Betaine-homocysteine S-methyltransferase (BHMT)

Betaine-homocysteine S-methyltransferase is a zinc-dependent enzyme that catalyzes the transfer of a methyl group from betaine (trimethylglycine) to homocysteine, resulting in the formation of dimethylglycine and methionine. This reaction is crucial for maintaining normal levels of both methionine and homocysteine in the body—a key aspect of one-carbon metabolism. The enzyme is predominantly expressed in liver and kidney but also found at lower levels in other tissues such as the lens nucleus during development. Mutations or altered expression can disrupt homocysteine homeostasis, contributing to cardiovascular diseases, neural tube defects like spina bifida, autism spectrum disorders, and schizophrenia. Clinically relevant drugs include betaine as a substrate used therapeutically for certain metabolic conditions involving elevated homocysteinemia. The gene encoding this protein is BHMT; there are related isoforms such as BHMT2 with distinct but related functions.

Other names

betaine-homocysteine methyltransferasebetaine--homocysteine S-methyltransferase 1EC 2.1.1.5BHMT1

Catalyzes the transfer of a methyl group from betaine to homocysteine, producing dimethylglycine and methionine; drugs may act as substrates or inhibitors of this enzymatic reaction