Non-Protein Amino Acids

Synonyms

Noncoded amino acids; Non-proteinogenic amino acids

Keywords

Amino-, and carboxyl- functional groups, amino acids, enantiomer, free amino acids, peptides, racemization, rare amino acids, zwitterions, abiotic syntheses, chemical evolution

Definition

Amino acids are multifunctional organic compounds that contain at least one amino and one carboxyl group attached to a central carbon atom, whose side chains may vary in length and branching as well as in content of other functional groups or aromatic rings. Amino acids may form numerous molecular structures, where the relative position of the amino and carboxyl function allows their general classification as 2-, 3-, 4- etc. (also referred to as α, β, γ, etc.) amino acids. Most amino acids have at least one asymmetric carbon and are chiral. Amino acids are classified as non-protein when they are not part of the 22 such molecules that are translated into proteins by the standard genetic code. They are found in nature, both in...