Homocysteine metabolism pathway enzyme

The term "Homocysteine metabolism pathway enzymes" refers collectively to a group of enzymes responsible for the conversion and regulation of homocysteine, a sulfur-containing amino acid that is central to methionine and cysteine metabolism. The two main branches are: 1. Remethylation Pathway – Converts homocysteine back to methionine using 5-methyltetrahydrofolate as a methyl donor via the enzyme methionine synthase, which requires vitamin B12 as a cofactor. The production of 5-methyltetrahydrofolate is catalyzed by methylenetetrahydrofolate reductase (MTHFR), an enzyme whose genetic variants can significantly affect plasma homocysteine levels. 2. Transsulfuration Pathway – Converts homocysteine into cystathionine via cystathionine β-synthase (CBS), then further into cysteine by cystathioninase/cystathionin γ‐lyase; both steps require vitamin B6 as a cofactor. Disruption in these pathways—due to genetic mutations or nutritional deficiencies—can lead to elevated plasma homocysteine (hyperhomocysteinemia), which is associated with increased risk for cardiovascular diseases, neurodegeneration, and congenital anomalies. Therapeutic interventions often involve supplementation with folic acid, vitamins B6/B12, or betaine. Note on correctness: This entry refers not to a single molecular target but rather an entire class/pathway comprising multiple distinct enzymes such as MTHFR, CBS, and others. For structured data purposes it would be more accurate—and scientifically useful—to specify individual targets like "Methylenetetrahydrofolate reductase" or "Cystathionine beta-synthase" rather than this collective term.

Other names

Enzymes of homocysteine metabolismHomocysteine pathway enzymesMethionine cycle enzymesTranssulfuration pathway enzymes

Cofactor supplementation to enhance enzymatic activity or bypass deficiencies in the remethylation or transsulfuration pathways