Betaine—homocysteine S-methyltransferase


In enzymology, a betaine-homocysteine S-methyltransferase also known as betaine-homocysteine methyltransferase is a zinc metallo-enzyme that catalyzes the transfer of a methyl group from trimethylglycine and a hydrogen ion from homocysteine to produce dimethylglycine and methionine respectively:
BHMT belongs to the family of transferases, specifically those transferring one-carbon group methyltransferases. It participates in the metabolism of glycine, serine, threonine, and methionine.

Isozymes

In humans, there are two isozymes, BHMT and BHMT2, each encoded by a separate gene.

Tissue distribution

BHMT is expressed most predominantly in the liver and kidney.

Clinical significance

Mutations in the BHMT gene are known to exist in humans. Anomalies may influence the metabolism of homocysteine, which is implicated in disorders ranging from vascular disease, autism, and schizophrenia to neural tube birth defects such as spina bifida.