Caffeate O-methyltransferase

In enzymology, a caffeate O-methyltransferase (EC 2.1.1.68) is an enzyme that catalyzes the chemical reaction

S-adenosyl-L-methionine + 3,4-dihydroxy-trans-cinnamate $\rightleftharpoons$ S-adenosyl-L-homocysteine + 3-methoxy-4-hydroxy-trans-cinnamate

Thus, the two substrates of this enzyme are S-adenosyl methionine and 3,4-dihydroxy-trans-cinnamate (caffeic acid), whereas its two products are S-adenosylhomocysteine and 3-methoxy-4-hydroxy-trans-cinnamate (ferulic acid).

This enzyme belongs to the family of transferases, specifically those transferring one-carbon group methyltransferases. The systematic name of this enzyme class is S-adenosyl-L-methionine:3,4-dihydroxy-trans-cinnamate 3-O-methyltransferase. Other names in common use include caffeate methyltransferase, caffeate 3-O-methyltransferase, and S-adenosyl-L-methionine:caffeic acid-O-methyltransferase. This enzyme participates in phenylpropanoid biosynthesis.

Structural studies

As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes 1KYW and 1KYZ.