Betaine—homocysteine S-methyltransferase on:
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This enzyme belongs to the family of transferases, specifically those transferring one-carbon group methyltransferases. This enzyme participates in the metabolism of glycine,
enzymology
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...
, a betaine-homocysteine S-methyltransferase also known as betaine-homocysteine methyltransferase (BHMT) is a zinc metallo- enzyme that catalyzes the transfer of a methyl
In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula . In formulas, the group is often abbreviated as Me. This hydrocarbon group occurs in many ...
group from trimethylglycine and a hydrogen ion from homocysteine to produce dimethylglycine and methionine
Methionine (symbol Met or M) () is an essential amino acid in humans. As the precursor of other amino acids such as cysteine and taurine, versatile compounds such as SAM-e, and the important antioxidant glutathione, methionine plays a critical ro ...
respectively:
* Trimethylglycine (methyl donor) + homocysteine (hydrogen donor) → dimethylglycine (hydrogen receiver) + methionine (methyl receiver)
This enzyme belongs to the family of transferases, specifically those transferring one-carbon group methyltransferases. This enzyme participates in the metabolism of glycine, serine
Serine (symbol Ser or S) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated − form under biological conditions), a carboxyl group (which is in the deprotonated − form un ...
, threonine
Threonine (symbol Thr or T) is an amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated −NH form under biological conditions), a carboxyl group (which is in the deprotonated −COOâ ...
and also methionine
Methionine (symbol Met or M) () is an essential amino acid in humans. As the precursor of other amino acids such as cysteine and taurine, versatile compounds such as SAM-e, and the important antioxidant glutathione, methionine plays a critical ro ...
.
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
The autism spectrum, often referred to as just autism or in the context of a professional diagnosis autism spectrum disorder (ASD) or autism spectrum condition (ASC), is a neurodevelopmental condition (or conditions) characterized by difficulti ...
, and schizophrenia to neural tube birth defects such as spina bifida.
See also
* BetaineReferences
Further reading
*External links
* * EC 2.1.1 Enzymes of known structure {{2.1-enzyme-stub