Methionine metabolism pathway (null)

The methionine metabolism pathway is an essential biochemical system responsible for the utilization, recycling, and transformation of methionine, a sulfur-containing amino acid critical for protein synthesis, methylation reactions, redox balance, and cellular signaling. The pathway comprises the methionine cycle (in which methionine is converted to S-adenosylmethionine, the universal methyl donor), transsulfuration (providing cysteine for glutathione and taurine synthesis), and various salvage and recycling steps. Key enzymes include methionine adenosyltransferase, methionine synthase, and S-adenosylhomocysteine hydrolase. Defects or dysregulation in methionine metabolism are implicated in cancer, cardiovascular disease, chronic liver disease, neurodegeneration, and aging. While not itself a classic drug target, the pathway is modulated by drugs and supplements that affect methionine, methylation, homocysteine, and related metabolites.

Other names

Methionine cycleOne-carbon metabolismTransmethylation pathwayMethionine salvage pathway

Inhibition of methyltransferases (block DNA/histone/protein methylation); Inhibition of methionine adenosyltransferase (affects SAM production); Promotion of homocysteine clearance (cardiovascular protective effects); Supplementation of methyl donors (restores methylation capacity, e.g., betaine or folate).