Transmethylation

Transmethylation is a biologically important organic chemical reaction in which a methyl group is transferred from one compound to another.

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

Deficiencies of vitamin B12 or folate cause increased levels of circulating homocysteine.

Elevated homocysteine is a risk factor for cardiovascular disease and is linked to the metabolic syndrome (insulin insensitivity).

[1] Transmethylation is decreased sometimes in parents of children with autism.

The recovery of methionine from homocysteine by transmethylation is depicted in reaction 4. The transmethylation cycle is depicted in reactions 1–4.