C6H13NO2

C6H13NO2 is the molecular formula that describes several organic compounds, most notably the branched-chain amino acids leucine and isoleucine. Both are alpha-amino acids containing an amino group, a carboxyl group, and a single chiral carbon with varying side chains. The two compounds share the same empirical formula but differ in structure: leucine is 2-amino-4-methylpentanoic acid and isoleucine is 2-amino-3-methylpentanoic acid. In proteins, only the L-enantiomers of these amino acids are incorporated into polypeptides.

As with many amino acids, in physiological conditions these molecules can exist as zwitterions, with the amino group protonated and the carboxyl group deprotonated. The formula C6H13NO2 is not unique to a single compound; at least these two constitutional isomers have this formula, and their D-enantiomers are not typically used by human biology.

Leucine and isoleucine are classified as essential amino acids in humans, meaning they must be obtained through the diet. They are part of the branched-chain amino acids (BCAAs) group and contribute to protein synthesis, energy metabolism, and various cellular processes. The exact properties and biological roles depend on the specific structure and stereochemistry, which a given molecular formula alone cannot determine.