reductase (warfarin-insensitive) RRM1 RRM2 RRM2B :Category:EC 1.17.5 Caffeine dehydrogenase :Category:EC 1.17.7 :Category:EC 1.17.99 :Category:EC 1.18 (act on iron–sulfur proteins as donors) :Category:EC 1.18.6 Nitrogenase :Category:EC 1.19 (act on reduced flavodoxin as donor) :Category:EC 1.19.6 Nitrogenase (flavodoxin) :Category:EC 1.20 (act on phosphorus or arsenic as donors) :Category:EC 1.20.1 :Category:EC 1.20.2 :Category:EC 1.20.4 Arsenate reductase (glutaredoxin) Glutaredoxin :Category:EC 1.20.9 :Category:EC 1.20.99 :Category:EC 1.21 (act on X-H and Y-H to form an X-Y bond) :Category:EC 1.21.1 Iodotyrosine deiodinase :Category:EC 1.21.3 Isopenicillin N synthase Tetrahydrocannabinolic acid synthase :Category:EC 1.21.4 :Category:EC 1.21.99 Thyroxine 5-deiodinase Iodothyronine deiodinase and :Category:EC 1.97 (other oxidoreductases) :Category:EC 1.97.1 Deiodinase :Category:Transferases (EC 2) (Transferase) Glutathione S-transferase :Category:EC 2.1 (transfer one-carbon groups, Methylase) :Category:EC 2.1.1 Catechol-O-methyl transferase DNA methyltransferase , , Histone methyltransferase , :Category:EC 2.1.3 Aspartate transcarbamoylase Ornithine transcarbamoylase :Category:EC 2.2 (transfer aldehyde or ketone groups) :Category:EC 2.2.1 Transketolase Transaldolase Acetolactate synthase 2-Succinyl-5-enolpyruvyl-6-hydroxy-3-cyclohexene-1-carboxylic-acid synthase :Category:EC 2.3 (acyltransferases) :Category:EC 2.3.1 Aminolevulinic acid synthase Choline acetyltransferase :Category:EC 2.3.2 Factor XIII Gamma glutamyl transpeptidase Transglutaminase :Category:EC 2.4 (glycosyltransferases) :Category:EC 2.4.2 Hypoxanthine-guanine phosphoribosyltransferase :Category:EC 2.5 :Category:EC 2.5.1 Thiaminase :Category:EC 2.5 (transfer alkyl or aryl groups, other than methyl groups) Flavin prenyltransferase :Category:EC 2.6 (transfer nitrogenous groups) :Category:EC 2.6.1 Alanine transaminase Aspartate transaminase :Category:EC 2.7 (transfer phosphorus-containing groups) :Category:EC 2.7.2 Butyrate kinase () :Category:EC 2.8 (transfer sulfur-containing groups) : Thiosulfate sulfurtransferase : 3-mercaptopyruvate sulfurtransferase : Thiosulfate—thiol sulfurtransferase : tRNA uracil 4-sulfurtransferase : Thiosulfate—dithiol sulfurtransferase : Biotin synthase : Cysteine desulfurase : Lipoyl synthase : Molybdenum cofactor sulfurtransferase : Thiazole synthase : Molybdopterin synthase sulfurtransferase : Molybdopterin synthase : tRNA-uridine 2-sulfurtransferase : tRNA-5-taurinomethyluridine 2-sulfurtransferase : tRNA-5-methyluridine(54) 2-sulfurtransferase :Category:EC 2.9 (transfer selenium-containing groups) : L-seryl-tRNA(Sec) selenium transferase : O-phospho-L-seryl-tRNA(Sec):L-selenocysteinyl-tRNA synthase :Category:Hydrolases (EC 3) (Hydrolase) Hydrolytic enzyme :Category:EC 3.1 (act on ester bonds) Nuclease Endonuclease Exonuclease :Category:EC 3.1.1 Acid hydrolase Phospholipase A () Acetylcholinesterase () Cholinesterase () Lipoprotein lipase () :Category:EC 3.1.2 Ubiquitin carboxy-terminal hydrolase L1 () :Category:EC 3.1.3 Phosphatase Alkaline phosphatase () Fructose bisphosphatase () :Category:EC 3.1.4 Phospholipase C () CGMP specific phosphodiesterase type 5 () Phospholipase D () :Category:EC 3.1.21 Restriction enzyme Type 1 () Restriction enzyme Type 2 () Restriction enzyme Type 3 () Restriction enzyme Type 4 (?) Deoxyribonuclease I () :Category:EC 3.1.26 RNase H () :Category:EC 3.1.27 Ribonuclease :Category:EC 3.2 (act on sugars - glycosylases) :Category:EC 3.2.1 Amylase () Sucrase () Chitinase () Lysozyme () Maltase () Lactase () Beta-galactosidase () Hyaluronidase () Function and clinical importance of some enzymes in category 3.2.1 Amylase