Inbiochemistry, adehydroamino acid or α,β-dehydroamino acid is an amino acids, usually with a C=C double bond in its side chain. Dehydroamino acids are not coded by DNA, but arise viapost-translational modification.^[1]

A common dehydroamino acid isdehydroalanine, which otherwise exists only as a residue in proteins and peptides. The dehydroalanine residue is obtained dehydration ofserine-containing protein/peptide (alternatively, removal of H₂S fromcysteine). Another example is dehydrobutyrine, derived from dehydration ofthreonine.

Generally, amino acid residues are unreactive toward nucleophiles, but the dehydroamino acids are exceptions to this pattern. For example, dehydroalanine adds cysteine and lysine to form covalent crosslinks.^[2]

An unusual dehydroamino acid isdehydroglycine (DHG) because it does not contain a carbon-carbon double bond. Instead it is theimino acid ofglyoxalic acid. It arises by the radical-induced degradation oftyrosine.^[3]

Dehydroamino acids do not feature amino-alkene groups, but the corresponding N-acylated derivatives are known. These derivatives, also known as N-acylamino acrylates, are prochiral substrates forasymmetric hydrogenation. The 2001Nobel Prize in Chemistry was awarded toWilliam S. Knowles for his synthesis ofL-DOPA from the N-acylacrylate.^[4][5]

• Amino acids