The serine family of amino acid metabolism describes how serine, synthesized from either the glycolytic intermediate 3-phosphoglycerate or from glycine via folate-mediated one-carbon transfer, serves as the central branch-point amino acid for producing cysteine. Cysteine biosynthesis proceeds through the transsulfuration pathway, in which methionine (via S-adenosylmethionine and S-adenosylhomocysteine) donates a sulfur-containing intermediate, homocysteine, which condenses with serine to form cystathionine before enzymatic cleavage yields cysteine. This pathway illustrates the interconnection of amino acid metabolism with glycolysis, folate metabolism, and methyl-group transfer chemistry within biochemistry.
The serine family of amino acid metabolism describes how serine, synthesized from either the glycolytic intermediate 3-phosphoglycerate or from glycine via folate-mediated one-carbon transfer, serves…