Dmethionine

Dmethionine, or D-methionine, is the D-enantiomer of the essential amino acid methionine. Like methionine, it contains a thioether side chain and has the chemical formula C5H11NO2S, but its configuration at the alpha carbon is the mirror image of the naturally occurring L-methionine.

In biology, protein synthesis in humans and most organisms uses the L-form of amino acids. Consequently, D-methionine is not typically incorporated into proteins. D-amino acids can be metabolized through different pathways than their L-counterparts; in mammals, D-methionine may be deaminated or degraded by specific enzymes such as D-amino acid oxidase, rather than entering standard transamination and protein-building processes.

D-methionine is produced and sold in pure form or as part of racemic DL-methionine. In agriculture and animal nutrition, methionine is a critical essential amino acid, and DL-methionine is a common feed-grade supplement used to meet dietary requirements in poultry, pigs, and other livestock. Some formulations emphasize the individual D-enantiomer, while others rely on the mixture, with reported differences in bioavailability depending on species and dietary context.

Safety and regulation of D-methionine-containing products follow the same general considerations as other amino acid supplements and feed additives, with dosages and approvals governed by relevant food, feed, and drug regulations in different jurisdictions.

See also: L-methionine, methionine metabolism, D-amino acids.