D-glutamine

D-glutamine is one of the 20 amino acids encoded by the standard genetic code. It is not recognized as an essential amino acid but may become conditionally essential in certain situations, including intensive athletic training or certain gastrointestinal disorders. Its side-chain is an amide formed by replacing the side-chain hydroxyl of glutamic acid with an amine functional group. Therefore, it can be considered the amide of glutamic acid. Its codons are CAA and CAG.