Sulfur amino acids and skeletal muscleNutition and skeletal muscle
Résumé
Methionine and cysteine are the two sulfur amino acids amongst the 20 standard ones incorporated into proteins. In addition to the dietary supply, cysteine can be synthetized from methionine and serine mainly in the liver but not in skeletal muscle. A large part of the whole body flux of methionine transmethylation contributes to the synthesis of creatine and carnitine. Cysteine is the rate-limiting substrate of the synthesis of glutathione and the precursor of taurine, coenzyme A, reduced and oxidized inorganic sulfurs. Only the coenzyme A synthesis pathway is complete in skeletal muscle. Skeletal muscle sulfur amino acid metabolism depends on the arterial availability of methionine and cysteine providers (cysteine, cystine, glutathione, other peptides). Creatine, cartinine, and coenzyme A are essential for ATP production and regeneration, and taurine plays also a role in muscle physiology. Conceptually, supplementations with sulfur amino acids or precursors might palliate some muscle impairments.