Transmethylation is a biologically important organic chemical reaction in which a

methyl group 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 ...

is transferred from one compound to another. An example of transmethylation is the recovery of

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 ...

from

homocysteine Homocysteine is a non-proteinogenic α-amino acid. It is a homologue of the amino acid cysteine, differing by an additional methylene bridge (-CH2-). It is biosynthesized from methionine by the removal of its terminal Cε methyl group. In the b ...

. In order to sustain sufficient reaction rates during metabolic stress, this reaction requires adequate levels of vitamin B₁₂ and

folate Folate, also known as vitamin B9 and folacin, is one of the B vitamins. Manufactured folic acid, which is converted into folate by the body, is used as a dietary supplement and in food fortification as it is more stable during processing and ...

. Methyl tetrahydrofolate delivers methyl groups to form the active methyl form of vitamin B₁₂ that is required for methylation of homocysteine. Deficiencies of vitamin B₁₂ or

cause increased levels of circulating homocysteine. Elevated homocysteine is a risk factor for cardiovascular disease and is linked to the metabolic syndrome (insulin insensitivity). Transmethylation is decreased sometimes in parents of children with

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 ...

References

Organic reactions {{organic-chem-stub de:Transmethylierung

See also

References