Homocysteine Methylation Pathway Enzyme System (N/A)

The homocysteine methylation pathway enzyme system refers to the network of enzymes and associated cofactors responsible for the metabolism of homocysteine, a sulfur-containing amino acid, through methylation and related biochemical reactions. This system is central to one-carbon metabolism, which is crucial for DNA synthesis, repair, epigenetic regulation (via DNA and histone methylation), neurotransmitter synthesis, phospholipid production, and antioxidant defense. Key enzymes include Methionine Synthase (MTR), Methylenetetrahydrofolate Reductase (MTHFR), Betaine-Homocysteine Methyltransferase (BHMT), Methionine Adenosyltransferase (MAT), S-Adenosylhomocysteinase (AHCY), Cystathionine β-Synthase (CBS), and Cystathionin γ-Lyase (CTH/CGL). Disruption of this pathway leads to hyperhomocysteinemia, an independent risk factor for cardiovascular disease, neurodegeneration, and birth defects. Homocyteïne levels influence global DNA/histone/protein/lipid/neurotransmitter méthylations through modulation of intracellular SAM/SAH ratios—affecting gene expression patterns critical for development/homeostasis/disease susceptibility.

Other names

Homocysteine metabolism pathwayOne-carbon metabolismMethionine cycle

Enzyme activity modulation (activation/inhibition), Cofactor supplementation