subunits: alpha and beta. Together, the alpha and beta units are arranged in an α6β6 structure. The catalytic activities of this enzyme complex involves a coordination system of enzymatic reactions between the alpha and beta subunits. The enzyme complex therefore consists of six functional centers for fatty acid synthesis.
Reaction.
The enzyme catalyzes the reaction:
Acetyl-CoA + n malonyl-CoA + 4n NADPH + 4n H+ formula_0 long-chain-acyl-CoA + n CoA + n CO2 + 4n NADP+
The 4 substrates of this enzyme are acetyl-CoA, malonyl-CoA, NADPH, and H+, whereas its 4 products are acyl-CoA, CoA, CO2, and NADP+.
More specifically, the FAS catalysis mechanism consumes an acetyl coenzyme A (acetyl-CoA) and seven malonyl-CoA molecules to produce a palmitoyl-CoA.
Background.
Synthesis of fatty acids is generally performed by fatty acid synthase (FAS). Though the syntheses of fatty acids are very similar across all organisms, the enzymes and subsequent enzymatic mechanisms involved in fatty acid synthesis vary between eukaryotes and prokaryotes. There are two types of fatty acid synthesis (FAS) mechanisms: type I FAS and type II FAS. Type I FAS exists in eukaryotes, including mammalian cells and fungi. Type II FAS are found in prokaryotes. The type I FAS system utilizes a multi-enzyme complex, which are highly integrated, while the type II FAS system utilizes individual, separate enzymes to catalyze the reactions involved in fatty acid synthesis. Yeast fatty acyl synthase belongs to the Type I FAS and was the first of Type I FAS to be studied.
Structure.
Yeast fatty acyl synthase, of Type I FAS, is composed of a α6β6 complex in which an αβ unit forms one functional center for fatty acid synthesis. Yeast fatty acyl synthase therefore has six reaction units for its fatty acid synthesis, in which each of these units function independently from one another. Each α and β subunit, in turn, has four functional domains, and together, the eight functional domains catalyze all the reactions of fatty acid synthesis in yeast, which includes: activation, priming, elongation, and termination. Consequently, yeast FAS is incredibly unique due to its structural complexity, which contains 48 functional centers for one α6β6 complex and can efficiently performs 6 fatty acid syntheses separately at one time.
There are seven, total enzymatic reactions in fatty acid synthesis. These reactions include: activation, priming, four reactions in elongation, and termination. Five these reactions are performed in the beta subunit and two reactions are performed in the alpha subunit.
The 3D protein structure of the enzyme can be found here:PDB. The crystal structure of yeast fatty acid synthase has also been derived, showing both alpha and beta subunits.
Mechanism.
Activation.
The activation of yeast FAS occurs in the alpha subunit. The reaction is performed by the holo-(acyl-carrier-protein) synthase (ACPS) domain. ACPS attaches the 4′-phosphopantetheine prosthetic group of CoA to the acyl carrier protein (ACP) domain, which is found in the N terminus of the α subunit. ACP is the only “mobile” domain of the enzyme complex, in which it moves intermediate substrates along all of the catalytic centers the enzyme, most notably the alpha and beta subunits.
Priming.
The next step is priming, or the initiation of fatty acid synthesis. Priming is performed in the β subunit, and is catalyzed by the acetyltransferase (AT, equivalent to bacterial (acyl-carrier-protein) S-acetyltransferase) domain, which initiates the process of fatty acid synthesis. Here, acetyltransferase transfers the acetate group from acetyl-CoA onto the SH group of the 4′-phosphopantetheine prosthetic group of ACP, which had been attached during activation.
Elongation.
Elongation involves four main reactions:
Elongation itself occurs in mainly in the α subunit, though the entire process required for elongation is a coordinated system which involves the α and β subunits. ACP first delivers the acetate group, which had been attached during priming, to the ketoacyl synthase (KS) domain in the α subunit. ACP then moves back to the β subunit to the malonyl/palmitoyl-transacylase (MPT, equivalent to bacterial malonyl transacylase) domain and binds to a malonyl of malonyl-CoA, which will be used for elongation. The newly bound malonyl-ACP then swings back to the KS domain and transfers the malonate group for chain elongation. Now in the KS domain, the bound acyl group is condensed with the malonate to form 3-ketoacyl intermediate: β-ketobutyryl-ACP, releasing carbon dioxide in the process.
In the α subunit is also the ketoacyl reductase (KR) domain. The KR domain is NADPH dependent, and catalyzes substrate reduction, in which ketobutyryl-ACP is reduced to β-hydroxyacyl-ACP by NADPH.
The β-hydroxyacyl-ACP is then transferred back to the β subunit, where it is dehydrated in 3-Hydroxyacyl ACP dehydrase (DH) domain. Another reduction reaction then performed in the enoyl reductase (ER) domain of the β subunit to form a saturated acyl-ACP chain. Finally, ACP brings the substrate back to the KS domain of the α subunit for another cycle of elongation. The elongation cycle is often repeated 3 more times before termination.
Notice the unique characteristic of ACP, which is vital to fatty acid synthesis in its role of shuttling the reaction intermediates between the α and β subunits’ catalytic domains.
Termination.
Once the fatty acid chain reaches 16 or 18 carbons long after cycles of elongation, termination occurs. In the final round of elongation, rather than being taken back to the KS domain, the fatty acid product, which is still bound to ACP, is taken from the ER domain to the MPT domain. Here, CoA is attached to the fatty acid, and the resulting long chain fatty acyl-CoA is released into the cytosol.
Applications.
Fatty acids are key components of a cell, therefore, the regulation or inhibition of fatty acid synthesis hold severe consequences for cellular function. The malfunction of the fatty acid synthesis pathway can result in cancer and obesity. However, the significance of fatty acid synthesis also make the fatty acid synthesis pathway a potential target for the search and study of anticancer and antibiotic drugs. It has been found that in humans, fatty acid synthase, is overly expressed in cancer cells. Therefore, FAS, which has been associated only with energy production prior, is now associated with aggressive tumor growth and survival. Studies have also found that human fatty acid synthase is overly expressed in prostate cancer cells.
References.
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Further reading.
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https://en.wikipedia.org/wiki?curid=14542228
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14542251
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Flavonol-3-O-beta-glucoside O-malonyltransferase
|
Class of enzymes
In enzymology, a flavonol-3-O-beta-glucoside O-malonyltransferase (EC 2.3.1.116) is an enzyme that catalyzes the chemical reaction
malonyl-CoA + flavonol 3-O-beta-D-glucoside formula_0 CoA + flavonol 3-O-(6-O-malonyl-beta-D-glucoside)
Thus, the two substrates of this enzyme are malonyl-CoA and flavonol 3-O-beta-D-glucoside, whereas its two products are CoA and flavonol 3-O-(6-O-malonyl-beta-D-glucoside).
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is malonyl-CoA:flavonol-3-O-beta-D-glucoside 6"-O-malonyltransferase. Other names in common use include flavonol 3-O-glucoside malonyltransferase, MAT-3, and malonyl-coenzyme A:flavonol-3-O-glucoside malonyltransferase.
References.
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14542262
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Flavonol-3-O-triglucoside O-coumaroyltransferase
|
In enzymology, a flavonol-3-O-triglucoside O-coumaroyltransferase (EC 2.3.1.173) is an enzyme that catalyzes the chemical reaction
4-coumaroyl-CoA + a flavonol 3-O-[beta-D-glucosyl-(1->2)-beta-D-glucosyl-(1->2)-beta-D-glucoside] formula_0 CoA + a flavonol 3-O-[6-(4-coumaroyl)-beta-D-glucosyl-(1->2)-beta-D-glucosyl-(1->2)- beta-D-glucoside]
The 3 substrates of this enzyme are 4-coumaroyl-CoA, flavonol, and 3-O-beta-D-glucosyl-(1->2)-beta-D-glucosyl-(1->2)-beta-D-glucoside, whereas its 4 products are CoA, flavonol, 3-O-[6-(4-coumaroyl)-beta-D-glucosyl-(1->2)-beta-D-glucosyl-(1->2)-, and beta-D-glucoside].
This enzyme belongs to the family of transferases, to be specific those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is 4-coumaroyl-CoA:flavonol-3-O-[beta-D-glucosyl-(1->2)-beta-D-glucosid e] 6-O-4-coumaroyltransferase.
References.
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14542297
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Formylmethanofuran—tetrahydromethanopterin N-formyltransferase
|
In enzymology, a formylmethanofuran-tetrahydromethanopterin N-formyltransferase (EC 2.3.1.101) is an enzyme that catalyzes the chemical reaction
formylmethanofuran + 5,6,7,8-tetrahydromethanopterin formula_0 methanofuran + 5-formyl-5,6,7,8-tetrahydromethanopterin
Thus, the two substrates of this enzyme are formylmethanofuran and 5,6,7,8-tetrahydromethanopterin, whereas its two products are methanofuran and 5-formyl-5,6,7,8-tetrahydromethanopterin.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is formylmethanofuran:5,6,7,8-tetrahydromethanopterin 5-formyltransferase. Other names in common use include formylmethanofuran-tetrahydromethanopterin formyltransferase, formylmethanofuran:tetrahydromethanopterin formyltransferase, N-formylmethanofuran(CHO-MFR):tetrahydromethanopterin(H4MPT), formyltransferase, FTR, formylmethanofuran:5,6,7,8-tetrahydromethanopterin, and N5-formyltransferase. This enzyme participates in folate biosynthesis.
Ftr from the thermophilic methanogen "Methanopyrus kandleri" (which has an optimum growth temperature 98 degrees C) is a hyperthermophilic enzyme that is absolutely dependent on the presence of lyotropic salts for activity and thermostability. The crystal structure of Ftr, determined to a reveals a homotetramer composed essentially of two dimers. Each subunit is subdivided into two tightly associated lobes both consisting of a predominantly antiparallel beta sheet flanked by alpha helices forming an alpha/beta sandwich structure. The approximate location of the active site was detected in a region close to the dimer interface. Ftr from the mesophilic methanogen "Methanosarcina barkeri" and the sulphate-reducing archaeon "Archaeoglobus fulgidus" have a similar structure.
In the methylotrophic bacterium "Methylobacterium extorquens", Ftr interacts with three other polypeptides to form an Ftr/hydrolase complex which catalyses the hydrolysis of formyl-tetrahydromethanopterin to formate during growth on C1 substrates.
Structural studies.
As of late 2007, 5 structures have been solved for this class of enzymes, with PDB accession codes 1FTR, 1M5H, 1M5S, 2FHJ, and 2FHK.
References.
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https://en.wikipedia.org/wiki?curid=14542297
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14542313
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Galactarate O-hydroxycinnamoyltransferase
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In enzymology, a galactarate O-hydroxycinnamoyltransferase (EC 2.3.1.130) is an enzyme that catalyzes the chemical reaction
feruloyl-CoA + galactarate formula_0 CoA + O-feruloylgalactarate
Thus, the two substrates of this enzyme are feruloyl-CoA and galactarate, whereas its two products are CoA and O-feruloylgalactarate.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is feruloyl-CoA:galactarate O-(hydroxycinnamoyl)transferase. This enzyme is also called galacturate hydroxycinnamoyltransferase.
References.
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https://en.wikipedia.org/wiki?curid=14542313
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14542323
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Galactolipid O-acyltransferase
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In enzymology, a galactolipid O-acyltransferase (EC 2.3.1.134) is an enzyme that catalyzes the chemical reaction
2 mono-beta-D-galactosyldiacylglycerol formula_0 acylmono-beta-D-galactosyldiacylglycerol + mono-beta-D-galactosylacylglycerol
Hence, this enzyme has one substrate, mono-beta-D-galactosyldiacylglycerol, and two products, acylmono-beta-D-galactosyldiacylglycerol and mono-beta-D-galactosylacylglycerol.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is mono-beta-D-galactosyldiacylglycerol:mono-beta-D-galactosyldiacylgly cerol acyltransferase. This enzyme is also called galactolipid:galactolipid acyltransferase. This enzyme participates in glycerolipid metabolism.
References.
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14542338
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Galactosylacylglycerol O-acyltransferase
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In enzymology, a galactosylacylglycerol O-acyltransferase (EC 2.3.1.141) is an enzyme that catalyzes the chemical reaction
acyl-[acyl-carrier-protein] + sn-3-D-galactosyl-sn-2-acylglycerol formula_0 [acyl-carrier-protein] + D-galactosyldiacylglycerol
Thus, the two substrates of this enzyme are acyl-[acyl-carrier-protein] and sn-3-D-galactosyl-sn-2-acylglycerol, whereas its two products are acyl-carrier-protein and D-galactosyldiacylglycerol.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acyl-[acyl-carrier-protein]:D-galactosylacylglycerol O-acyltransferase. Other names in common use include acyl-acyl-carrier protein: lysomonogalactosyldiacylglycerol, acyltransferase, and acyl-ACP:lyso-MGDG acyltransferase. This enzyme participates in glycerolipid metabolism.
References.
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https://en.wikipedia.org/wiki?curid=14542338
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14542352
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Gamma-glutamylcyclotransferase
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Class of enzymes
In enzymology, a gamma-glutamylcyclotransferase (EC 2.3.2.4) is an enzyme that catalyzes the chemical reaction
(5-L-glutamyl)-L-amino acid formula_0 5-oxoproline + L-amino acid
Hence, this enzyme has one substrate, (5-L-glutamyl)-L-amino acid, and two products, 5-oxoproline and L-amino acid.
This enzyme belongs to the family of transferases, specifically the aminoacyltransferases. The systematic name of this enzyme class is (5-L-glutamyl)-L-amino-acid 5-glutamyltransferase (cyclizing). Other names in common use include gamma-glutamyl-amino acid cyclotransferase, gamma-L-glutamylcyclotransferase, and L-glutamic cyclase. This enzyme participates in glutathione metabolism.
Structural studies.
As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes 2PN7 and 2RBH.
References.
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https://en.wikipedia.org/wiki?curid=14542352
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14542381
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Gentamicin 2'-N-acetyltransferase
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In enzymology, a gentamicin 2'-N-acetyltransferase (EC 2.3.1.59) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + gentamicin C1a formula_0 CoA + N2'-acetylgentamicin C1a
Thus, the two substrates of this enzyme are acetyl-CoA and gentamicin C1a, whereas its two products are CoA and N2'-acetyl gentamicin C1a.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:gentamicin-C1a N2'-acetyltransferase. Other names in common use include gentamicin acetyltransferase II, gentamicin 2'-N-acetyltransferase, and acetyl-CoA:gentamicin-C1a N2'-acetyltransferase.
References.
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https://en.wikipedia.org/wiki?curid=14542381
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14542396
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Gentamicin 3'-N-acetyltransferase
|
In enzymology, a gentamicin 3'-N-acetyltransferase (EC 2.3.1.60) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + gentamicin C formula_0 CoA + N3'-acetylgentamicin C
Thus, the two substrates of this enzyme are acetyl-CoA and gentamicin C, whereas its two products are CoA and N3'-acetylgentamicin C.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:gentamicin-C N3'-acetyltransferase. Other names in common use include gentamicin acetyltransferase I, aminoglycoside acetyltransferase AAC(3)-1, gentamicin 3'-N-acetyltransferase, and acetyl-CoA:gentamicin-C N3'-acetyltransferase.
References.
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https://en.wikipedia.org/wiki?curid=14542396
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14542407
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Glucarate O-hydroxycinnamoyltransferase
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In enzymology, a glucarate O-hydroxycinnamoyltransferase (EC 2.3.1.131) is an enzyme that catalyzes the chemical reaction
sinapoyl-CoA + glucarate formula_0 CoA + O-sinapoylglucarate
Thus, the two substrates of this enzyme are sinapoyl-CoA and glucarate, whereas its two products are CoA and O-sinapoylglucarate.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is sinapoyl-CoA:glucarate O-(hydroxycinnamoyl)transferase.
References.
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https://en.wikipedia.org/wiki?curid=14542407
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14542418
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Glucarolactone O-hydroxycinnamoyltransferase
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In enzymology, a glucarolactone O-hydroxycinnamoyltransferase (EC 2.3.1.132) is an enzyme that catalyzes the chemical reaction
sinapoyl-CoA + glucarolactone formula_0 CoA + O-sinapoylglucarolactone
Thus, the two substrates of this enzyme are sinapoyl-CoA and glucarolactone, whereas its two products are CoA and O-sinapoylglucarolactone.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is sinapoyl-CoA:glucarolactone O-(hydroxycinnamoyl)transferase.
References.
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https://en.wikipedia.org/wiki?curid=14542418
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14542431
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Glucosamine-1-phosphate N-acetyltransferase
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In enzymology, a glucosamine-1-phosphate N-acetyltransferase (EC 2.3.1.157) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + alpha-D-glucosamine 1-phosphate formula_0 CoA + N-acetyl-alpha-D-glucosamine 1-phosphate
Thus, the two substrates of this enzyme are acetyl-CoA and alpha-D-glucosamine 1-phosphate, whereas its two products are CoA and N-acetyl-alpha-D-glucosamine 1-phosphate.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:alpha-D-glucosamine-1-phosphate N-acetyltransferase. This enzyme participates in aminosugars metabolism.
Structural studies.
As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes 2OI5, 2OI6, and 2OI7.
References.
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[
{
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"text": "\\rightleftharpoons"
}
] |
https://en.wikipedia.org/wiki?curid=14542431
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14542441
|
Glucosamine N-acetyltransferase
|
In enzymology, a glucosamine N-acetyltransferase (EC 2.3.1.3) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + D-glucosamine formula_0 CoA + N-acetyl-D-glucosamine
Thus, the two substrates of this enzyme are acetyl-CoA and D-glucosamine, whereas its two products are CoA and N-acetyl-D-glucosamine.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:D-glucosamine N-acetyltransferase. Other names in common use include glucosamine acetylase, and glucosamine acetyltransferase. This enzyme participates in aminosugars metabolism.
References.
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
}
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https://en.wikipedia.org/wiki?curid=14542441
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14542468
|
Glutamate N-acetyltransferase
|
Enzyme
In enzymology, a glutamate "N"-acetyltransferase (EC 2.3.1.35) is an enzyme that catalyzes the chemical reaction
N2-acetyl-L-ornithine + L-glutamate formula_0 L-ornithine + N-acetyl-L-glutamate
Thus, the two substrates of this enzyme are N2-acetyl-L-ornithine and L-glutamate, whereas its two products are L-ornithine and N-acetyl-L-glutamate.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is N2-acetyl-L-ornithine:L-glutamate N-acetyltransferase. This enzyme participates in the urea cycle and metabolism of amino groups.
Structural studies.
As of late 2007, 4 structures have been solved for this class of enzymes, with PDB accession codes 1VRA, 1VZ6, 1VZ7, and 1VZ8.
References.
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
}
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https://en.wikipedia.org/wiki?curid=14542468
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14542487
|
Glutamine N-acyltransferase
|
In enzymology, a glutamine N-acyltransferase (EC 2.3.1.68) is an enzyme that catalyzes the chemical reaction
acyl-CoA + L-glutamine formula_0 CoA + N-acyl-L-glutamine
Thus, the two substrates of this enzyme are acyl-CoA and L-glutamine, whereas its two products are CoA and N-acyl-L-glutamine.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acyl-CoA:L-glutamine N-acyltransferase.
References.
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
}
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https://en.wikipedia.org/wiki?curid=14542487
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14542503
|
Glutamine N-phenylacetyltransferase
|
Enzyme
In enzymology, a glutamine N-phenylacetyltransferase (EC 2.3.1.14) is an enzyme that catalyzes the chemical reaction
phenylacetyl-CoA + L-glutamine formula_0 CoA + alpha-N-phenylacetyl-L-glutamine
Thus, the two substrates of this enzyme are phenylacetyl-CoA and L-glutamine, whereas its two products are CoA and alpha-N-phenylacetyl-L-glutamine.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is phenylacetyl-CoA:L-glutamine alpha-N-phenylacetyltransferase. Other names in common use include glutamine phenylacetyltransferase, and phenylacetyl-CoA:L-glutamine N-acetyltransferase. This enzyme participates in tyrosine metabolism and phenylalanine metabolism.
References.
<templatestyles src="Reflist/styles.css" />
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
}
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https://en.wikipedia.org/wiki?curid=14542503
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14543043
|
Glutaminyl-peptide cyclotransferase
|
In enzymology, a glutaminyl-peptide cyclotransferase (EC 2.3.2.5) is an enzyme that catalyzes the chemical reaction
L-glutaminyl-peptide formula_0 5-oxoprolyl-peptide + NH3 or
L-glutamyl-peptide formula_0 5-oxoprolyl-peptide + H2O
Hence, this enzyme has one substrate, L-glutaminyl-peptide or L-glutamyl-peptide, and two products, 5-oxoprolyl-peptide and NH3 or H2O. The N-terminal 5-oxoproline residue on the peptide is also commonly known as pyroglutamic acid.
This enzyme belongs to the family of transferases, specifically the aminoacyltransferases. The systematic name of this enzyme class is L-glutaminyl-peptide gamma-glutamyltransferase (cyclizing). Other names in common use include glutaminyl-tRNA cyclotransferase, glutaminyl cyclase, and glutaminyl-transfer ribonucleate cyclotransferase.
Structural studies.
As of late 2007, 8 structures have been solved for this class of enzymes, with PDB accession codes 2AFM, 2AFO, 2AFS, 2AFU, 2AFW, 2AFX, 2AFZ, and 2IWA.
Human gene.
QPCT - note that Q is one-letter abbreviation for glutamine, and glutaminyl is the name of the acyl group.
References.
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[
{
"math_id": 0,
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https://en.wikipedia.org/wiki?curid=14543043
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14543057
|
Glutathione gamma-glutamylcysteinyltransferase
|
In enzymology, a glutathione gamma-glutamylcysteinyltransferase (EC 2.3.2.15) is an enzyme that catalyzes the chemical reaction
glutathione + [Glu(-Cys)]n-Gly formula_0 Gly + [Glu(-Cys)]n+1-Gly
Thus, the two substrates of this enzyme are glutathione and [Glu(-Cys)]n-Gly, whereas its two products are Gly and [Glu(-Cys)]n+1-Gly.
This enzyme belongs to the family of transferases, specifically the aminoacyltransferases. The systematic name of this enzyme class is glutathione:poly(4-glutamyl-cysteinyl)glycine 4-glutamylcysteinyltransferase. Other names in common use include phytochelatin synthase, and gamma-glutamylcysteine dipeptidyl transpeptidase.
Structural studies.
As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes 2BTW and 2BU3.
References.
<templatestyles src="Reflist/styles.css" />
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14543057
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14543077
|
Glycerol-3-phosphate O-acyltransferase
|
In enzymology, a glycerol-3-phosphate O-acyltransferase (EC 2.3.1.15) is an enzyme that catalyzes the chemical reaction
acyl-CoA + sn-glycerol 3-phosphate formula_0 CoA + 1-acyl-sn-glycerol 3-phosphate
Thus, the two substrates of this enzyme are acyl-CoA and sn-glycerol 3-phosphate, whereas its two products are CoA and 1-acyl-sn-glycerol 3-phosphate.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acyl-CoA:sn-glycerol-3-phosphate 1-O-acyltransferase. Other names in common use include alpha-glycerophosphate acyltransferase, 3-glycerophosphate acyltransferase, ACP:sn-glycerol-3-phosphate acyltransferase, glycerol 3-phosphate acyltransferase, glycerol phosphate acyltransferase, glycerol phosphate transacylase, glycerophosphate acyltransferase, glycerophosphate transacylase, sn-glycerol 3-phosphate acyltransferase, and sn-glycerol-3-phosphate acyltransferase. This enzyme participates in glycerolipid metabolism and glycerophospholipid metabolism. The later pathways in human is part of the WikiPathways machine readable pathway collection.
Structural studies.
As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes 1IUQ and 1K30. Currently 4 different proteins are assigned to this reaction, GPAT1, GPAT2, GPAT3 and GPAT4. GPAT1 and 2 are considered mitochondrial proteins.
References.
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
}
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https://en.wikipedia.org/wiki?curid=14543077
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14543094
|
Glycerophospholipid acyltransferase (CoA-dependent)
|
In enzymology, a glycerophospholipid acyltransferase (CoA-dependent) (EC 2.3.1.148) is an enzyme that catalyzes the chemical reaction
1-organyl-2-acyl-sn-glycero-3-phosphocholine + 1-organyl-2-lyso-sn-glycero-3-phosphoethanolamine formula_0 1-organyl-2-acyl-sn-glycero-3-phosphoethanolamine + 1-organyl-2-lyso-sn-glycero-3-phosphocholine
Thus, the two substrates of this enzyme are 1-organyl-2-acyl-sn-glycero-3-phosphocholine and 1-organyl-2-lyso-sn-glycero-3-phosphoethanolamine, whereas its two products are 1-organyl-2-acyl-sn-glycero-3-phosphoethanolamine and 1-organyl-2-lyso-sn-glycero-3-phosphocholine.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is 1-organyl-2-acyl-sn-glycero-3-phosphocholine:1-organyl-2-lyso-sn-gly cero-3-phosphoethanolamine acyltransferase (CoA-dependent).
References.
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14543094
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14543109
|
Glycerophospholipid arachidonoyl-transferase (CoA-independent)
|
In the field of enzymology, a glycerophospholipid arachidonoyl-transferase (CoA-independent) (EC 2.3.1.147) is an enzyme that catalyzes the chemical reaction:
1-organyl-2-arachidonoyl-sn-glycero-3-phosphocholine + 1-organyl-2-lyso-sn-glycero-3-phosphoethanolamine formula_0 1-organyl-2-arachidonoyl-sn-glycero-3-phosphoethanolamine + 1-organyl-2-lyso-sn-glycero-3-phosphocholine
This enzyme catalyzes the transfer of arachidonic acid and other polyenoic fatty acids from intact choline or ethanolamine-containing glycerophospholipids to the sn-2 position of a lyso- glycerophospholipid. The organyl group on sn-1 of the donor or acceptor molecule can be alkyl, acyl or alk-1-enyl. This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups.
Nomenclature.
The systematic name of this enzyme class is 1-organyl-2-arachidonoyl-sn-glycero-3-phosphocholine:1-organyl-2-lys o-sn-glycero-3-phosphoethanolamine arachidonoyltransferase (CoA-independent).
References.
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14543109
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14543131
|
Glycine C-acetyltransferase
|
In enzymology, a glycine C-acetyltransferase (EC 2.3.1.29) is an enzyme that catalyzes the chemical reaction:
acetyl-CoA + glycine formula_0 CoA + 2-amino-3-oxobutanoate
Thus, the two substrates of this enzyme are acetyl-CoA and glycine, whereas its two products are CoA and 2-amino-3-oxobutanoate.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:glycine C-acetyltransferase. Other names in common use include 2-amino-3-ketobutyrate CoA ligase, 2-amino-3-ketobutyrate coenzyme A ligase, 2-amino-3-ketobutyrate-CoA ligase, glycine acetyltransferase, and aminoacetone synthase. This enzyme participates in glycine, serine and threonine metabolism. It employs one cofactor, pyridoxal phosphate.
Structural studies.
As of late 2007, only one structure has been solved for this class of enzymes, with the PDB accession code 1FC4.
References.
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14543131
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14543145
|
Glycine N-acyltransferase
|
Enzyme
In enzymology, a glycine N-acyltransferase (GLYAT), also known as acyl-CoA:glycine N-acyltransferase (ACGNAT), (EC 2.3.1.13) is an enzyme that catalyzes the chemical reaction
acyl-CoA + glycine formula_0 CoA + N-acylglycine
Thus, the two substrates of this enzyme are acyl-CoA and glycine, whereas its two products are CoA and N-acylglycine. This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acyl-CoA:glycine N-acyltransferase. Other names in common use include glycine acyltransferase, and glycine-N-acylase.
This enzyme plays a prominent role in converting benzoic acid (benzoate) into hippuric acid (N-benzoylglycine). Benzoic acid is metabolized by butyrate-CoA ligase into an intermediate product, benzoyl-CoA, which is then metabolized by glycine N-acyltransferase into hippuric acid.
References.
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[
{
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https://en.wikipedia.org/wiki?curid=14543145
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14543165
|
Glycine N-benzoyltransferase
|
In enzymology, a glycine N-benzoyltransferase (EC 2.3.1.71) is an enzyme that catalyzes the chemical reaction
benzoyl-CoA + glycine formula_0 CoA + N-benzoylglycine
Thus, the two substrates of this enzyme are benzoyl-CoA and glycine, whereas its two products are CoA and N-benzoylglycine.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is benzoyl-CoA:glycine N-benzoyltransferase. Other names in common use include benzoyl CoA-amino acid N-acyltransferase, and benzoyl-CoA:glycine N-acyltransferase. This enzyme participates in phenylalanine metabolism.
References.
<templatestyles src="Reflist/styles.css" />
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
}
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https://en.wikipedia.org/wiki?curid=14543165
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14543179
|
Glycoprotein N-palmitoyltransferase
|
In enzymology, a glycoprotein N-palmitoyltransferase (EC 2.3.1.96) is an enzyme that catalyzes the chemical reaction
palmitoyl-CoA + glycoprotein formula_0 CoA + N-palmitoylglycoprotein
Thus, the two substrates of this enzyme are palmitoyl-CoA and glycoprotein, whereas its two products are CoA and N-palmitoylglycoprotein.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is palmitoyl-CoA:glycoprotein N-palmitoyltransferase. This enzyme is also called mucus glycoprotein fatty acyltransferase. This enzyme participates in aminosugars metabolism. This enzyme has at least one effector, Dithiothreitol.
References.
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14543179
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14543193
|
Glycoprotein O-fatty-acyltransferase
|
In enzymology, a glycoprotein O-fatty-acyltransferase (EC 2.3.1.142) is an enzyme that catalyzes the chemical reaction
palmitoyl-CoA + mucus glycoprotein formula_0 CoA + O-palmitoylglycoprotein
Thus, the two substrates of this enzyme are palmitoyl-CoA and mucus glycoprotein, whereas its two products are CoA and O-palmitoylglycoprotein.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is fatty-acyl-CoA:mucus-glycoprotein fatty-acyltransferase. This enzyme is also called protein acyltransferase.
References.
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[
{
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"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14543193
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14543210
|
Glycylpeptide N-tetradecanoyltransferase
|
In enzymology, a glycylpeptide N-tetradecanoyltransferase (EC 2.3.1.97) is an enzyme that catalyzes the chemical reaction
tetradecanoyl-CoA + glycylpeptide formula_0 CoA + N-tetradecanoylglycylpeptide
Thus, the two substrates of this enzyme are tetradecanoyl-CoA and glycylpeptide, whereas its two products are CoA and N-tetradecanoylglycylpeptide. It participates in the N-Myristoylation of proteins, and in vertebrates there are two isoenzymes NMT1 and NMT2.
Besides tetradecanoyl-CoA, this enzyme is also capable of using modified versions of this substrate. In human retina, an even wider range of fatty acids, including 14:1 n–9, 14:2n–6, and 12:0, are accepted by the enzyme and grafted onto guanylate cyclase activators. This is mainly a result of a special set of fatty-acid-CoA substrates available in the retina.
Nomenclature.
This enzyme belongs to the family of transferases, specifically those N-acyltransferases transferring groups other than aminoacyl groups (cd04301). The systematic name of this enzyme class is tetradecanoyl-CoA:glycylpeptide N-tetradecanoyltransferase. Other names in common use include peptide N-myristoyltransferase (NMT), myristoyl-CoA-protein N-myristoyltransferase, myristoyl-coenzyme A:protein N-myristoyl transferase, myristoylating enzymes, and protein N-myristoyltransferase.
Structural studies.
As of late 2007, 9 structures have been solved for this class of enzymes, with PDB accession codes 1IIC, 1IID, 1IYK, 1IYL, 1RXT, 2NMT, 2P6E, 2P6F, and 2P6G.
The enzyme folds into two domains, each with a double EF-hand arrangement.
References.
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[
{
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"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14543210
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14543261
|
Histidine N-acetyltransferase
|
In enzymology, a histidine N-acetyltransferase (EC 2.3.1.33) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + L-histidine formula_0 CoA + N-acetyl-L-histidine
Thus, the two substrates of this enzyme are acetyl-CoA and L-histidine, whereas its two products are CoA and N-acetyl-L-histidine.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:L-histidine N-acetyltransferase. Other names in common use include acetylhistidine synthetase, and histidine acetyltransferase.
References.
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14543261
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14543287
|
Homocitrate synthase
|
Enzyme
In enzymology, a homocitrate synthase (EC 2.3.3.14) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + H2O + 2-oxoglutarate formula_0 (R)-2-hydroxybutane-1,2,4-tricarboxylate + CoA
The 3 substrates of this enzyme are acetyl-CoA, H2O, and 2-oxoglutarate, whereas its two products are (R)-2-hydroxybutane-1,2,4-tricarboxylate and CoA.
This enzyme belongs to the family of transferases, specifically those acyltransferases that convert acyl groups into alkyl groups on transfer. The systematic name of this enzyme class is acetyl-CoA:2-oxoglutarate C-acetyltransferase (thioester-hydrolysing, carboxymethyl forming). Other names in common use include 2-hydroxybutane-1,2,4-tricarboxylate 2-oxoglutarate-lyase, (CoA-acetylating), acetyl-coenzyme A:2-ketoglutarate C-acetyl transferase, and homocitrate synthetase. This enzyme participates in lysine biosynthesis and pyruvate metabolism.
References.
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https://en.wikipedia.org/wiki?curid=14543287
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14543303
|
Homoserine O-acetyltransferase
|
Enzyme
In enzymology, a homoserine O-acetyltransferase (EC 2.3.1.31) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + L-homoserine formula_0 CoA + O-acetyl-L-homoserine
Thus, the two substrates of this enzyme are acetyl-CoA and L-homoserine, whereas its two products are CoA and O-acetyl-L-homoserine.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:L-homoserine O-acetyltransferase. Other names in common use include homoserine acetyltransferase, homoserine transacetylase, homoserine-O-transacetylase, and L-homoserine O-acetyltransferase. This enzyme participates in methionine metabolism and sulfur metabolism.
Structural studies.
As of late 2007, only one structure has been solved for this class of enzymes, with the PDB accession code 2B61.
References.
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14543303
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14543317
|
Homoserine O-succinyltransferase
|
Enzyme
In enzymology, a homoserine O-succinyltransferase (EC 2.3.1.46) is an enzyme that catalyzes the chemical reaction
succinyl-CoA + L-homoserine formula_0 CoA + O-succinyl-L-homoserine
Thus, the two substrates of this enzyme are succinyl-CoA and L-homoserine, whereas its two products are CoA and O-succinyl-L-homoserine.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is succinyl-CoA:L-homoserine O-succinyltransferase. Other names in common use include homoserine O-transsuccinylase, and homoserine succinyltransferase. This enzyme participates in methionine metabolism and sulfur metabolism.
Structural studies.
As of late 2016, three structures have been solved for this class of enzymes, with PDB accession codes 2GHR, 2H2W, and 2VDJ.
References.
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[
{
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https://en.wikipedia.org/wiki?curid=14543317
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14543335
|
Hydrogen-sulfide S-acetyltransferase
|
In enzymology, a hydrogen-sulfide S-acetyltransferase (EC 2.3.1.10) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + hydrogen sulfide formula_0 CoA + thioacetate
Thus, the two substrates of this enzyme are acetyl-CoA and hydrogen sulfide, whereas its two products are CoA and thioacetate.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:hydrogen-sulfide S-acetyltransferase. This enzyme is also called hydrogen-sulfide acetyltransferase.
References.
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{
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https://en.wikipedia.org/wiki?curid=14543335
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14543350
|
Hydroxymethylglutaryl-CoA synthase
|
Class of enzymes
In biochemistry, hydroxymethylglutaryl-CoA synthase or HMG-CoA synthase EC 2.3.3.10 is an enzyme which catalyzes the reaction in which acetyl-CoA condenses with acetoacetyl-CoA to form 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA). This reaction comprises the second step in the mevalonate-dependent isoprenoid biosynthesis pathway. HMG-CoA is an intermediate in both cholesterol synthesis and ketogenesis. This reaction is overactivated in patients with diabetes mellitus type 1 if left untreated, due to prolonged insulin deficiency and the exhaustion of substrates for gluconeogenesis and the TCA cycle, notably oxaloacetate. This results in shunting of excess acetyl-CoA into the ketone synthesis pathway via HMG-CoA, leading to the development of diabetic ketoacidosis.
<br>
acetyl-CoA + H2O + acetoacetyl-CoA formula_0 ("S")-3-hydroxy-3-methylglutaryl-CoA + CoA
The 3 substrates of this enzyme are acetyl-CoA, H2O, and acetoacetyl-CoA, whereas its two products are ("S")-3-hydroxy-3-methylglutaryl-CoA and CoA.
In humans, the protein is encoded by the "HMGCS1" gene on chromosome 5.
Classification.
This enzyme belongs to the family of transferases, specifically those acyltransferases that convert acyl groups into alkyl groups on transfer.
Nomenclature.
The systematic name of this enzyme class is acetyl-CoA:acetoacetyl-CoA C-acetyltransferase (thioester-hydrolysing, carboxymethyl-forming). Other names in common use include "("S")-3-hydroxy-3-methylglutaryl-CoA acetoacetyl-CoA-lyase", "(CoA-acetylating)", "3-hydroxy-3-methylglutaryl CoA synthetase", "3-hydroxy-3-methylglutaryl coenzyme A synthase", "3-hydroxy-3-methylglutaryl coenzyme A synthetase", "3-hydroxy-3-methylglutaryl-CoA synthase", "3-hydroxy-3-methylglutaryl-coenzyme A synthase", "beta-hydroxy-beta-methylglutaryl-CoA synthase", "HMG-CoA synthase", "acetoacetyl coenzyme A transacetase", "hydroxymethylglutaryl coenzyme A synthase", and "hydroxymethylglutaryl coenzyme A-condensing enzyme".
Mechanism.
HMG-CoA synthase contains an important catalytic cysteine residue that acts as a nucleophile in the first step of the reaction: the acetylation of the enzyme by acetyl-CoA (its first substrate) to produce an acetyl-enzyme thioester, releasing the reduced coenzyme A. The subsequent nucleophilic attack on acetoacetyl-CoA (its second substrate) leads to the formation of HMG-CoA.
Biological role.
This enzyme participates in 3 metabolic pathways: synthesis and degradation of ketone bodies, valine, leucine and isoleucine degradation, and butanoate metabolism.
Species distribution.
HMG-CoA synthase occurs in eukaryotes, archaea, and certain bacteria.
Eukaryotes.
In vertebrates, there are two different isozymes of the enzyme (cytosolic and mitochondrial); in humans the cytosolic form has only 60.6% amino acid identity with the mitochondrial form of the enzyme. HMG-CoA is also found in other eukaryotes such as insects, plants, and fungi.
Cytosolic.
The cytosolic form is the starting point of the mevalonate pathway, which leads to cholesterol and other sterolic and isoprenoid compounds.
Mitochondrial.
The mitochondrial form is responsible for the biosynthesis of ketone bodies. The gene for the mitochondrial form of the enzyme has three sterol regulatory elements in the 5' flanking region. These elements are responsible for decreased transcription of the message responsible for enzyme synthesis when dietary cholesterol is high in animals: the same is observed for 3-hydroxy-3-methylglutaryl-CoA and the low density lipoprotein receptor.
Bacteria.
In bacteria, isoprenoid precursors are generally synthesised via an alternative, non-mevalonate pathway, however a number of Gram-positive pathogens utilise a mevalonate pathway involving HMG-CoA synthase that is parallel to that found in eukaryotes.
Structural studies.
As of late 2007, 4 structures have been solved for this class of enzymes, with PDB accession codes 1XPK, 1XPL, 1XPM, and 2P8U.
References.
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{
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https://en.wikipedia.org/wiki?curid=14543350
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14543375
|
Icosanoyl-CoA synthase
|
In enzymology, an icosanoyl-CoA synthase (EC 2.3.1.119) is an enzyme that catalyzes the chemical reaction
stearoyl-CoA + malonyl-CoA + 2 NAD(P)H + 2 H+ formula_0 icosanoyl-CoA + CO2 + CoA + 2 NAD(P)+ + H2O
The 5 substrates of this enzyme are stearoyl-CoA, malonyl-CoA, NADH, NADPH, and H+, whereas its 6 products are icosanoyl-CoA, CO2, CoA, NAD+, NADP+, and H2O.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is stearoyl-CoA:malonyl-CoA C-acyltransferase (decarboxylating, oxoacyl- and enoyl-reducing). Other names in common use include acyl-CoA elongase, C18-CoA elongase, and stearoyl-CoA elongase.
References.
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{
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14543399
|
Imidazole N-acetyltransferase
|
In enzymology, an imidazole N-acetyltransferase (EC 2.3.1.2) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + imidazole formula_0 CoA + N-acetylimidazole
Thus, the two substrates of this enzyme are acetyl-CoA and imidazole, whereas its two products are CoA and N-acetylimidazole.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:imidazole N-acetyltransferase. Other names in common use include imidazole acetylase, and imidazole acetyltransferase.
References.
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14543415
|
Indoleacetylglucose—inositol O-acyltransferase
|
In enzymology, an indoleacetylglucose-inositol O-acyltransferase (EC 2.3.1.72) is an enzyme that catalyzes the chemical reaction
1-O-(indol-3-yl)acetyl-beta-D-glucose + myo-inositol formula_0 D-glucose + O-(indol-3-yl)acetyl-myo-inositol
Thus, the two substrates of this enzyme are 1-O-(indol-3-yl)acetyl-beta-D-glucose and myo-inositol, whereas its two products are D-glucose and O-(indol-3-yl)acetyl-myo-inositol.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is 1-O-(indol-3-yl)acetyl-beta-D-glucose:myo-inositol (indol-3-yl)acetyltransferase. Other names in common use include indole-3-acetyl-beta-1-D-glucoside:myo-inositol, indoleacetyltransferase, 1-O-(indol-3-ylacetyl)-beta-D-glucose:myo-inositol, and indole-3-ylacetyltransferase.
References.
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14543437
|
Isocitrate O-dihydroxycinnamoyltransferase
|
In enzymology, an isocitrate O-dihydroxycinnamoyltransferase (EC 2.3.1.126) is an enzyme that catalyzes the chemical reaction
caffeoyl-CoA + isocitrate formula_0 CoA + 2-caffeoylisocitrate
Thus, the two substrates of this enzyme are caffeoyl-CoA and isocitrate, whereas its two products are CoA and 2-caffeoylisocitrate.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is caffeoyl-CoA:isocitrate 3-O-(3,4-dihydroxycinnamoyl)transferase.
References.
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14543461
|
Isoflavone-7-O-beta-glucoside 6"-O-malonyltransferase
|
In enzymology, an isoflavone-7-O-beta-glucoside 6"-O-malonyltransferase (EC 2.3.1.115) is an enzyme that catalyzes the chemical reaction
malonyl-CoA + biochanin A 7-O-beta-D-glucoside formula_0 CoA + biochanin A 7-O-(6-O-malonyl-beta-D-glucoside)
Thus, the two substrates of this enzyme are malonyl-CoA and biochanin A 7-O-beta-D-glucoside, whereas its two products are CoA and biochanin A 7-O-(6-O-malonyl-beta-D-glucoside).
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is malonyl-CoA:isoflavone-7-O-beta-D-glucoside 6"-O-malonyltransferase. Other names in common use include flavone/flavonol 7-O-beta-D-glucoside malonyltransferase, flavone (flavonol) 7-O-glycoside malonyltransferase, malonyl-CoA:flavone/flavonol 7-O-glucoside malonyltransferase, MAT-7, malonyl-coenzyme A:isoflavone 7-O-glucoside-6"-malonyltransferase, and malonyl-coenzyme A:flavone/flavonol-7-O-glycoside malonyltransferase. This enzyme participates in flavonoid biosynthesis and isoflavonoid biosynthesis.
References.
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14543484
|
Isopenicillin N N-acyltransferase
|
In enzymology, an isopenicillin N N-acyltransferase (EC 2.3.1.164) is an enzyme that catalyzes the chemical reaction
phenylacetyl-CoA + isopenicillin N + H2O formula_0 CoA + penicillin G + L-2-aminohexanedioate
The 3 substrates of this enzyme are phenylacetyl-CoA, isopenicillin N, and H2O, whereas its 3 products are CoA, penicillin G, and L-2-aminohexanedioate.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acyl-CoA:isopenicillin N N-acyltransferase. Other names in common use include acyl-coenzyme A:isopenicillin N acyltransferase, and isopenicillin N:acyl-CoA: acyltransferase. This enzyme participates in hydrophobic penicillins biosynthesis.
References.
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14543508
|
Leucine N-acetyltransferase
|
In enzymology, a leucine N-acetyltransferase (EC 2.3.1.66) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + L-leucine formula_0 CoA + N-acetyl-L-leucine
Thus, the two substrates of this enzyme are acetyl-CoA and L-leucine, whereas its two products are CoA and N-acetyl-L-leucine.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:L-leucine N-acetyltransferase. This enzyme is also called leucine acetyltransferase.
References.
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{
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14543529
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Leucyltransferase
|
In enzymology, a leucyltransferase (EC 2.3.2.6) is an enzyme that catalyzes the chemical reaction
L-leucyl-tRNA + protein formula_0 tRNA + L-leucyl-protein
Thus, the two substrates of this enzyme are L-leucyl-tRNA and protein, whereas its two products are tRNA and L-leucyl-protein.
This enzyme belongs to the family of transferases, specifically the aminoacyltransferases. The systematic name of this enzyme class is L-leucyl-tRNA:protein leucyltransferase. Other names in common use include leucyl, phenylalanine-tRNA-protein transferase, leucyl-phenylalanine-transfer ribonucleate-protein, aminoacyltransferase, and leucyl-phenylalanine-transfer ribonucleate-protein transferase.
Structural studies.
As of late 2007, three structures have been solved for this class of enzymes, with PDB accession codes 2CXA, 2DPS, and 2DPT.
References.
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14543561
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Lipoyl(octanoyl) transferase
|
In enzymology, a lipoyl(octanoyl) transferase (EC 2.3.1.181) is an enzyme that catalyzes the chemical reaction
octanoyl-[acyl-carrier-protein] + protein formula_0 protein N6-(octanoyl)lysine + acyl carrier protein
Thus, the two substrates of this enzyme are octanoyl-[acyl-carrier-protein] and protein, whereas its two products are protein N6-(octanoyl)lysine and acyl carrier protein.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is octanoyl-[acyl-carrier-protein]:protein N-octanoyltransferase. Other names in common use include LipB, lipoyl (octanoyl)-[acyl-carrier-protein]-protein, N-lipoyltransferase, lipoyl (octanoyl)-acyl carrier protein:protein transferase, lipoate/octanoate transferase, lipoyltransferase, octanoyl-[acyl carrier protein]-protein N-octanoyltransferase, and lipoyl(octanoyl)transferase. This enzyme participates in lipoic acid metabolism.
References.
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14543575
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Long-chain-alcohol O-fatty-acyltransferase
|
In enzymology, a long-chain-alcohol O-fatty-acyltransferase (EC 2.3.1.75) is an enzyme that catalyzes the chemical reaction
acyl-CoA + a long-chain alcohol formula_0 CoA + a long-chain ester
Thus, the two substrates of this enzyme are acyl-CoA and long-chain alcohol, whereas its two products are CoA and long-chain ester.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acyl-CoA:long-chain-alcohol O-acyltransferase. Other names in common use include wax synthase, and wax-ester synthase. In general, wax syntheses naturally accept acyl groups with carbon chain lengths of C16 or C18 and linear alcohols with carbon chain lengths ranging from C12 to C20.
Variation.
There are three unrelated families of wax syntheses found in many organisms including bacteria, higher plants, and animals in two known distinct forms: either just as a wax synthase enzyme, which is found predominantly in eukaryotes, or as an enzyme with dual wax synthase and acyl CoA:diacylglycerol acyltransferase function, which is often the final enzyme in the biosynthetic pathway responsible for wax ester production from fatty alcohols and fatty acyl-CoAs and is found predominantly in prokaryotes.
Prokaryotic bacteria.
Acinetobacter.
There are frequent reports of wax esters biosynthesis in bacteria of the Acinetobacter genus. In particular, it has been shown that the Acinetobacter calcoaceticus ADP1 strain synthesizes wax esters through a bifunctional wax ester synthase/acyl-CoA: diacylglycerol acyltransferase (WS/DGAT) and that this complex can be functionally expressed in different bacterial hosts, suggesting the potential for potential microbial production of cheap jojoba-like wax esters. Furthermore, this was the first instance of bacterial WS/DGAT discovered. Finally, Acinetobacter has been considered as an alternative source for jojoba-like wax ester production, but is limited by the fact that its wax ester content never exceeds 14% of the cell's dry weight.
Rhodococcus jostii RHA1.
Scientists have identified at least 14 genes in the Rhodococcus jostii RHA1 genome that encode putative wax ester synthase/acyl-CoA:diacylglycerol acyltransferase enzymes (WS/DGAT) with lengths ranging from 430 to 497 amino acid residues except for atf121 product, which was composed of 301 amino acid residues.
Other bacteria that have been shown to produce wax esters through homologs for the WS/DGAT gene include "Psychrobacter arcticus 273-4" and "P. Cryohalolentis K5", with only one a single copy of the WS/DGAT gene, "M. aquaeolei VT8", with 4 homologs for WS/DGAT and "A. Baylyi", with a mixture of wax esters even though it only has one WS/DGAT coding gene. "M. tuberculosis" has also been shown to contain 15 atf genes encoding WS/DGATs. Several of these bacterial WS/DGAT enzymes have a broad substrate range despite naturally producing a small range of wax esters.
Plants.
"Arabidopsis thaliana".
Scientists have also identified, characterized, and shown the WSD1 gene in "Arabidopsis thaliana" to encode a bifunctional wax ester synthase/diacylglycerol acyltransferase enzyme that is embedded in the ER membrane, in which the wax synthase portion is critical to wax ester synthesis using long-chain and very-long-chain primary alcohols with C fatty acids.
Jojoba.
Although the first wax synthase in plants was identified in the jojoba plant, the jojoba wax synthase could not be functionally expressed in microorganisms like "E. coli" and "S. cerevisiae".
Animals.
Birds.
The enzyme products of genes AdWS4, TaWS4, GgWS1, GgWS2, GgWS4, and GgDGAT1 sequences have been shown to catalyze wax ester syntheses in several bird species.
Mammals.
Scientists have discovered cDNA encoding wax synthase in the preputial gland of mice. Furthermore, it has been shown that the wax synthase gene is located on the X chromosome, the expression of which lead to the formation of wax monoesters from straight chain, saturated, unsaturated, and polyunsaturated fatty alcohols and acids and that the formation of wax esters in mammals involves a two step biosynthetic pathway involving fatty acyl-CoA reductase and wax synthase enzymes.
Humans.
The enzymes produced by X-linked genes AWAT1 and AWAT2 have been shown to esterify long chain alcohols to produce wax esters and is most predominantly expressed in skin. Both enzymes have dissimilar substrate specificities: AWAT1 prefers decyl alcohol (C10) and AWAT2 prefers C16 and C18 alcohols while using oleoyl-CoA as the acyl donor. However, when using acetyl alcohol as the acyl acceptor, AWAT1 prefers saturated acyl groups, while AWAT2 shows activity with all four acyl-CoAs and performs two times better with unsaturated acyl-CoAs than with saturated ones. Along with the murine wax ester synthase, AWAT1 and AWAT2 are likely the most significant contributors in wax ester production in mammals.
Enzyme structure.
While the function of the molecule has been studied, its structure has yet to be identified.
Industrial relevance.
There is a large demand for large-scale production of cheap jojoba-like wax esters since they have multiple commercial uses. Scientists have found a way to achieve substantial biosynthesis and accumulation of neutral lipids in "E. coli", allowing for the possibilities of economic biotechnological production of cheap jojoba oil equivalents, the use of which was previously limited by its high price resulting in its restriction to medical and cosmetic applications.
In addition, the knowledge gathered so far on the substrate specificity of different forms of wax synthase allows for scientists to explore the use of yeast cells, in particular "Saccharomyces cerevisiae", in the production of biodiesel fuels. "S. Cerevisiae" is a well-documented industrial microorganism and is easy to cultivate, manipulate genetically, quick growth, and fatty acid metabolism, making it an ideal candidate for the expression of wax esters. "S. Cerevisiae" is further suitable as for this task as they produce the necessary reactants for wax syntheses to create wax esters. Scientists have investigated the possibility of expressing different wax synthase genes, including those of "A. baylyi" ADP1, "M. hydrocarbonoclasticus DSM 8798", "R. opacus PD630", "M. musculus C57BL/6" and "P. arcticus 273-4", in "S. cerevisiae", and found that that of "Marinobacter hydrocarbonoclasticus" DSM 8798 was the most effective since it showed highest relative preference for ethanol, thus allowing for the production of biodiesel fuels, in part taking advantage of the enzyme's promiscuous nature.
References.
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14543596
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Lovastatin nonaketide synthase
|
In enzymology, lovastatin nonaketide synthase (EC 2.3.1.161) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + 8 malonyl-CoA + 11 NADPH + 10 H+ + S-adenosyl-L-methionine formula_0 dihydromonacolin L + 9 CoA + 8 CO2 + 11 NADP+ + S-adenosyl-L-homocysteine + 6 H2O
The 5 substrates of this enzyme are acetyl-CoA, malonyl-CoA, NADPH, H+, and S-adenosyl-L-methionine, whereas its 6 products are dihydromonacolin L, CoA, CO2, NADP+, S-adenosyl-L-homocysteine, and H2O.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acyl-CoA:malonyl-CoA C-acyltransferase (decarboxylating, oxoacyl- and enoyl-reducing, thioester-hydrolysing).
References.
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14543619
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Lysine N-acetyltransferase
|
Class of enzymes
In enzymology, a lysine N-acetyltransferase (EC 2.3.1.32) is an enzyme that catalyzes the chemical reaction
acetyl phosphate + L-lysine formula_0 phosphate + N6-acetyl-L-lysine
Thus, the two substrates of this enzyme are acetyl phosphate and L-lysine, whereas its two products are phosphate and N6-acetyl-L-lysine.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-phosphate:L-lysine N6-acetyltransferase. Other names in common use include lysine acetyltransferase, and acetyl-phosphate:L-lysine 6-N-acetyltransferase. This enzyme participates in lysine degradation.
References.
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14543633
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Lysyltransferase
|
In enzymology, a lysyltransferase (EC 2.3.2.3) is an enzyme that catalyzes the chemical reaction
L-lysyl-tRNA + phosphatidylglycerol formula_0 tRNA + 3-phosphatidyl-1'-(3'-O-L-lysyl)glycerol
Thus, the two substrates of this enzyme are L-lysyl-tRNA and phosphatidylglycerol, whereas its two products are tRNA and 3-phosphatidyl-1'-(3'-O-L-lysyl)glycerol.
This enzyme belongs to the family of transferases, specifically the aminoacyltransferases. The systematic name of this enzyme class is L-lysyl-tRNA:phosphatidylglycerol 3-O-lysyltransferase.
References.
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14543654
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Malate synthase
|
Class of enzymes
In enzymology, a malate synthase (EC 2.3.3.9) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + H2O + glyoxylate formula_0 ("S")-malate + CoA
The 3 substrates of this enzyme are acetyl-CoA, H2O, and glyoxylate, whereas its two products are ("S")-malate and CoA. This enzyme participates in pyruvate metabolism and glyoxylate and dicarboxylate metabolism.
Nomenclature.
This enzyme belongs to the family of transferases, specifically acyltransferases that convert acyl groups into alkyl groups on transfer. The systematic name of this enzyme class is acetyl-CoA:glyoxylate C-acetyltransferase (thioester-hydrolysing, carboxymethyl-forming). Other names in common use include L-malate glyoxylate-lyase (CoA-acetylating), glyoxylate transacetylase, glyoxylate transacetase, glyoxylic transacetase, malate condensing enzyme, malate synthetase, malic synthetase, and malic-condensing enzyme.
Structure.
Malate synthases fall into two major families, isoforms A and G. Isoform G is monomeric with a size of about 80-kD and found exclusively in bacteria. Isoform A is about 65 kD per subunit and can form homomultimers in eukaryotes. This enzyme contains a central TIM barrel sandwiched between an N-terminal alpha-helical clasp and an alpha/beta domain stemming from two insertions into the TIM barrel sequence. The enzyme terminates with a C-terminal five-helix plug. The active site, where the acetyl-CoA and glyoxylate bind to the enzyme, lies between the TIM barrel and C-terminal plug. Upon binding, the acetyl-CoA molecule forms a J-shape inserted into the binding pocket, by an intramolecular hydrogen bond between N7 of the adenine ring and a hydroxyl group on the pantetheine tail. In addition, a critical magnesium ion within the active site coordinates with glyoxylate, glutamic acid 427, aspartic acid 455, and two water molecules. The amino acids interacting with acetyl CoA upon binding are highly conserved. Sequence identity is high within each class of isoforms, but between both classes sequence identity drops to about 15%. The alpha/beta domain, which has no apparent function, is not seen in isoform A.
Mechanism.
The mechanism of malate synthase is an aldol reaction followed by thioester hydrolysis. Initially, aspartate 631 acts as a catalytic base, abstracting a proton from the alpha carbon of acetyl-CoA and creating an enolate that is stabilized by arginine 338. This is considered to be the rate-determining step of the mechanism. Then, the newly formed enolate acts as a nucleophile that attacks the aldehyde of glyoxylate, imparting a negative charge on the oxygen which is stabilized by arginine 338 and the coordinating magnesium cation. This malyl-CoA intermediate then undergoes hydrolysis at the acyl-CoA portion, generating a carboxylate anion. The enzyme finally releases malate and coenzyme A.
Function.
The citric acid cycle (also known as the tricarboxylic acid cycle or the Krebs cycle) is used by aerobic organisms to produce energy via the oxidation of acetyl-CoA, which is derived from pyruvate (a product of glycolysis). The citric acid cycle accepts acetyl-CoA and metabolizes it to form carbon dioxide. A related cycle, called the glyoxylate cycle, is found in many bacteria and plants. In plants, the glyoxylate cycle takes place in glyoxysomes. In this cycle, isocitrate lyase and malate synthase skip over the decarboxylation steps of the citric acid cycle. In other words, malate synthase works together with isocitrate lyase in the glyoxylate cycle to bypass two oxidative steps of Krebs cycle and permit carbon incorporation from acetate or fatty acids in many microorganisms. Together, these two enzymes serve to produce succinate (which exits the cycle to be used for synthesis of sugars) and malate (which remains in the glyoxylate cycle). During this process, acetyl-CoA and water are used as substrates. As a result, the cell does not lose 2 molecules of carbon dioxide as it does in the Krebs cycle. The glyoxylate cycle, facilitated by malate synthase and isocitrate lyase, allows plants and bacteria to subsist on acetyl-CoA or other two carbon compounds. For example, "Euglena gracilis", a single-celled eukaryotic alga, consumes ethanol to form acetyl-CoA and subsequently, carbohydrates. Within germinating plants, the glyoxylate cycle allows the conversion of reserve lipids into carbohydrates within glyoxysomes.
Evolutionary history.
Malate synthase is found as an octamer of identical subunits (each roughly 60kDa) in some plants, including maize. It is found as a homotetramer in the fungus "Candida" and as a homodimer in eubacteria. Malate synthase is fused to the C-terminus of isocitrate lyase in "C. elegans", resulting in a single bifunctional protein. While there is currently not sufficient sequence information to determine the exact evolutionary history of malate synthase, plant, fungal, and "C. elegans" sequences are distinct and show no homologues from archaebacteria.
Activity in humans.
Traditionally, malate synthases are described in bacteria as part of the glyoxylate cycle, and malate synthase activity had not been reported for a human protein prior to a study by Strittmatter, et al. In this study, CLYBL was found to be a human mitochondrial enzyme with malate synthase activity. It is found in multiple eukaryotic taxa and is conserved in bacteria. CLYBL differs from other malate synthases in that it lacks a large portion of the C-terminal domain and shows lower specific activity and efficiency. CLYBL is linked to the vitamin B12 metabolism pathway because it is strongly co-expressed with MUT, MMAA, and MMAB, three members of the mitochondrial B12 pathway. Furthermore, a loss of function polymorphism, that leads to a loss of the CLYBL protein, is simultaneously associated with low levels of B12 in human plasma. While the exact mechanism of CLYBL’s involvement in B12 metabolism is not well understood, it is thought to convert citramalyl-CoA into pyruvate and acetyl-CoA. Without this conversion, itaconyl-CoA, a precursor to citramalyl-CoA, builds up in the cell leads to the inactivation of vitamin B12. This inactivation inhibits the methionine cycle, which leads to reduced serine, glycine, one-carbon, and folate metabolism.
Clinical significance.
Because the glyoxylate cycle occurs in bacteria and fungi, studying the mechanisms of malate synthase (as well as isocitrate lyase) is important for understanding human, animal, and plant pathogenesis. Studying malate synthase can shed light on the metabolic pathways that allow pathogens to survive inside a host as well as elucidate possible treatments. Many studies have been conducted on malate synthase activity in pathogens, including "Mycobacterium tuberculosis", "Pseudomonas aeruginosa", "Brucella melitensis", and "Escherichia coli".
"Mycobacterium tuberculosis".
Malate synthase and the glyoxylate pathway is especially important to "M. tuberculosis", allowing long-term persistence of its infection. When cells of "M. tuberculosis" become phagocytosed, the bacterium upregulates genes encoding the glyoxylate shunt enzymes. "Mycobacterium tuberculosis" is one of the most well studied pathogens in connection to the enzyme malate synthase. The structure and kinetics of "Mycobacterium tuberculosis" malate synthase have been well categorized. Malate synthase is essential to "Mycobacterium tuberculosis" survival because it allows the bacteria to assimilate acetyl-CoA into long-chain carbohydrates and survive in harsh environments. Beyond this, malate synthase prevents toxicity from buildup of glyoxylate produced by isocitrate lyase. Downregulation of malate synthase results in reduced stress tolerance, persistence, and growth of "Mycobacterium tuberculosis" inside macrophages. The enzyme can be inhibited by small molecules (although inhibition is microenvironment dependent), which suggests that these may be used as new chemotherapies.
"Pseudomonas aeruginosa".
"Pseudomonas aeruginosa" causes severe infections in humans and is labeled as a critical threat by the World Health Organization because of its resistance to multiple therapies. The glyoxylate shunt is essential for "Pseudomonas aeruginosa" growth in a host organism. In 2017, McVey, et al. examined the 3D structure of "P. aeruginosa" malate synthase G. They found that it is a monomer composed of four domains and is highly conserved in other pathogens. They further utilized computational analysis to identify two binding pockets that may serve as drug targets.
"Brucella melitensis".
"Brucella melitensis" is a pathogenic bacterium that causes fever and inflammation of the epididymis in sheep and cattle and can be transmitted to humans through the consumption of unpasteurized milk. Malate synthase has been identified as a potential virulence factor in this bacterium. In 2016, Adi, et al. constructed a 3D crystallized structure of the protein to identify catalytic domains and investigate potential inhibitors. They identified five inhibitors with non-oral toxicity that served as drugs against the bacteria, suggesting possible treatment routes for brucellosis.
"Escherichia coli".
In "Escherichia coli", the genes encoding the enzymes required for the glyoxylate cycle are expressed from the polycistronic ace operon. This operon contains genes coding for malate synthase (aceB), isocitrate lyase (aceA), and isocitrate dehydrogenase kinase/phosphatase (aceK).
Structural Studies.
As of early 2018, several structures have been solved for malate synthases, including those with PDB accession codes 2GQ3, 1D8C, 3OYX, 3PUG, 5TAO, 5H8M, 2JQX, 1P7T, and 1Y8B.
References.
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14543677
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Maltose O-acetyltransferase
|
In enzymology, a maltose O-acetyltransferase (EC 2.3.1.79) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + maltose formula_0 CoA + 6-O-acetyl-alpha-D-glucopyranosyl-(1->4)-D-glucose
Thus, the two substrates of this enzyme are acetyl-CoA and maltose, whereas its two products are CoA and 6-O-acetyl-alpha-D-glucopyranosyl-(1->4)-D-glucose.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:maltose O-acetyltransferase. Other names in common use include maltose transacetylase, maltose O-acetyltransferase, and MAT.
Structural studies.
As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes 1OCX, 2IC7, and 2P2O.
References.
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14543692
|
Monoterpenol O-acetyltransferase
|
In enzymology, a monoterpenol O-acetyltransferase (EC 2.3.1.69) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + a monoterpenol formula_0 CoA + a monoterpenol acetate ester
Thus, the two substrates of this enzyme are acetyl-CoA and monoterpenol, whereas its two products are CoA and monoterpenol acetate ester.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:monoterpenol O-acetyltransferase. This enzyme is also called menthol transacetylase.
References.
<templatestyles src="Reflist/styles.css" />
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
}
] |
https://en.wikipedia.org/wiki?curid=14543692
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14543706
|
Mycocerosate synthase
|
In enzymology, a mycocerosate synthase (EC 2.3.1.111) is an enzyme that catalyzes the chemical reaction
acyl-CoA + n methylmalonyl-CoA + 2n NADPH + 2n H+ formula_0 multi-methyl-branched acyl-CoA + n CoA + n CO2 + 2n NADP+
The 4 substrates of this enzyme are acyl-CoA, methylmalonyl-CoA, NADPH, and H+, whereas its 4 products are multi-methyl-branched acyl-CoA, CoA, CO2, and NADP+.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acyl-CoA:methylmalonyl-CoA C-acyltransferase (decarboxylating, oxoacyl- and enoyl-reducing). This enzyme is also called mycocerosic acid synthase.
References.
<templatestyles src="Reflist/styles.css" />
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
}
] |
https://en.wikipedia.org/wiki?curid=14543706
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14543716
|
(myelin-proteolipid) O-palmitoyltransferase
|
Class of enzymes
In enzymology, a [myelin-proteolipid] O-palmitoyltransferase (EC 2.3.1.100) is an enzyme that catalyzes the chemical reaction
palmitoyl-CoA + [myelin proteolipid] formula_0 CoA + O-palmitoyl-[myelin proteolipid]
Thus, the two substrates of this enzyme are palmitoyl-CoA and myelin proteolipid, whereas its two products are CoA and O-palmitoyl-myelin proteolipid.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is palmitoyl-CoA:[myelin-proteolipid] O-palmitoyltransferase. Other names in common use include myelin PLP acyltransferase, acyl-protein synthetase, and myelin-proteolipid O-palmitoyltransferase.
References.
<templatestyles src="Reflist/styles.css" />
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
}
] |
https://en.wikipedia.org/wiki?curid=14543716
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14543729
|
N6-hydroxylysine O-acetyltransferase
|
In enzymology, a N6-hydroxylysine O-acetyltransferase (EC 2.3.1.102) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + N6-hydroxy-L-lysine formula_0 CoA + N6-acetyl-N6-hydroxy-L-lysine
Thus, the two substrates of this enzyme are acetyl-CoA and N6-hydroxy-L-lysine, whereas its two products are CoA and N6-acetyl-N6-hydroxy-L-lysine.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:N6-hydroxy-L-lysine 6-acetyltransferase. Other names in common use include N6-hydroxylysine:acetyl CoA N6-transacetylase, N6-hydroxylysine acetylase, and acetyl-CoA:6-N-hydroxy-L-lysine 6-acetyltransferase. This enzyme participates in lysine degradation.
References.
<templatestyles src="Reflist/styles.css" />
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
}
] |
https://en.wikipedia.org/wiki?curid=14543729
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14543896
|
N-acetylneuraminate 4-O-acetyltransferase
|
In enzymology, a N-acetylneuraminate 4-O-acetyltransferase (EC 2.3.1.44) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + N-acetylneuraminate formula_0 CoA + N-acetyl-4-O-acetylneuraminate
Thus, the two substrates of this enzyme are acetyl-CoA and N-acetylneuraminate, whereas its two products are CoA and N-acetyl-4-O-acetylneuraminate.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:N-acetylneuraminate 4-O-acetyltransferase. This enzyme is also called sialate O-acetyltransferase.
References.
<templatestyles src="Reflist/styles.css" />
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
}
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https://en.wikipedia.org/wiki?curid=14543896
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14543916
|
N-acetylneuraminate 7-O(or 9-O)-acetyltransferase
|
In enzymology, a N-acetylneuraminate 7-O(or 9-O)-acetyltransferase (EC 2.3.1.45) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + N-acetylneuraminate formula_0 CoA + N-acetyl-7-O(or 9-O)-acetylneuraminate
Thus, the two substrates of this enzyme are acetyl-CoA and N-acetylneuraminate, whereas its 3 products are CoA, N-acetyl-7-O-acetylneuraminate, and N-acetyl-9-O-acetylneuraminate.
Nomenclature.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:N-acetylneuraminate 7-O(or 9-O)-acetyltransferase. Other names in common use include N-acetylneuraminate 7(8)-O-acetyltransferase, sialate O-acetyltransferase, N-acetylneuraminate 7,8-O-acetyltransferase, acetyl-CoA:N-acetylneuraminate-7- or 8-O-acetyltransferase, acetyl-CoA:N-acetylneuraminate-7- and/or 8-O-acetyltransferase, glycoprotein 7(9)-O-acetyltransferase, acetyl-CoA:N-acetylneuraminate-9(7)-O-acetyltransferase, N-acetylneuraminate O7-(or O9-)acetyltransferase, and acetyl-CoA:N-acetylneuraminate-9(or 7)-O-acetyltransferase.
References.
<templatestyles src="Reflist/styles.css" />
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
}
] |
https://en.wikipedia.org/wiki?curid=14543916
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14543957
|
N-hydroxyarylamine O-acetyltransferase
|
In enzymology, a N-hydroxyarylamine O-acetyltransferase (EC 2.3.1.118) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + an N-hydroxyarylamine formula_0 CoA + an N-acetoxyarylamine
Thus, the two substrates of this enzyme are acetyl-CoA and N-hydroxyarylamine, whereas its two products are CoA and N-acetoxyarylamine.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:N-hydroxyarylamine O-acetyltransferase. Other names in common use include arylhydroxamate N,O-acetyltransferase, arylamine N-acetyltransferase, and N-hydroxy-2-aminofluorene-O-acetyltransferase.
Structural studies.
As of late 2007, only one structure has been solved for this class of enzymes, with the PDB accession code 1E2T.
References.
<templatestyles src="Reflist/styles.css" />
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
}
] |
https://en.wikipedia.org/wiki?curid=14543957
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14543981
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Ornithine N-benzoyltransferase
|
In enzymology, an ornithine N-benzoyltransferase (EC 2.3.1.127) is an enzyme that catalyzes the chemical reaction
2 benzoyl-CoA + L-ornithine formula_0 2 CoA + N2,N5-dibenzoyl-L-ornithine
Thus, the two substrates of this enzyme are benzoyl-CoA and L-ornithine, whereas its two products are CoA and N2,N5-dibenzoyl-L-ornithine.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is benzoyl-CoA:L-ornithine N-benzoyltransferase. This enzyme is also called ornithine N-acyltransferase.
References.
<templatestyles src="Reflist/styles.css" />
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
}
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https://en.wikipedia.org/wiki?curid=14543981
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14543996
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Peptide alpha-N-acetyltransferase
|
Class of enzyme
In enzymology, a peptide alpha-N-acetyltransferase (EC 2.3.1.88) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + peptide formula_0 Nalpha-acetylpeptide + CoA
Thus, the two substrates of this enzyme are acetyl-CoA and peptide, whereas its two products are Nalpha-acetylpeptide and CoA.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:peptide Nalpha-acetyltransferase. Other names in common use include beta-endorphin acetyltransferase, peptide acetyltransferase, protein N-terminal acetyltransferase, NAT, Nalpha-acetyltransferase, amino-terminal amino acid-acetylating enzyme, and acetyl-CoA:peptide alpha-N-acetyltransferase.
Structural studies.
As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes 2OB0 and 2PSW.
References.
<templatestyles src="Reflist/styles.css" />
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
}
] |
https://en.wikipedia.org/wiki?curid=14543996
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145440
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Rare-earth element
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Any of the fifteen lanthanides plus scandium and yttrium
Rare-earth elementsin the periodic table
The rare-earth elements (REE), also called the rare-earth metals or rare earths or, in context, rare-earth oxides, and sometimes the lanthanides (although scandium and yttrium, which do not belong to this series, are usually included as rare earths), are a set of 17 nearly indistinguishable lustrous silvery-white soft heavy metals. Compounds containing rare earths have diverse applications in electrical and electronic components, lasers, glass, magnetic materials, and industrial processes.
Scandium and yttrium are considered rare-earth elements because they tend to occur in the same ore deposits as the lanthanides and exhibit similar chemical properties, but have different electrical and magnetic properties. The term 'rare-earth' is a misnomer because they are not actually scarce, although historically it took a long time to isolate these elements.
These metals tarnish slowly in air at room temperature and react slowly with cold water to form hydroxides, liberating hydrogen. They react with steam to form oxides and ignite spontaneously at a temperature of . These elements and their compounds have no biological function other than in several specialized enzymes, such as in lanthanide-dependent methanol dehydrogenases in bacteria. The water-soluble compounds are mildly to moderately toxic, but the insoluble ones are not. All isotopes of promethium are radioactive, and it does not occur naturally in the earth's crust, except for a trace amount generated by spontaneous fission of uranium-238. They are often found in minerals with thorium, and less commonly uranium.
Though rare-earth elements are technically relatively plentiful in the entire Earth's crust (cerium being the 25th-most-abundant element at 68 parts per million, more abundant than copper), in practice this is spread thin across trace impurities, so to obtain rare earths at usable purity requires processing enormous amounts of raw ore at great expense, thus the name "rare" earths.
Because of their geochemical properties, rare-earth elements are typically dispersed and not often found concentrated in rare-earth minerals. Consequently, economically exploitable ore deposits are sparse. The first rare-earth mineral discovered (1787) was gadolinite, a black mineral composed of cerium, yttrium, iron, silicon, and other elements. This mineral was extracted from a mine in the village of Ytterby in Sweden; four of the rare-earth elements bear names derived from this single location.
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Minerals.
A table listing the 17 rare-earth elements, their atomic number and symbol, the etymology of their names, and their main uses (see also Applications of lanthanides) is provided here. Some of the rare-earth elements are named after the scientists who discovered them, or elucidated their elemental properties, and some after the geographical locations where discovered.
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A mnemonic for the names of the sixth-row elements in order is "Lately college parties never produce sexy European girls that drink heavily even though you look".
Discovery and early history.
Rare earths were mainly discovered as components of minerals. Ytterbium was found in the "ytterbite" (renamed to gadolinite in 1800) discovered by Lieutenant Carl Axel Arrhenius in 1787 at a quarry in the village of Ytterby, Sweden and termed "rare" because it had never yet been seen. Arrhenius's "ytterbite" reached Johan Gadolin, a Royal Academy of Turku professor, and his analysis yielded an unknown oxide ("earth" in the geological parlance of the day), which he called yttria. Anders Gustav Ekeberg isolated beryllium from the gadolinite but failed to recognize other elements in the ore. After this discovery in 1794, a mineral from Bastnäs near Riddarhyttan, Sweden, which was believed to be an iron–tungsten mineral, was re-examined by Jöns Jacob Berzelius and Wilhelm Hisinger. In 1803 they obtained a white oxide and called it ceria. Martin Heinrich Klaproth independently discovered the same oxide and called it "ochroia". It took another 30 years for researchers to determine that other elements were contained in the two ores ceria and yttria (the similarity of the rare-earth metals' chemical properties made their separation difficult).
In 1839 Carl Gustav Mosander, an assistant of Berzelius, separated ceria by heating the nitrate and dissolving the product in nitric acid. He called the oxide of the soluble salt "lanthana". It took him three more years to separate the lanthana further into "didymia" and pure lanthana. Didymia, although not further separable by Mosander's techniques, was in fact still a mixture of oxides.
In 1842 Mosander also separated the yttria into three oxides: pure yttria, terbia, and erbia (all the names are derived from the town name "Ytterby"). The earth giving pink salts he called "terbium"; the one that yielded yellow peroxide he called "erbium".
In 1842 the number of known rare-earth elements had reached six: yttrium, cerium, lanthanum, didymium, erbium, and terbium.
Nils Johan Berlin and Marc Delafontaine tried also to separate the crude yttria and found the same substances that Mosander obtained, but Berlin named (1860) the substance giving pink salts "erbium", and Delafontaine named the substance with the yellow peroxide "terbium". This confusion led to several false claims of new elements, such as the "mosandrium" of J. Lawrence Smith, or the "philippium" and "decipium" of Delafontaine. Due to the difficulty in separating the metals (and determining the separation is complete), the total number of false discoveries was dozens, with some putting the total number of discoveries at over a hundred.
Spectroscopic identification.
There were no further discoveries for 30 years, and the element didymium was listed in the periodic table of elements with a molecular mass of 138. In 1879, Delafontaine used the new physical process of optical flame spectroscopy and found several new spectral lines in didymia. Also in 1879, Paul Émile Lecoq de Boisbaudran isolated the new element "samarium" from the mineral samarskite.
The samaria earth was further separated by Lecoq de Boisbaudran in 1886, and a similar result was obtained by Jean Charles Galissard de Marignac by direct isolation from samarskite. They named the element "gadolinium" after Johan Gadolin, and its oxide was named "gadolinia".
Further spectroscopic analysis between 1886 and 1901 of samaria, yttria, and samarskite by William Crookes, Lecoq de Boisbaudran and Eugène-Anatole Demarçay yielded several new spectral lines that indicated the existence of an unknown element. The fractional crystallization of the oxides then yielded "europium" in 1901.
In 1839 the third source for rare earths became available. This is a mineral similar to gadolinite called "uranotantalum" (now called "samarskite") an oxide of a mixture of elements such as yttrium, ytterbium, iron, uranium, thorium, calcium, niobium, and tantalum. This mineral from Miass in the southern Ural Mountains was documented by Gustav Rose. The Russian chemist R. Harmann proposed that a new element he called "ilmenium" should be present in this mineral, but later, Christian Wilhelm Blomstrand, Galissard de Marignac, and Heinrich Rose found only tantalum and niobium (columbium) in it.
The exact number of rare-earth elements that existed was highly unclear, and a maximum number of 25 was estimated. The use of X-ray spectra (obtained by X-ray crystallography) by Henry Gwyn Jeffreys Moseley made it possible to assign atomic numbers to the elements. Moseley found that the exact number of lanthanides had to be 15, but that element 61 had not yet been discovered. (This is promethium, a radioactive element whose most stable isotope has a half-life of just 18 years.)
Using these facts about atomic numbers from X-ray crystallography, Moseley also showed that hafnium (element 72) would not be a rare-earth element. Moseley was killed in World War I in 1915, years before hafnium was discovered. Hence, the claim of Georges Urbain that he had discovered element 72 was untrue. Hafnium is an element that lies in the periodic table immediately below zirconium, and hafnium and zirconium have very similar chemical and physical properties.
Sources and purification.
During the 1940s, Frank Spedding and others in the United States (during the Manhattan Project) developed chemical ion-exchange procedures for separating and purifying rare-earth elements. This method was first applied to the actinides for separating plutonium-239 and neptunium from uranium, thorium, actinium, and the other actinides in the materials produced in nuclear reactors. Plutonium-239 was very desirable because it is a fissile material.
The principal sources of rare-earth elements are the minerals bastnäsite (, where R is a mixture of rare-earth elements), monazite (, where X is a mixture of rare-earth elements and sometimes thorium), and loparite (), and the lateritic ion-adsorption clays. Despite their high relative abundance, rare-earth minerals are more difficult to mine and extract than equivalent sources of transition metals (due in part to their similar chemical properties), making the rare-earth elements relatively expensive. Their industrial use was very limited until efficient separation techniques were developed, such as ion exchange, fractional crystallization, and liquid–liquid extraction during the late 1950s and early 1960s.
Some ilmenite concentrates contain small amounts of scandium and other rare-earth elements, which could be analysed by X-ray fluorescence (XRF).
Classification.
Before the time that ion exchange methods and elution were available, the separation of the rare earths was primarily achieved by repeated precipitation or crystallization. In those days, the first separation was into two main groups, the cerium earths (lanthanum, cerium, praseodymium, neodymium, and samarium) and the yttrium earths (scandium, yttrium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium). Europium, gadolinium, and terbium were either considered as a separate group of rare-earth elements (the terbium group), or europium was included in the cerium group, and gadolinium and terbium were included in the yttrium group. In the latter case, the f-block elements are split into half: the first half (La–Eu) form the cerium group, and the second half (Gd–Yb) together with group 3 (Sc, Y, Lu) form the yttrium group. The reason for this division arose from the difference in solubility of rare-earth double sulfates with sodium and potassium. The sodium double sulfates of the cerium group are poorly soluble, those of the terbium group slightly, and those of the yttrium group are very soluble. Sometimes, the yttrium group was further split into the erbium group (dysprosium, holmium, erbium, and thulium) and the ytterbium group (ytterbium and lutetium), but today the main grouping is between the cerium and the yttrium groups. Today, the rare-earth elements are classified as light or heavy rare-earth elements, rather than in cerium and yttrium groups.
Light versus heavy classification.
The classification of rare-earth elements is inconsistent between authors. The most common distinction between rare-earth elements is made by atomic numbers; those with low atomic numbers are referred to as light rare-earth elements (LREE), those with high atomic numbers are the heavy rare-earth elements (HREE), and those that fall in between are typically referred to as the middle rare-earth elements (MREE). Commonly, rare-earth elements with atomic numbers 57 to 61 (lanthanum to promethium) are classified as light and those with atomic numbers 62 and greater are classified as heavy rare-earth elements. Increasing atomic numbers between light and heavy rare-earth elements and decreasing atomic radii throughout the series causes chemical variations. Europium is exempt of this classification as it has two valence states: Eu2+ and Eu3+. Yttrium is grouped as heavy rare-earth element due to chemical similarities. The break between the two groups is sometimes put elsewhere, such as between elements 63 (europium) and 64 (gadolinium). The actual metallic densities of these two groups overlap, with the "light" group having densities from 6.145 (lanthanum) to 7.26 (promethium) or 7.52 (samarium) g/cc, and the "heavy" group from 6.965 (ytterbium) to 9.32 (thulium), as well as including yttrium at 4.47. Europium has a density of 5.24.
Origin.
Rare-earth elements, except scandium, are heavier than iron and thus are produced by supernova nucleosynthesis or by the s-process in asymptotic giant branch stars. In nature, spontaneous fission of uranium-238 produces trace amounts of radioactive promethium, but most promethium is synthetically produced in nuclear reactors.
Due to their chemical similarity, the concentrations of rare earths in rocks are only slowly changed by geochemical processes, making their proportions useful for geochronology and dating fossils.
Compounds.
Rare-earth elements occur in nature in combination with phosphate (monazite), carbonate-fluoride (bastnäsite), and oxygen anions.
In their oxides, most rare-earth elements only have a valence of 3 and form sesquioxides (cerium forms ). Five different crystal structures are known, depending on the element and the temperature. The X-phase and the H-phase are only stable above 2000 K. At lower temperatures, there are the hexagonal A-phase, the monoclinic B-phase, and the cubic C-phase, which is the stable form at room temperature for most of the elements. The C-phase was once thought to be in space group "I"213 (no. 199), but is now known to be in space group "Ia"3 (no. 206). The structure is similar to that of fluorite or cerium dioxide (in which the cations form a face-centred cubic lattice and the anions sit inside the tetrahedra of cations), except that one-quarter of the anions (oxygen) are missing. The unit cell of these sesquioxides corresponds to eight unit cells of fluorite or cerium dioxide, with 32 cations instead of 4. This is called the bixbyite structure, as it occurs in a mineral of that name ().
Geological distribution.
As seen in the chart, rare-earth elements are found on Earth at similar concentrations to many common transition metals. The most abundant rare-earth element is cerium, which is actually the 25th most abundant element in Earth's crust, having 68 parts per million (about as common as copper). The exception is the highly unstable and radioactive promethium "rare earth" is quite scarce. The longest-lived isotope of promethium has a half-life of 17.7 years, so the element exists in nature in only negligible amounts (approximately 572 g in the entire Earth's crust). Promethium is one of the two elements that do not have stable (non-radioactive) isotopes and are followed by (i.e. with higher atomic number) stable elements (the other being technetium).
The rare-earth elements are often found together. During the sequential accretion of the Earth, the dense rare-earth elements were incorporated into the deeper portions of the planet. Early differentiation of molten material largely incorporated the rare earths into mantle rocks. The high field strength and large ionic radii of rare earths make them incompatible with the crystal lattices of most rock-forming minerals, so REE will undergo strong partitioning into a melt phase if one is present. REE are chemically very similar and have always been difficult to separate, but the gradual decrease in ionic radius from light REE (LREE) to heavy REE (HREE), called the lanthanide contraction, can produce a broad separation between light and heavy REE. The larger ionic radii of LREE make them generally more incompatible than HREE in rock-forming minerals, and will partition more strongly into a melt phase, while HREE may prefer to remain in the crystalline residue, particularly if it contains HREE-compatible minerals like garnet. The result is that all magma formed from partial melting will always have greater concentrations of LREE than HREE, and individual minerals may be dominated by either HREE or LREE, depending on which range of ionic radii best fits the crystal lattice.
Among the anhydrous rare-earth phosphates, it is the tetragonal mineral xenotime that incorporates yttrium and the HREE, whereas the monoclinic monazite phase incorporates cerium and the LREE preferentially. The smaller size of the HREE allows greater solid solubility in the rock-forming minerals that make up Earth's mantle, and thus yttrium and the HREE show less enrichment in Earth's crust relative to chondritic abundance than does cerium and the LREE. This has economic consequences: large ore bodies of LREE are known around the world and are being exploited. Ore bodies for HREE are more rare, smaller, and less concentrated. Most of the current supply of HREE originates in the "ion-absorption clay" ores of Southern China. Some versions provide concentrates containing about 65% yttrium oxide, with the HREE being present in ratios reflecting the Oddo–Harkins rule: even-numbered REE at abundances of about 5% each, and odd-numbered REE at abundances of about 1% each. Similar compositions are found in xenotime or gadolinite.
Well-known minerals containing yttrium, and other HREE, include gadolinite, xenotime, samarskite, euxenite, fergusonite, yttrotantalite, yttrotungstite, yttrofluorite (a variety of fluorite), thalenite, and yttrialite. Small amounts occur in zircon, which derives its typical yellow fluorescence from some of the accompanying HREE. The zirconium mineral eudialyte, such as is found in southern Greenland, contains small but potentially useful amounts of yttrium. Of the above yttrium minerals, most played a part in providing research quantities of lanthanides during the discovery days. Xenotime is occasionally recovered as a byproduct of heavy-sand processing, but is not as abundant as the similarly recovered monazite (which typically contains a few percent of yttrium). Uranium ores from Ontario have occasionally yielded yttrium as a byproduct.
Well-known minerals containing cerium, and other LREE, include bastnäsite, monazite, allanite, loparite, ancylite, parisite, lanthanite, chevkinite, cerite, stillwellite, britholite, fluocerite, and cerianite. Monazite (marine sands from Brazil, India, or Australia; rock from South Africa), bastnäsite (from Mountain Pass rare earth mine, or several localities in China), and loparite (Kola Peninsula, Russia) have been the principal ores of cerium and the light lanthanides.
Enriched deposits of rare-earth elements at the surface of the Earth, carbonatites and pegmatites, are related to alkaline plutonism, an uncommon kind of magmatism that occurs in tectonic settings where there is rifting or that are near subduction zones. In a rift setting, the alkaline magma is produced by very small degrees of partial melting (<1%) of garnet peridotite in the upper mantle (200 to 600 km depth). This melt becomes enriched in incompatible elements, like the rare-earth elements, by leaching them out of the crystalline residue. The resultant magma rises as a diapir, or diatreme, along pre-existing fractures, and can be emplaced deep in the crust, or erupted at the surface. Typical REE enriched deposits types forming in rift settings are carbonatites, and A- and M-Type granitoids. Near subduction zones, partial melting of the subducting plate within the asthenosphere (80 to 200 km depth) produces a volatile-rich magma (high concentrations of CO2 and water), with high concentrations of alkaline elements, and high element mobility that the rare earths are strongly partitioned into. This melt may also rise along pre-existing fractures, and be emplaced in the crust above the subducting slab or erupted at the surface. REE-enriched deposits forming from these melts are typically S-Type granitoids.
Alkaline magmas enriched with rare-earth elements include carbonatites, peralkaline granites (pegmatites), and nepheline syenite. Carbonatites crystallize from CO2-rich fluids, which can be produced by partial melting of hydrous-carbonated lherzolite to produce a CO2-rich primary magma, by fractional crystallization of an alkaline primary magma, or by separation of a CO2-rich immiscible liquid from. These liquids are most commonly forming in association with very deep Precambrian cratons, like the ones found in Africa and the Canadian Shield. Ferrocarbonatites are the most common type of carbonatite to be enriched in REE, and are often emplaced as late-stage, brecciated pipes at the core of igneous complexes; they consist of fine-grained calcite and hematite, sometimes with significant concentrations of ankerite and minor concentrations of siderite. Large carbonatite deposits enriched in rare-earth elements include Mount Weld in Australia, Thor Lake in Canada, Zandkopsdrift in South Africa, and Mountain Pass in the USA. Peralkaline granites (A-Type granitoids) have very high concentrations of alkaline elements and very low concentrations of phosphorus; they are deposited at moderate depths in extensional zones, often as igneous ring complexes, or as pipes, massive bodies, and lenses. These fluids have very low viscosities and high element mobility, which allows for the crystallization of large grains, despite a relatively short crystallization time upon emplacement; their large grain size is why these deposits are commonly referred to as pegmatites. Economically viable pegmatites are divided into Lithium-Cesium-Tantalum (LCT) and Niobium-Yttrium-Fluorine (NYF) types; NYF types are enriched in rare-earth minerals. Examples of rare-earth pegmatite deposits include Strange Lake in Canada and Khaladean-Buregtey in Mongolia. Nepheline syenite (M-Type granitoids) deposits are 90% feldspar and feldspathoid minerals. They are deposited in small, circular massifs and contain high concentrations of rare-earth-bearing accessory minerals. For the most part, these deposits are small but important examples include Illimaussaq-Kvanefeld in Greenland, and Lovozera in Russia.
Rare-earth elements can also be enriched in deposits by secondary alteration either by interactions with hydrothermal fluids or meteoric water or by erosion and transport of resistate REE-bearing minerals. Argillization of primary minerals enriches insoluble elements by leaching out silica and other soluble elements, recrystallizing feldspar into clay minerals such kaolinite, halloysite, and montmorillonite. In tropical regions where precipitation is high, weathering forms a thick argillized regolith, this process is called supergene enrichment and produces laterite deposits; heavy rare-earth elements are incorporated into the residual clay by absorption. This kind of deposit is only mined for REE in Southern China, where the majority of global heavy rare-earth element production occurs. REE-laterites do form elsewhere, including over the carbonatite at Mount Weld in Australia. REE may also be extracted from placer deposits if the sedimentary parent lithology contains REE-bearing, heavy resistate minerals.
In 2011, Yasuhiro Kato, a geologist at the University of Tokyo who led a study of Pacific Ocean seabed mud, published results indicating the mud could hold rich concentrations of rare-earth minerals. The deposits, studied at 78 sites, came from "[h]ot plumes from hydrothermal vents pull[ing] these materials out of seawater and deposit[ing] them on the seafloor, bit by bit, over tens of millions of years. One square patch of metal-rich mud 2.3 kilometers wide might contain enough rare earths to meet most of the global demand for a year, Japanese geologists report in "Nature Geoscience"." "I believe that rare[-]earth resources undersea are much more promising than on-land resources," said Kato. "[C]oncentrations of rare earths were comparable to those found in clays mined in China. Some deposits contained twice as much heavy rare earths such as dysprosium, a component of magnets in hybrid car motors."
The global demand for rare-earth elements (REEs) is expected to increase more than fivefold by 2030.
Geochemistry.
The REE geochemical classification is usually done on the basis of their atomic weight. One of the most common classifications divides REE into 3 groups: light rare earths (LREE - from 57La to 60Nd), intermediate (MREE - from 62Sm to 67Ho) and heavy (HREE - from 68Er to 71Lu). REE usually appear as trivalent ions, except for Ce and Eu which can take the form of Ce4+ and Eu2+ depending on the redox conditions of the system. Consequentially, REE are characterized by a substantial identity in their chemical reactivity, which results in a serial behaviour during geochemical processes rather than being characteristic of a single element of the series. Sc, Y, and Lu can be electronically distinguished from the other rare earths because they do not have "f" valence electrons, whereas the others do, but the chemical behaviour is almost the same.
A distinguishing factor in the geochemical behaviour of the REE is linked to the so-called "lanthanide contraction" which represents a higher-than-expected decrease in the atomic/ionic radius of the elements along the series. This is determined by the variation of the shielding effect towards the nuclear charge due to the progressive filling of the 4"f" orbital which acts against the electrons of the 6"s" and 5"d" orbitals. The lanthanide contraction has a direct effect on the geochemistry of the lanthanides, which show a different behaviour depending on the systems and processes in which they are involved. The effect of the lanthanide contraction can be observed in the REE behaviour both in a CHARAC-type geochemical system (CHArge-and-RAdius-Controlled) where elements with similar charge and radius should show coherent geochemical behaviour, and in non-CHARAC systems, such as aqueous solutions, where the electron structure is also an important parameter to consider as the lanthanide contraction affects the ionic potential. A direct consequence is that, during the formation of coordination bonds, the REE behaviour gradually changes along the series. Furthermore, the lanthanide contraction causes the ionic radius of Ho3+ (0.901 Å) to be almost identical to that of Y3+ (0.9 Å), justifying the inclusion of the latter among the REE.
Applications.
The application of rare-earth elements to geology is important to understanding the petrological processes of igneous, sedimentary and metamorphic rock formation. In geochemistry, rare-earth elements can be used to infer the petrological mechanisms that have affected a rock due to the subtle atomic size differences between the elements, which causes preferential fractionation of some rare earths relative to others depending on the processes at work.
The geochemical study of the REE is not carried out on absolute concentrations – as it is usually done with other chemical elements – but on normalized concentrations in order to observe their serial behaviour. In geochemistry, rare-earth elements are typically presented in normalized "spider" diagrams, in which concentration of rare-earth elements are normalized to a reference standard and are then expressed as the logarithm to the base 10 of the value.
Commonly, the rare-earth elements are normalized to chondritic meteorites, as these are believed to be the closest representation of unfractionated Solar System material. However, other normalizing standards can be applied depending on the purpose of the study. Normalization to a standard reference value, especially of a material believed to be unfractionated, allows the observed abundances to be compared to the initial abundances of the element. Normalization also removes the pronounced 'zig-zag' pattern caused by the differences in abundance between even and odd atomic numbers. Normalization is carried out by dividing the analytical concentrations of each element of the series by the concentration of the same element in a given standard, according to the equation:
formula_0
where n indicates the normalized concentration, formula_1 the analytical concentration of the element measured in the sample, and formula_2 the concentration of the same element in the reference material.
It is possible to observe the serial trend of the REE by reporting their normalized concentrations against the atomic number. The trends that are observed in "spider" diagrams are typically referred to as "patterns", which may be diagnostic of petrological processes that have affected the material of interest.
According to the general shape of the patterns or thanks to the presence (or absence) of so-called "anomalies", information regarding the system under examination and the occurring geochemical processes can be obtained. The anomalies represent enrichment (positive anomalies) or depletion (negative anomalies) of specific elements along the series and are graphically recognizable as positive or negative "peaks" along the REE patterns. The anomalies can be numerically quantified as the ratio between the normalized concentration of the element showing the anomaly and the predictable one based on the average of the normalized concentrations of the two elements in the previous and next position in the series, according to the equation:
formula_3
where formula_4 is the normalized concentration of the element whose anomaly has to be calculated, formula_5 and formula_6 the normalized concentrations of the respectively previous and next elements along the series.
The rare-earth elements patterns observed in igneous rocks are primarily a function of the chemistry of the source where the rock came from, as well as the fractionation history the rock has undergone. Fractionation is in turn a function of the partition coefficients of each element. Partition coefficients are responsible for the fractionation of trace elements (including rare-earth elements) into the liquid phase (the melt/magma) into the solid phase (the mineral). If an element preferentially remains in the solid phase it is termed 'compatible', and if it preferentially partitions into the melt phase it is described as 'incompatible'. Each element has a different partition coefficient, and therefore fractionates into solid and liquid phases distinctly. These concepts are also applicable to metamorphic and sedimentary petrology.
In igneous rocks, particularly in felsic melts, the following observations apply: anomalies in europium are dominated by the crystallization of feldspars. Hornblende, controls the enrichment of MREE compared to LREE and HREE. Depletion of LREE relative to HREE may be due to the crystallization of olivine, orthopyroxene, and clinopyroxene. On the other hand, the depletion of HREE relative to LREE may be due to the presence of garnet, as garnet preferentially incorporates HREE into its crystal structure. The presence of zircon may also cause a similar effect.
In sedimentary rocks, rare-earth elements in clastic sediments are a representation of provenance. The rare-earth element concentrations are not typically affected by sea and river waters, as rare-earth elements are insoluble and thus have very low concentrations in these fluids. As a result, when sediment is transported, rare-earth element concentrations are unaffected by the fluid and instead the rock retains the rare-earth element concentration from its source.
Sea and river waters typically have low rare-earth element concentrations. However, aqueous geochemistry is still very important. In oceans, rare-earth elements reflect input from rivers, hydrothermal vents, and aeolian sources; this is important in the investigation of ocean mixing and circulation.
Rare-earth elements are also useful for dating rocks, as some radioactive isotopes display long half-lives. Of particular interest are the 138La-138Ce, 147Sm-143Nd, and 176Lu-176Hf systems.
Production.
Until 1948, most of the world's rare earths were sourced from placer sand deposits in India and Brazil. Through the 1950s, South Africa was the world's rare earth source, from a monazite-rich reef at the Steenkampskraal mine in Western Cape province. Through the 1960s until the 1980s, the Mountain Pass rare earth mine in California made the United States the leading producer. Today, the Indian and South African deposits still produce some rare-earth concentrates, but they were dwarfed by the scale of Chinese production. In 2017, China produced 81% of the world's rare-earth supply, mostly in Inner Mongolia, although it had only 36.7% of reserves. Australia was the second and only other major producer with 15% of world production. All of the world's heavy rare earths (such as dysprosium) come from Chinese rare-earth sources such as the polymetallic Bayan Obo deposit. The Browns Range mine, located 160 km south east of Halls Creek in northern Western Australia, was under development in 2018 and is positioned to become the first significant dysprosium producer outside of China.
Increased demand has strained supply, and there is growing concern that the world may soon face a shortage of the rare earths. In several years from 2009 worldwide demand for rare-earth elements is expected to exceed supply by 40,000 tonnes annually unless major new sources are developed. In 2013, it was stated that the demand for REEs would increase due to the dependence of the EU on these elements, the fact that rare-earth elements cannot be substituted by other elements and that REEs have a low recycling rate. Furthermore, due to the increased demand and low supply, future prices are expected to increase and there is a chance that countries other than China will open REE mines. REE is increasing in demand due to the fact that they are essential for new and innovative technology that is being created. These new products that need REEs to be produced are high-technology equipment such as smart phones, digital cameras, computer parts, semiconductors, etc. In addition, these elements are more prevalent in the following industries: renewable energy technology, military equipment, glass making, and metallurgy.
China.
These concerns have intensified due to the actions of China, the predominant supplier. Specifically, China has announced regulations on exports and a crackdown on smuggling. On September 1, 2009, China announced plans to reduce its export quota to 35,000 tons per year in 2010–2015 to conserve scarce resources and protect the environment. On October 19, 2010, "China Daily", citing an unnamed Ministry of Commerce official, reported that China will "further reduce quotas for rare-earth exports by 30 percent at most next year to protect the precious metals from over-exploitation." The government in Beijing further increased its control by forcing smaller, independent miners to merge into state-owned corporations or face closure. At the end of 2010, China announced that the first round of export quotas in 2011 for rare earths would be 14,446 tons, which was a 35% decrease from the previous first round of quotas in 2010. China announced further export quotas on 14 July 2011 for the second half of the year with total allocation at 30,184 tons with total production capped at 93,800 tonnes. In September 2011, China announced the halt in production of three of its eight major rare-earth mines, responsible for almost 40% of China's total rare-earth production. In March 2012, the US, EU, and Japan confronted China at WTO about these export and production restrictions. China responded with claims that the restrictions had environmental protection in mind. In August 2012, China announced a further 20% reduction in production.
The United States, Japan, and the European Union filed a joint lawsuit with the World Trade Organization in 2012 against China, arguing that China should not be able to deny such important exports.
In response to the opening of new mines in other countries (Lynas in Australia and Molycorp in the United States), prices of rare earths dropped.
The price of dysprosium oxide was US$994/kg in 2011, but dropped to US$265/kg by 2014.
On August 29, 2014, the WTO ruled that China had broken free-trade agreements, and the WTO said in the summary of key findings that "the overall effect of the foreign and domestic restrictions is to encourage domestic extraction and secure preferential use of those materials by Chinese manufacturers." China declared that it would implement the ruling on September 26, 2014, but would need some time to do so. By January 5, 2015, China had lifted all quotas from the export of rare earths, but export licenses will still be required.
In 2019, China supplied between 85% and 95% of the global demand for the 17 rare-earth powders, half of them sourced from Myanmar. After the 2021 military coup in that country, future supplies of critical ores were possibly constrained. Additionally, it was speculated that the PRC could again reduce rare-earth exports to counter-act economic sanctions imposed by the US and EU countries. Rare-earth metals serve as crucial materials for electric vehicle manufacturing and high-tech military applications.
Myanmar (Burma).
Kachin State in Myanmar is the world's largest source of rare earths. In 2021, China imported US$ of rare earths from Myanmar in December 2021, exceeding 20,000 tonnes. Rare earths were discovered near Pangwa in Chipwi Township along the China–Myanmar border in the late 2010s. As China has shut down domestic mines due to the detrimental environmental impact, it has largely outsourced rare-earth mining to Kachin State. Chinese companies and miners illegally set up operations in Kachin State without government permits, and instead circumvent the central government by working with a Border Guard Force militia under the Tatmadaw, formerly known as the New Democratic Army – Kachin, which has profited from this extractive industry. As of March 2022[ [update]], 2,700 mining collection pools scattered across 300 separate locations were found in Kachin State, encompassing the area of Singapore, and an exponential increase from 2016. Land has also been seized from locals to conduct mining operations.
Other countries.
As a result of the increased demand and tightening restrictions on exports of the metals from China, some countries are stockpiling rare-earth resources. Searches for alternative sources in Australia, Brazil, Canada, South Africa, Tanzania, Greenland, and the United States are ongoing. Mines in these countries were closed when China undercut world prices in the 1990s, and it will take a few years to restart production as there are many barriers to entry. Significant sites under development outside China include Steenkampskraal in South Africa, the world's highest grade rare earths and thorium mine, closed in 1963, but has been gearing to go back into production. Over 80% of the infrastructure is already complete. Other mines include the Nolans Project in Central Australia, the Bokan Mountain project in Alaska, the remote Hoidas Lake project in northern Canada, and the Mount Weld project in Australia. The Hoidas Lake project has the potential to supply about 10% of the $1 billion of REE consumption that occurs in North America every year. Vietnam signed an agreement in October 2010 to supply Japan with rare earths from its northwestern Lai Châu Province, however the deal was never realized due to disagreements.
The largest rare-earth deposit in the U.S. is at Mountain Pass, California, sixty miles south of Las Vegas. Originally opened by Molycorp, the deposit has been mined, off and on, since 1951. A second large deposit of REEs at Elk Creek in southeast Nebraska is under consideration by NioCorp Development Ltd who hopes to open a niobium, scandium, and titanium mine there. That mine may be able to produce as much as 7200 tonnes of ferro niobium and 95 tonnes of scandium trioxide annually, although, as of 2022, financing is still in the works.
In the UK, Pensana has begun construction of their US$195 million rare-earth processing plant which secured funding from the UK government's Automotive Transformation Fund. The plant will process ore from the Longonjo mine in Angola and other sources as they become available. The company are targeting production in late 2023, before ramping up to full capacity in 2024. Pensana aim to produce 12,500 metric tons of separated rare earths, including 4,500 tons of magnet metal rare earths.
Also under consideration for mining are sites such as Thor Lake in the Northwest Territories, and various locations in Vietnam. Additionally, in 2010, a large deposit of rare-earth minerals was discovered in Kvanefjeld in southern Greenland. Pre-feasibility drilling at this site has confirmed significant quantities of black lujavrite, which contains about 1% rare-earth oxides (REO). The European Union has urged Greenland to restrict Chinese development of rare-earth projects there, but as of early 2013, the government of Greenland has said that it has no plans to impose such restrictions. Many Danish politicians have expressed concerns that other nations, including China, could gain influence in thinly populated Greenland, given the number of foreign workers and investment that could come from Chinese companies in the near future because of the law passed December 2012.
In central Spain, Ciudad Real Province, the proposed rare-earth mining project 'Matamulas' may provide, according to its developers, up to 2,100 Tn/year (33% of the annual UE demand). However, this project has been suspended by regional authorities due to social and environmental concerns.
Adding to potential mine sites, ASX listed Peak Resources announced in February 2012, that their Tanzanian-based Ngualla project contained not only the 6th largest deposit by tonnage outside of China but also the highest grade of rare-earth elements of the 6.
North Korea has been reported to have exported rare-earth ore to China, about US$1.88 million worth during May and June 2014.
In May 2012, researchers from two universities in Japan announced that they had discovered rare earths in Ehime Prefecture, Japan.
On 12 January 2023, Swedish state-owned mining company LKAB announced that it had discovered a deposit of over 1 million tonnes of rare earths in the country's Kiruna area, which would make it the largest such deposit in Europe.
China processes about 90% of the world's REEs and 60% of the world's lithium. As a result, the European Union imports practically all of its rare earth elements from China. The EU Critical Raw Materials Act of 2023 has set in action the required policy adjustments for Europe to start producing two-thirds of the lithium-ion batteries required for electric vehicles and energy storage. In 2024, an EU backed lithium mining project created large scale protests in Serbia.
In 2024 American Rare Earths Inc. disclosed that its reserves near Wheatland Wyoming totaled 2.34 billion metric tons, possibly the world's largest and larger than a separate 1.2 million metric ton deposit in northeastern Wyoming.
In June 2024, Rare Earths Norway found a rare-earth oxide deposit of 8.8 million metric tons in Telemark, Norway, making it Europe's largest known rare-earth element deposit. The mining firm predicted that it would finish developing the first stage of mining in 2030.
Malaysian refining plans.
In early 2011, Australian mining company Lynas was reported to be "hurrying to finish" a US$230 million rare-earth refinery on the eastern coast of Peninsular Malaysia's industrial port of Kuantan. The plant would refine ore — lanthanides concentrate from the Mount Weld mine in Australia. The ore would be trucked to Fremantle and transported by container ship to Kuantan. Within two years, Lynas was said to expect the refinery to be able to meet nearly a third of the world's demand for rare-earth materials, not counting China. The Kuantan development brought renewed attention to the Malaysian town of Bukit Merah in Perak, where a rare-earth mine operated by a Mitsubishi Chemical subsidiary, Asian Rare Earth, closed in 1994 and left continuing environmental and health concerns. In mid-2011, after protests, Malaysian government restrictions on the Lynas plant were announced. At that time, citing subscription-only "Dow Jones Newswire" reports, a "Barrons" report said the Lynas investment was $730 million, and the projected share of the global market it would fill put at "about a sixth." An independent review initiated by the Malaysian Government, and conducted by the International Atomic Energy Agency (IAEA) in 2011 to address concerns of radioactive hazards, found no non-compliance with international radiation safety standards.
However, the Malaysian authorities confirmed that as of October 2011, Lynas was not given any permit to import any rare-earth ore into Malaysia. On February 2, 2012, the Malaysian AELB (Atomic Energy Licensing Board) recommended that Lynas be issued a temporary operating license subject to meeting a number of conditions. On 2 September 2014, Lynas was issued a 2-year full operating stage license by the AELB.
Other sources.
Mine tailings.
Significant quantities of rare-earth oxides are found in tailings accumulated from 50 years of uranium ore, shale, and loparite mining at Sillamäe, Estonia. Due to the rising prices of rare earths, extraction of these oxides has become economically viable. The country currently exports around 3,000 tonnes per year, representing around 2% of world production. Similar resources are suspected in the western United States, where gold rush-era mines are believed to have discarded large amounts of rare earths, because they had no value at the time.
Ocean mining.
In January 2013 a Japanese deep-sea research vessel obtained seven deep-sea mud core samples from the Pacific Ocean seafloor at 5,600 to 5,800 meters depth, approximately south of the island of Minami-Tori-Shima. The research team found a mud layer 2 to 4 meters beneath the seabed with concentrations of up to 0.66% rare-earth oxides. A potential deposit might compare in grade with the ion-absorption-type deposits in southern China that provide the bulk of Chinese REO mine production, which grade in the range of 0.05% to 0.5% REO.
Waste and recycling.
Another recently developed source of rare earths is electronic waste and other wastes that have significant rare-earth components. Advances in recycling technology have made the extraction of rare earths from these materials less expensive. Recycling plants operate in Japan, where an estimated 300,000 tons of rare earths are found in unused electronics. In France, the Rhodia group is setting up two factories, in La Rochelle and Saint-Fons, that will produce 200 tons of rare earths a year from used fluorescent lamps, magnets, and batteries. Coal and coal by-products, such as ash and sludge, are a potential source of critical elements including rare-earth elements (REE) with estimated amounts in the range of 50 million metric tons.
Methods.
One study mixed fly ash with carbon black and then sent a 1-second current pulse through the mixture, heating it to . The fly ash contains microscopic bits of glass that encapsulate the metals. The heat shatters the glass, exposing the rare earths. Flash heating also converts phosphates into oxides, which are more soluble and extractable. Using hydrochloric acid at concentrations less than 1% of conventional methods, the process extracted twice as much material.
Properties.
According to chemistry professor Andrea Sella, rare-earth elements differ from other elements, in that when looked at analytically, they are virtually inseparable, having almost the same chemical properties. However, in terms of their electronic and magnetic properties, each one occupies a unique technological niche that nothing else can. For example, "the rare-earth elements praseodymium (Pr) and neodymium (Nd) can both be embedded inside glass and they completely cut out the glare from the flame when one is doing glass-blowing."
Uses.
Global REE consumption, 2015
<templatestyles src="Legend/styles.css" /> Catalysts, 24%
(24%)<templatestyles src="Legend/styles.css" /> Magnets, 23% (23%)<templatestyles src="Legend/styles.css" /> Polishing, 12% (12%)<templatestyles src="Legend/styles.css" /> "other", 9% (9%)<templatestyles src="Legend/styles.css" /> Metallurgy, 8% (8%)<templatestyles src="Legend/styles.css" /> Batteries, 8% (8%)<templatestyles src="Legend/styles.css" /> Glass, 7% (7%)<templatestyles src="Legend/styles.css" /> Ceramics, 6% (6%)<templatestyles src="Legend/styles.css" /> Phosphors and pigments, 3% (3%)
US consumption of REE, 2018
<templatestyles src="Legend/styles.css" /> Catalysts, 60% (60%)<templatestyles src="Legend/styles.css" /> Ceramics and glass, 15% (15%)<templatestyles src="Legend/styles.css" /> Polishing, 10% (10%)<templatestyles src="Legend/styles.css" /> "other", 5% (5%)<templatestyles src="Legend/styles.css" /> Metallurgy, 10% (10%)
The uses, applications, and demand for rare-earth elements have expanded over the years. Globally, most REEs are used for catalysts and magnets. In the US, more than half of REEs are used for catalysts; ceramics, glass, and polishing are also main uses.
Other important uses of rare-earth elements are applicable to the production of high-performance magnets, alloys, glasses, and electronics. Ce and La are important as catalysts, and are used for petroleum refining and as diesel additives. Nd is important in magnet production in traditional and low-carbon technologies. Rare-earth elements in this category are used in the electric motors of hybrid and electric vehicles, generators in some wind turbines, hard disc drives, portable electronics, microphones, and speakers.
Ce, La, and Nd are important in alloy making, and in the production of fuel cells and nickel-metal hydride batteries. Ce, Ga, and Nd are important in electronics and are used in the production of LCD and plasma screens, fiber optics, and lasers, and in medical imaging. Additional uses for rare-earth elements are as tracers in medical applications, fertilizers, and in water treatment.
REEs have been used in agriculture to increase plant growth, productivity, and stress resistance seemingly without negative effects for human and animal consumption. REEs are used in agriculture through REE-enriched fertilizers which is a widely used practice in China. In addition, REEs are feed additives for livestock which has resulted in increased production such as larger animals and a higher production of eggs and dairy products. However, this practice has resulted in REE bioaccumulation within livestock and has impacted vegetation and algae growth in these agricultural areas. Additionally while no ill effects have been observed at current low concentrations the effects over the long term and with accumulation over time are unknown prompting some calls for more research into their possible effects.
Environmental considerations.
REEs are naturally found in very low concentrations in the environment. Mines are often in countries where environmental and social standards are very low, leading to human rights violations, deforestation, and contamination of land and water. Generally, it is estimated that extracting 1 tonne of rare earth element creates around 2,000 tonnes of waste, partly toxic, including 1 ton of radioactive waste. The largest mining site of REEs, Bayan Obo in China produced more than 70,000 tons of radioactive waste, that contaminated ground water.
Near mining and industrial sites, the concentrations of REEs can rise to many times the normal background levels. Once in the environment, REEs can leach into the soil where their transport is determined by numerous factors such as erosion, weathering, pH, precipitation, groundwater, etc. Acting much like metals, they can speciate depending on the soil condition being either motile or adsorbed to soil particles. Depending on their bio-availability, REEs can be absorbed into plants and later consumed by humans and animals. The mining of REEs, use of REE-enriched fertilizers, and the production of phosphorus fertilizers all contribute to REE contamination. Furthermore, strong acids are used during the extraction process of REEs, which can then leach out into the environment and be transported through water bodies and result in the acidification of aquatic environments. Another additive of REE mining that contributes to REE environmental contamination is cerium oxide (CeO2), which is produced during the combustion of diesel and released as exhaust, contributing heavily to soil and water contamination.
Mining, refining, and recycling of rare earths have serious environmental consequences if not properly managed. Low-level radioactive tailings resulting from the occurrence of thorium and uranium in rare-earth ores present a potential hazard and improper handling of these substances can result in extensive environmental damage. In May 2010, China announced a major, five-month crackdown on illegal mining in order to protect the environment and its resources. This campaign is expected to be concentrated in the South, where mines – commonly small, rural, and illegal operations – are particularly prone to releasing toxic waste into the general water supply. However, even the major operation in Baotou, in Inner Mongolia, where much of the world's rare-earth supply is refined, has caused major environmental damage. China's Ministry of Industry and Information Technology estimated that cleanup costs in Jiangxi province at $5.5 billion.
It is, however, possible to filter out and recover any rare-earth elements that flow out with the wastewater from mining facilities. However, such filtering and recovery equipment may not always be present on the outlets carrying the wastewater.
Recycling and reusing REEs.
Potential methods.
The rare-earth elements (REEs) are vital to modern technologies and society and are amongst the most critical elements. Despite this, typically only around 1% of REEs are recycled from end-products, with the rest deporting to waste and being removed from the materials cycle. Recycling and reusing REEs play an important role in high technology fields and manufacturing environmentally friendly products all around the world.
REE recycling and reuse have been increasingly focused on in recent years. The main concerns include environmental pollution during REE recycling and increasing recycling efficiency. Literature published in 2004 suggests that, along with previously established pollution mitigation, a more circular supply chain would help mitigate some of the pollution at the extraction point. This means recycling and reusing REEs that are already in use or reaching the end of their life cycle. A study published in 2014 suggests a method to recycle REEs from waste nickel-metal hydride batteries, demonstrating a recovery rate of 95.16%. Rare-earth elements could also be recovered from industrial wastes with practical potential to reduce environmental and health impacts from mining, waste generation, and imports if known and experimental processes are scaled up. A study suggests that "fulfillment of the circular economy approach could reduce up to 200 times the impact in the climate change category and up to 70 times the cost due to the REE mining." In most of the reported studies reviewed by a scientific review, "secondary waste is subjected to chemical and or bioleaching followed by solvent extraction processes for clean separation of REEs."
Currently, people take two essential resources into consideration for the secure supply of REEs: one is to extract REEs from primary resources like mines harboring REE-bearing ores, regolith-hosted clay deposits, ocean bed sediments, coal fly ash, etc. A work developed a green system for recovery of REEs from coal fly ash by using citrate and oxalate who are strong organic ligand and capable of complexing or precipItating with REE. The other one is from secondary resources such as electronic, industrial waste and municipal waste. E-waste contains a significant concentration of REEs, and thus is the primary option for REE recycling now. According to a study, approximately 50 million metric tons of electronic waste are dumped in landfills worldwide each year. Despite the fact that e-waste contains a significant amount of rare-earth elements (REE), only 12.5% of e-waste is currently being recycled for all metals.
Challenges.
For now, there are some obstacles during REE recycling and reuse. One big challenge is REE separation chemistry. Specifically, the process of isolating and refining individual rare earth elements (REE) presents a difficulty due to their similar chemical properties. In order to reduce the environmental pollution released during REE isolation and also diversify their sources, there is a clear necessity for the development of novel separation technologies that can lower the cost of large-scale REE separation and recycling. In this condition, the Critical Materials Institute (CMI) under the Department of Energy has devised a technique that involves utilizing Gluconobacter bacteria to metabolize sugars, producing acids that can dissolve and separate rare-earth elements (REE) from shredded electronic waste.
Impact of REE contamination.
On vegetation.
The mining of REEs has caused the contamination of soil and water around production areas, which has impacted vegetation in these areas by decreasing chlorophyll production, which affects photosynthesis and inhibits the growth of the plants. However, the impact of REE contamination on vegetation is dependent on the plants present in the contaminated environment: not all plants retain and absorb REEs. Also, the ability of the vegetation to intake the REE is dependent on the type of REE present in the soil, hence there are a multitude of factors that influence this process. Agricultural plants are the main type of vegetation affected by REE contamination in the environment, the two plants with a higher chance of absorbing and storing REEs being apples and beets. Furthermore, there is a possibility that REEs can leach out into aquatic environments and be absorbed by aquatic vegetation, which can then bio-accumulate and potentially enter the human food chain if livestock or humans choose to eat the vegetation. An example of this situation was the case of the water hyacinth ("Eichhornia crassipes)" in China, where the water was contaminated due to a REE-enriched fertilizer being used in a nearby agricultural area. The aquatic environment became contaminated with cerium and resulted in the water hyacinth becoming three times more concentrated in cerium than its surrounding water.
On human health.
REEs are a large group with many different properties and levels in the environment. Because of this, and limited research, it has been difficult to determine safe levels of exposure for humans. A number of studies have focused on risk assessment based on routes of exposure and divergence from background levels related to nearby agriculture, mining, and industry. It has been demonstrated that numerous REEs have toxic properties and are present in the environment or in work places. Exposure to these can lead to a wide range of negative health outcomes such as cancer, respiratory issues, dental loss, and even death. However REEs are numerous and present in many different forms and at different levels of toxicity, making it difficult to give blanket warnings on cancer risk and toxicity as some of these are harmless while others pose a risk.
What toxicity is shown appears to be at very high levels of exposure through ingestion of contaminated food and water, through inhalation of dust/smoke particles either as an occupational hazard, or due to proximity to contaminated sites such as mines and cities. Therefore, the main issues that these residents would face is bioaccumulation of REEs and the impact on their respiratory system but overall, there can be other possible short-term and long-term health effects. It was found that people living near mines in China had many times the levels of REEs in their blood, urine, bone, and hair compared to controls far from mining sites. This higher level was related to the high levels of REEs present in the vegetables they cultivated, the soil, and the water from the wells, indicating that the high levels were caused by the nearby mine. While REE levels varied between men and women, the group most at risk were children because REEs can impact the neurological development of children, affecting their IQ and potentially causing memory loss.
The rare-earth mining and smelting process can release airborne fluoride which will associate with total suspended particles (TSP) to form aerosols that can enter human respiratory systems and cause damage and respiratory diseases. Research from Baotou, China shows that the fluoride concentration in the air near REE mines is higher than the limit value from WHO, which can affect the surrounding environment and become a risk to those who live or work nearby.
Residents blamed a rare-earth refinery at Bukit Merah for birth defects and eight leukemia cases within five years in a community of 11,000 after many years with no leukemia cases. Seven of the leukemia victims died. Osamu Shimizu, a director of Asian Rare Earth, said "the company might have sold a few bags of calcium phosphate fertilizer on a trial basis as it sought to market byproducts; calcium phosphate is not radioactive or dangerous" in reply to a former resident of Bukit Merah who said that "The cows that ate the grass [grown with the fertilizer] all died." Malaysia's Supreme Court ruled on 23 December 1993 that there was no evidence that the local chemical joint venture Asian Rare Earth was contaminating the local environment.
On animal health.
Experiments exposing rats to various cerium compounds have found accumulation primarily in the lungs and liver. This resulted in various negative health outcomes associated with those organs. REEs have been added to feed in livestock to increase their body mass and increase milk production. They are most commonly used to increase the body mass of pigs, and it was discovered that REEs increase the digestibility and nutrient use of pigs' digestive systems. Studies point to a dose-response when considering toxicity versus positive effects. While small doses from the environment or with proper administration seem to have no ill effects, larger doses have been shown to have negative effects specifically in the organs where they accumulate. The process of mining REEs in China has resulted in soil and water contamination in certain areas, which when transported into aquatic bodies could potentially bio-accumulate within aquatic biota. Furthermore, in some cases, animals that live in REE-contaminated areas have been diagnosed with organ or system problems. REEs have been used in freshwater fish farming because it protects the fish from possible diseases. One main reason why they have been avidly used in animal livestock feeding is that they have had better results than inorganic livestock feed enhancers.
Remediation after pollution.
After the 1982 Bukit Merah radioactive pollution, the mine in Malaysia has been the focus of a US$100 million cleanup that is proceeding in 2011. After having accomplished the hilltop entombment of 11,000 truckloads of radioactively contaminated material, the project is expected to entail in summer, 2011, the removal of "more than 80,000 steel barrels of radioactive waste to the hilltop repository."
In May 2011, after the Fukushima nuclear disaster, widespread protests took place in Kuantan over the Lynas refinery and radioactive waste from it. The ore to be processed has very low levels of thorium, and Lynas founder and chief executive Nicholas Curtis said "There is absolutely no risk to public health." T. Jayabalan, a doctor who says he has been monitoring and treating patients affected by the Mitsubishi plant, "is wary of Lynas's assurances. The argument that low levels of thorium in the ore make it safer doesn't make sense, he says, because radiation exposure is cumulative." Construction of the facility has been halted until an independent United Nations IAEA panel investigation is completed, which is expected by the end of June 2011. New restrictions were announced by the Malaysian government in late June.
An IAEA panel investigation was completed and no construction has been halted. Lynas is on budget and on schedule to start producing in 2011. The IAEA concluded in a report issued in June 2011 that it did not find any instance of "any non-compliance with international radiation safety standards" in the project.
If the proper safety standards are followed, REE mining is relatively low impact. Molycorp (before going bankrupt) often exceeded environmental regulations to improve its public image.
In Greenland, there is a significant dispute on whether to start a new rare-earth mine in Kvanefjeld due to environmental concerns.
Geopolitical considerations.
China has officially cited resource depletion and environmental concerns as the reasons for a nationwide crackdown on its rare-earth mineral production sector. However, non-environmental motives have also been imputed to China's rare-earth policy. According to "The Economist", "Slashing their exports of rare-earth metals ... is all about moving Chinese manufacturers up the supply chain, so they can sell valuable finished goods to the world rather than lowly raw materials." Furthermore, China currently has an effective monopoly on the world's REE Value Chain. (All of the refineries and processing plants that transform the raw ore into valuable elements.) In the words of Deng Xiaoping, a Chinese politician from the late 1970s to the late 1980s, "The Middle East has oil; we have rare earths ... it is of extremely important strategic significance; we must be sure to handle the rare earth issue properly and make the fullest use of our country's advantage in rare-earth resources."
One possible example of market control is the division of General Motors that deals with miniaturized magnet research, which shut down its US office and moved its entire staff to China in 2006 (China's export quota only applies to the metal but not products made from these metals such as magnets).
It was reported, but officially denied, that China instituted an export ban on shipments of rare-earth oxides (but not alloys) to Japan on 22 September 2010, in response to the detainment of a Chinese fishing boat captain by the Japanese Coast Guard. On September 2, 2010, a few days before the fishing boat incident, "The Economist" reported that "China ... in July announced the latest in a series of annual export reductions, this time by 40% to precisely 30,258 tonnes."
The United States Department of Energy in its 2010 Critical Materials Strategy report identified dysprosium as the element that was most critical in terms of import reliance.
A 2011 report "China's Rare-Earth Industry", issued by the US Geological Survey and US Department of the Interior, outlines industry trends within China and examines national policies that may guide the future of the country's production. The report notes that China's lead in the production of rare-earth minerals has accelerated over the past two decades. In 1990, China accounted for only 27% of such minerals. In 2009, world production was 132,000 metric tons; China produced 129,000 of those tons. According to the report, recent patterns suggest that China will slow the export of such materials to the world: "Owing to the increase in domestic demand, the Government has gradually reduced the export quota during the past several years." In 2006, China allowed 47 domestic rare-earth producers and traders and 12 Sino-foreign rare-earth producers to export. Controls have since tightened annually; by 2011, only 22 domestic rare-earth producers and traders and 9 Sino-foreign rare-earth producers were authorized. The government's future policies will likely keep in place strict controls: "According to China's draft rare-earth development plan, annual rare-earth production may be limited to between 130,000 and 140,000 [metric tons] during the period from 2009 to 2015. The export quota for rare-earth products may be about 35,000 [metric tons] and the Government may allow 20 domestic rare-earth producers and traders to export rare earths."
The United States Geological Survey is actively surveying southern Afghanistan for rare-earth deposits under the protection of United States military forces. Since 2009 the USGS has conducted remote sensing surveys as well as fieldwork to verify Soviet claims that volcanic rocks containing rare-earth metals exist in Helmand Province near the village of Khanashin. The USGS study team has located a sizable area of rocks in the center of an extinct volcano containing light rare-earth elements including cerium and neodymium. It has mapped 1.3 million metric tons of desirable rock, or about ten years of supply at current demand levels. The Pentagon has estimated its value at about $7.4 billion.
It has been argued that the geopolitical importance of rare earths has been exaggerated in the literature on the geopolitics of renewable energy, underestimating the power of economic incentives for expanded production. This especially concerns neodymium. Due to its role in permanent magnets used for wind turbines, it has been argued that neodymium will be one of the main objects of geopolitical competition in a world running on renewable energy. But this perspective has been criticized for failing to recognize that most wind turbines have gears and do not use permanent magnets.
In popular culture.
The plot of Eric Ambler's now-classic 1967 international crime-thriller "Dirty Story" (aka "This Gun for Hire", but not to be confused with the movie "This Gun for Hire" (1942)) features a struggle between two rival mining cartels to control a plot of land in a fictional African country, which contains rich minable rare-earth ore deposits.
References.
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"math_id": 0,
"text": "[\\text{REE}_i]_n = \\frac{[\\text{REE}_i]_\\text{sam}}{[\\text{REE}_i]_\\text{std}}"
},
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"math_id": 1,
"text": "{[\\text{REE}_i]_\\text{sam}}"
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"text": "{[\\text{REE}_i]_\\text{ref}}"
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"math_id": 3,
"text": "\\frac{\\text{REE}_i}{\\text{REE}_i^*} = \\frac{[\\text{REE}_i]_n \\times 2}{[\\text{REE}_{i-1}]_n + [\\text{REE}_{i+1}]_n}"
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"text": "[\\text{REE}_i]_n"
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"text": "[\\text{REE}_{i-1}]_n"
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"text": "[\\text{REE}_{i+1}]_n"
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https://en.wikipedia.org/wiki?curid=145440
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14544014
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Phenylalanine N-acetyltransferase
|
In enzymology, a phenylalanine N-acetyltransferase (EC 2.3.1.53) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + L-phenylalanine formula_0 CoA + N-acetyl-L-phenylalanine
Thus, the two substrates of this enzyme are acetyl-CoA and L-phenylalanine, whereas its two products are CoA and N-acetyl-L-phenylalanine.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:L-phenylalanine N-acetyltransferase. This enzyme is also called acetyl-CoA-L-phenylalanine alpha-N-acetyltransferase. This enzyme participates in phenylalanine metabolism.
References.
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https://en.wikipedia.org/wiki?curid=14544014
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14544035
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Phloroisovalerophenone synthase
|
In enzymology, a phloroisovalerophenone synthase (EC 2.3.1.156) is an enzyme that catalyzes the chemical reaction
isovaleryl-CoA + 3 malonyl-CoA formula_0 4 CoASH + 3 CO2 + 3-methyl-1-(2,4,6-trihydroxyphenyl)butan-1-one
Thus, the two substrates of this enzyme are isovaleryl-CoA and malonyl-CoA, whereas its 3 products are CoASH, CO2, and 3-methyl-1-(2,4,6-trihydroxyphenyl)butan-1-one.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is isovaleryl-CoA:malonyl-CoA acyltransferase. Other names in common use include valerophenone synthase, and 3-methyl-1-(trihydroxyphenyl)butan-1-one synthase.
References.
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[
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https://en.wikipedia.org/wiki?curid=14544035
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14544047
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Phosphate acetyltransferase
|
In enzymology, a phosphate acetyltransferase (EC 2.3.1.8) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + phosphate formula_0 CoA + acetyl phosphate
The substrates of this enzyme are acetyl-CoA and phosphate, whereas its two products are CoA and acetyl phosphate.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:phosphate acetyltransferase. Other names in common use include phosphotransacetylase, phosphoacylase, and PTA. This enzyme participates in 3 metabolic pathways: taurine and hypotaurine metabolism, pyruvate metabolism, and propanoate metabolism.
Structural studies.
As of late 2007, 7 structures have been solved for this class of enzymes, with PDB accession codes 1QZT, 1R5J, 1TD9, 1VMI, 1XCO, 2AF3, and 2AF4.
References.
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[
{
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"text": "\\rightleftharpoons"
}
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https://en.wikipedia.org/wiki?curid=14544047
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14544069
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Phosphate butyryltransferase
|
In enzymology, a phosphate butyryltransferase (EC 2.3.1.19) is an enzyme that catalyzes the chemical reaction
butanoyl-CoA + phosphate formula_0 CoA + butanoyl phosphate
Thus, the two substrates of this enzyme are butanoyl-CoA and phosphate, whereas its two products are CoA and butanoyl phosphate.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is butanoyl-CoA:phosphate butanoyltransferase. This enzyme is also called phosphotransbutyrylase. This enzyme participates in butanoate metabolism.
References.
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
}
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https://en.wikipedia.org/wiki?curid=14544069
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14544099
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Phosphatidylcholine—dolichol O-acyltransferase
|
In enzymology, a phosphatidylcholine---dolichol O-acyltransferase (EC 2.3.1.83) is an enzyme that catalyzes the chemical reaction
3-sn-phosphatidylcholine + dolichol formula_0 1-acyl-sn-glycero-3-phosphocholine + acyldolichol
Thus, the two substrates of this enzyme are 3-sn-phosphatidylcholine and dolichol, whereas its two products are 1-acyl-sn-glycero-3-phosphocholine and acyldolichol.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is 3-sn-phosphatidylcholine:dolichol O-acyltransferase.
References.
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14544099
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14544120
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Phosphatidylcholine—retinol O-acyltransferase
|
In enzymology, a phosphatidylcholine---retinol O-acyltransferase (EC 2.3.1.135) is an enzyme that catalyzes the chemical reaction
phosphatidylcholine + retinol---[cellular-retinol-binding-protein] formula_0 2-acylglycerophosphocholine + retinyl-ester---[cellular-retinol-binding-protein]
Thus, the two substrates of this enzyme are phosphatidylcholine and retinol---[cellular-retinol-binding-protein], whereas its two products are 2-acylglycerophosphocholine and retinyl-ester---[cellular-retinol-binding-protein].
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is phosphatidylcholine:retinol---[cellular-retinol-binding-protein] O-acyltransferase. Other names in common use include lecithin---retinol acyltransferase, phosphatidylcholine:retinol-(cellular-retinol-binding-protein), and O-acyltransferase.
References.
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[
{
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"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14544120
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14544137
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Phosphatidylcholine—sterol O-acyltransferase
|
In enzymology, a phosphatidylcholine---sterol O-acyltransferase (EC 2.3.1.43) is an enzyme that catalyzes the chemical reaction
phosphatidylcholine + a sterol formula_0 1-acylglycerophosphocholine + a sterol ester
Thus, the two substrates of this enzyme are phosphatidylcholine and sterol, whereas its two products are 1-acylglycerophosphocholine and sterol ester.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is phosphatidylcholine:sterol O-acyltransferase. Other names in common use include lecithin---cholesterol acyltransferase, phospholipid---cholesterol acyltransferase, LCAT (lecithin-cholesterol acyltransferase), lecithin:cholesterol acyltransferase, and lysolecithin acyltransferase. This enzyme participates in glycerophospholipid metabolism.
References.
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14544137
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14544174
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Pinosylvin synthase
|
In enzymology, a pinosylvin synthase (EC 2.3.1.146) is an enzyme that catalyzes the chemical reaction
3 malonyl-CoA + cinnamoyl-CoA formula_0 4 CoA + pinosylvin + 4 CO2
Thus, the two substrates of this enzyme are malonyl-CoA and cinnamoyl-CoA, whereas its 3 products are CoA, pinosylvin, and CO2.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is malonyl-CoA:cinnamoyl-CoA malonyltransferase (cyclizing). Other names in common use include stilbene synthase, and pine stilbene synthase. This enzyme participates in phenylpropanoid biosynthesis.
References.
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[
{
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"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14544174
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14544189
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Piperidine N-piperoyltransferase
|
Enzyme
In enzymology, a piperidine N-piperoyltransferase (EC 2.3.1.145) is an enzyme that catalyzes the chemical reaction
(E,E)-piperoyl-CoA + piperidine formula_0 CoA + N-[(E,E)-piperoyl]-piperidine
Thus, the two substrates of this enzyme are (E,E)-piperoyl-CoA and piperidine, whereas its two products are CoA and N-[(E,E)-piperoyl]-piperidine.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is (E,E)-piperoyl-CoA:piperidine N-piperoyltransferase. Other names in common use include piperidine piperoyltransferase, and piperoyl-CoA:piperidine N-piperoyltransferase.
References.
<templatestyles src="Reflist/styles.css" />
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14544189
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14544210
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Plasmalogen synthase
|
Class of enzymes
In enzymology, a plasmalogen synthase (EC 2.3.1.25) is an enzyme that catalyzes the chemical reaction
acyl-CoA + 1-O-alk-1-enyl-glycero-3-phosphocholine formula_0 CoA + plasmenylcholine
Thus, the two substrates of this enzyme are acyl-CoA and 1-O-alk-1-enyl-glycero-3-phosphocholine, whereas its two products are CoA and plasmenylcholine.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acyl-CoA:1-O-alk-1-enyl-glycero-3-phosphocholine 2-O-acyltransferase. Other names in common use include lysoplasmenylcholine acyltransferase, O-1-alkenylglycero-3-phosphorylcholine acyltransferase, and 1-alkenyl-glycero-3-phosphorylcholine:acyl-CoA acyltransferase. This enzyme participates in ether lipid metabolism.
References.
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
}
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https://en.wikipedia.org/wiki?curid=14544210
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14544231
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Platelet-activating factor acetyltransferase
|
Class of enzymes
In enzymology, a platelet-activating factor acetyltransferase (EC 2.3.1.149) is an enzyme that catalyzes the chemical reaction
1-alkyl-2-acetyl-sn-glycero-3-phosphocholine + 1-organyl-2-lyso-sn-glycero-3-phospholipid formula_0 1-organyl-2-lyso-sn-glycero-3-phosphocholine + 1-alkyl-2-acetyl-sn-glycero-3-phospholipid
Thus, the two substrates of this enzyme are 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine and 1-organyl-2-lyso-sn-glycero-3-phospholipid, whereas its two products are 1-organyl-2-lyso-sn-glycero-3-phosphocholine and 1-alkyl-2-acetyl-sn-glycero-3-phospholipid.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is 1-alkyl-2-acyl-sn-glycero-3-phosphocholine:1-organyl-2-lyso-sn-glyce ro-3-phospholipid acetyltransferase. This enzyme is also called PAF acetyltransferase.
References.
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[
{
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"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14544231
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14544255
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Polysialic-acid O-acetyltransferase
|
In enzymology, a polysialic-acid O-acetyltransferase (EC 2.3.1.136) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + an alpha-2,8-linked polymer of sialic acid formula_0 CoA + polysialic acid acetylated on O-7 or O-9
Thus, the two substrates of this enzyme are acetyl-CoA and alpha-2,8-linked polymer of sialic acid, whereas its 3 products are CoA, polysialic acid acetylated on O-7, and polysialic acid acetylated on O-9.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:polysialic-acid O-acetyltransferase. Other names in common use include lecithin:retinol acyltransferase, lecithin-retinol acyltransferase, retinyl ester synthase, LRAT, and lecithin retinol acyl transferase.
References.
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14544255
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14544273
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Propanoyl-CoA C-acyltransferase
|
In enzymology, a propanoyl-CoA C-acyltransferase (EC 2.3.1.176) is an enzyme that catalyzes the chemical reaction
3alpha,7alpha,12alpha-trihydroxy-5beta-cholanoyl-CoA + propanoyl-CoA formula_0 CoA + 3alpha,7alpha,12alpha-trihydroxy-24-oxo-5beta-cholestanoyl-CoA
Thus, the two substrates of this enzyme are 3alpha,7alpha,12alpha-trihydroxy-5beta-cholanoyl-CoA and propanoyl-CoA, whereas its two products are CoA and 3alpha,7alpha,12alpha-trihydroxy-24-oxo-5beta-cholestanoyl-CoA.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is 3alpha,7alpha,12alpha-trihydroxy-5beta-cholanoyl-CoA:propanoyl-CoA C-acyltransferase. Other names in common use include peroxisomal thiolase 2, sterol carrier protein-, SCP, and PTE-2 (ambiguous). This enzyme participates in ppar signaling pathway.
Propanoyl-CoA C-acyltransferase belongs to the thiolase family of enzymes.
References.
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[
{
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"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14544273
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14544297
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Propionyl-CoA C2-trimethyltridecanoyltransferase
|
In enzymology, a propionyl-CoA C2-trimethyltridecanoyltransferase (EC 2.3.1.154) is an enzyme that catalyzes the chemical reaction
4,8,12-trimethyltridecanoyl-CoA + propanoyl-CoA formula_0 3-oxopristanoyl-CoA + CoA
Thus, the two substrates of this enzyme are 4,8,12-trimethyltridecanoyl-CoA and propanoyl-CoA, whereas its two products are 3-oxopristanoyl-CoA and CoA.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is 4,8,12-trimethyltridecanoyl-CoA:propanoyl-CoA C2-4,8,12-trimethyltridecanoyltransferase. Other names in common use include 3-oxopristanoyl-CoA hydrolase, 3-oxopristanoyl-CoA thiolase, peroxisome sterol carrier protein thiolase, sterol carrier protein, oxopristanoyl-CoA thiolase, peroxisomal 3-oxoacyl coenzyme A thiolase, SCPx, 4,8,12-trimethyltridecanoyl-CoA:propanoyl-CoA, and 2-C-4,8,12-trimethyltridecanoyltransferase.
References.
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[
{
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https://en.wikipedia.org/wiki?curid=14544297
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14544335
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Putrescine N-hydroxycinnamoyltransferase
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Class of enzymes
In enzymology, a putrescine N-hydroxycinnamoyltransferase (EC 2.3.1.138) is an enzyme that catalyzes the chemical reaction
caffeoyl-CoA + putrescine formula_0 CoA + N-caffeoylputrescine
Thus, the two substrates of this enzyme are caffeoyl-CoA and putrescine, whereas its two products are CoA and N-caffeoylputrescine.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is caffeoyl-CoA:putrescine N-(3,4-dihydroxycinnamoyl)transferase. Other names in common use include caffeoyl-CoA putrescine N-caffeoyl transferase, PHT, putrescine hydroxycinnamoyl transferase, hydroxycinnamoyl-CoA:putrescine hydroxycinnamoyltransferase, and putrescine hydroxycinnamoyltransferase.
References.
<templatestyles src="Reflist/styles.css" />
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
}
] |
https://en.wikipedia.org/wiki?curid=14544335
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14544345
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Quinate O-hydroxycinnamoyltransferase
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In enzymology, a quinate O-hydroxycinnamoyltransferase (EC 2.3.1.99) is an enzyme that catalyzes the chemical reaction
feruloyl-CoA + quinate formula_0 CoA + O-feruloylquinate
Thus, the two substrates of this enzyme are feruloyl-CoA and quinate, whereas its two products are CoA and O-feruloylquinate.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is feruloyl-CoA:quinate O-(hydroxycinnamoyl)transferase. This enzyme is also called hydroxycinnamoyl coenzyme A-quinate transferase. This enzyme participates in phenylpropanoid biosynthesis.
References.
<templatestyles src="Reflist/styles.css" />
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
}
] |
https://en.wikipedia.org/wiki?curid=14544345
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14544367
|
Retinol O-fatty-acyltransferase
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In enzymology, a retinol O-fatty-acyltransferase (EC 2.3.1.76) is an enzyme that catalyzes the chemical reaction
acyl-CoA + retinol formula_0 CoA + retinyl ester
Thus, the two substrates of this enzyme are acyl-CoA and retinol, whereas its two products are CoA and retinyl ester.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acyl-CoA:retinol O-acyltransferase. Other names in common use include retinol acyltransferase, and retinol fatty-acyltransferase. This enzyme participates in retinol metabolism.
References.
<templatestyles src="Reflist/styles.css" />
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
}
] |
https://en.wikipedia.org/wiki?curid=14544367
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14544389
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Ribosomal-protein-alanine N-acetyltransferase
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In enzymology, a ribosomal-protein-alanine N-acetyltransferase (EC 2.3.1.128) is an enzyme that catalyzes the chemical reaction
acetyl-CoA + ribosomal-protein L-alanine formula_0 CoA + ribosomal-protein N-acetyl-L-alanine
Thus, the two substrates of this enzyme are acetyl-CoA and ribosomal-protein L-alanine, whereas its two products are CoA and ribosomal-protein N-acetyl-L-alanine.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:ribosomal-protein-L-alanine N-acetyltransferase. This enzyme is also called ribosomal protein S18 acetyltransferase.
Structural studies.
As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes 2CNM, 2CNS, and 2CNT.
References.
<templatestyles src="Reflist/styles.css" />
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
}
] |
https://en.wikipedia.org/wiki?curid=14544389
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14544404
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Rosmarinate synthase
|
In enzymology, a rosmarinate synthase (EC 2.3.1.140) is an enzyme that catalyzes the chemical reaction
caffeoyl-CoA + 3-(3,4-dihydroxyphenyl)lactate formula_0 CoA + rosmarinate
Thus, the two substrates of this enzyme are caffeoyl-CoA and 3-(3,4-dihydroxyphenyl)lactate, whereas its two products are CoA and rosmarinate.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is caffeoyl-CoA:3-(3,4-dihydroxyphenyl)lactate 2'-O-caffeoyl-transferase. Other names in common use include rosmarinic acid synthase, caffeoyl-coenzyme A:3,4-dihydroxyphenyllactic acid, caffeoyltransferase, and 4-coumaroyl-CoA:4-hydroxyphenyllactic acid 4-coumaroyl transferase. This enzyme participates in tyrosine metabolism.
References.
<templatestyles src="Reflist/styles.css" />
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
}
] |
https://en.wikipedia.org/wiki?curid=14544404
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