Betaine-homocysteine S-methyltransferase

In enzymology, a betaine-homocysteine S-methyltransferase is an enzyme that catalyzes the chemical reaction


 * trimethylammonioacetate + L-homocysteine $$\rightleftharpoons$$ dimethylglycine + L-methionine

Thus, the two substrates of this enzyme are trimethylammonioacetate and L-homocysteine, whereas its two products are dimethylglycine and L-methionine.

This enzyme belongs to the family of transferases, specifically those transferring one-carbon group methyltransferases. The systematic name of this enzyme class is trimethylammonioacetate:L-homocysteine S-methyltransferase. Other names in common use include betaine-homocysteine methyltransferase, and betaine-homocysteine transmethylase. This enzyme participates in the metabolism of glycine, serine, threonine and also methionine.

Structural studies
As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes, , and.