enzymes are usually composed of proteins.
enzymes are usually composed of which type of molecule?
proteins
"catalysis of a biochemical reaction at physiological temperatures. in biologically catalyzed reactions, the reactants are known as substrates, and the catalysts are naturally occurring macromolecular substances known as enzymes. enzymes possess specific binding sites for substrates, and are usually composed wholly or largely of protein, but rna that has catalytic activity (ribozyme) is often also regarded as enzymatic."br









































note: see the wikipedia .









































section::::molecular function.:catalytic activity.:aromatase activity.









































exact_synonym: "estrogen synthetase"br









































"catalysis of the reaction: r-h + reduced flavoprotein + o2 = r-oh + oxidized flavoprotein + h2o."









































bullet::::- see the wikipedia .









































section::::molecular function.:catalytic activity.:motor activity.
list of types of proteins
the m6a methyltransferases (n-6 adenine-specific dna methylase) (a-mtase) are enzymes that specifically methylate the amino group at the c-6 position of adenines in dna. they are found in the three existing types of bacterial restriction-modification systems (in type i system the a-mtase is the product of the hsdm gene, and in type iii it is the product of the mod gene). these enzymes are responsible for the methylation of specific dna sequences in order to prevent the host from digesting its own genome via its restriction enzymes. these methylases have the same sequence specificity as their corresponding restriction enzymes. these enzymes contain a conserved motif asp/asn-pro-pro-tyr/phe in their n-terminal section, this conserved region could be involved in substrate binding or in the catalytic activity. the structure of n6-mtase taqi (m.taqi) has been resolved to 2.4 a. the molecule folds into 2 domains, an n-terminal catalytic domain, which contains the catalytic and cofactor binding sites, and comprises a central 9-stranded beta-sheet, surrounded by 5 helices; and a c-terminal dna recognition domain, which is formed by 4 small beta-sheets and 8 alpha-helices. the n- and c-terminal domains form a cleft that accommodates the dna substrate. a classification of n-mtases has been proposed, based on conserved motif (cm) arrangements. according to this classification, n6-mtases that have a dppy motif (cm ii) occurring after the fxgxg motif (cm i) are designated d12 class n6-adenine mtases. the type i restriction and modification system is composed of three polypeptides r, m and s. the m (hsdm) and s subunits together form a methyltransferase that methylates two adenine residues in complementary strands of a bipartite dna recognition sequence. in the presence of the r subunit, the complex can also act as an endonuclease, binding to the same target sequence but cutting the dna some distance from this site. whether the dna is cut or modified depends on the methylation state of the target sequence. when the target site is unmodified, the dna is cut. when the target site is hemimethylated, the complex acts as a maintenance methyltransferase, modifying the dna so that both strands become methylated. hsdm contains an alpha-helical domain at the n-terminus, the hsdm n-terminal domain.
dna methyltransferase