alphaalanine

Alpha-alanine, or α-alanine, is the α-amino acid 2-aminopropanoic acid. It is one of the 20 standard amino acids used by organisms to synthesize proteins. The term "α" signals that the amino group and carboxyl group are attached to the same carbon (the α-carbon). In nature it exists as two enantiomers, L-alanine and D-alanine; L-alanine is the form predominantly found in proteins.

Chemical properties include a molecular formula of C3H7NO2 and a molecular weight of 89.09 g/mol. It has a three-carbon backbone with a methyl side chain (CH3) and is classified as a nonpolar, aliphatic amino acid. At physiological pH it mainly forms a zwitterion with an isoelectric point near 6.0. Its apparent pKa values are around 2.34 for the carboxyl group and 9.69 for the amino group.

Biologically, alanine is produced via transamination of pyruvate by alanine aminotransferase, using glutamate as the amino donor. It participates in the glucose-alanine cycle, which shuttles ammonia from muscle to liver for disposal. D-alanine is found in some bacterial cell walls and is not the form used in proteins.

Genetically, alanine is encoded by the codons GCU, GCC, GCA, and GCG. It is nonessential in humans, since it can be synthesized endogenously, and it is abundant in many proteins. Industrially, alanine is produced and used as a building block in chemical synthesis.

Name notes: Alpha-alanine may be used interchangeably with α-alanine to distinguish it from beta-alanine (3-aminopropanoic acid).