S-Methylcysteine is the amino acid with the nominal formula CH3SCH2CH(NH2)CO2H. It is the S-methylated derivative of cysteine. This amino acid occurs widely in plants, including many edible vegetables.
Natural occurrence
S-Methylcysteine is not genetically coded, but it arises by post-translational methylation of cysteine. One pathway involves methyl transfer from alkylated DNA by zinc-cysteinate-containing repair enzymes such as methylated-DNA-protein-cysteine methyltransferase. S-Methylcysteine sulfoxide is an oxidized derivative of S-methylcysteine that is found in onions. MetaCyc contains a list of biochemical reactions producing and consuming this substance.
Other chemical properties Beyond its biological context, S-methylcysteine has been examined as a chelating agent.
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