Alanines

Alanine is an α-amino acid with the chemical formula HO2CCH(NH2)CH3. The L-isomer is one of the 20 proteinogenic amino acids, i.e. the building blocks of proteins. Its three letter code is ala, its one letter code is A, and its codons are GCU, GCC, GCA, and GCG. It is classified as an nonpolar amino acid. L-alanine is second only to leucine, accounting for 7.8% of the primary structure in a sample of 1,150 proteins. D-alanine occurs in bacterial cell walls and in some peptide antibiotics.

Structure
The α-carbon atom of alanine is bound with a methyl group (-CH3), making it one of the simplest α-amino acids with respect to molecular structure and also resulting in alanine being classified as an aliphatic amino acid. The methyl group of alanine is non-reactive and is thus almost never directly involved in protein function.

Biosynthesis
Alanine is most commonly produced by reductive amination of pyruvate. Because transamination reactions are readily reversible and pyruvate pervasive, alanine can be easily formed and thus has close links to metabolic pathways such as glycolysis, gluconeogenesis, and the citric acid cycle. It also arises together with lactate and generate glucose from protein via the alanine cycle.