2aminopropanoic

2-aminopropanoic acid, commonly known as alanine, is a nonpolar, aliphatic amino acid that occurs widely in proteins. It is one of the 20 standard amino acids encoded by the genetic code and exists as two enantiomers: L-alanine and D-alanine. In proteins, the L-form is predominant; D-alanine is found mainly in some bacterial cell walls and certain non-protein peptides.

Its chemical formula is C3H7NO2 and its molecular weight is 89.09 g/mol. In solution at physiological pH, alanine exists mainly as a zwitterion, with a positively charged amino group and a negatively charged carboxylate. The carboxyl group and amino group have typical pKa values of about 2.34 and 9.69, respectively, giving an isoelectric point near 6.0.

Alanine is non-essential for humans, as it can be synthesized in the body. It is produced primarily from pyruvate through transamination with glutamate, catalyzed by alanine aminotransferase. The alanine cycle describes the transport of alanine from muscle to liver, where it is converted back to pyruvate for gluconeogenesis and then returned to muscle.

Biologically, alanine contributes to protein structure via its methyl-bearing side chain and participates in cellular nitrogen and carbon metabolism. It is also used in peptide synthesis and serves as a model substrate in enzymology and metabolism studies. In most organisms, L-alanine is the biologically active form incorporated into proteins, while D-alanine plays a specialized role in some bacterial systems.