Alanine is an a-amino acid with the chemical formula HO2CCH(NH2)CH3. The L-isomer is one of the 20 building blocks of proteins. Its codons are GCU, GCC, GCA, and GCG. It is classified as a non-polar 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.
The alpha -carbon atom of alanine is bound with a methyl group (-CH3), making it one of the simplest a-amino acids. The methyl group of alanine is non-reactive and is thus almost never directly involved in protein function.