is an α-amino acid with the chemical formula CH3
)COOH. The L
-isomer is one of the 22 proteinogenic amino acids, i.e., the building blocks of proteins. Its codons are GCU, GCC, GCA, and GCG. It is classified as a nonpolar amino acid. L
-Alanine is second only to leucine in rate of occurrence, 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.