Structures of Amino Acids All 20 amino acids found in proteins are a-amino acids The amino group in each is a substituent on the a carbon atom-the one next to the carbonyl group 19 of the amino acids are primary amines,RNH2 Differ in the side chain,the substituent attached to the a carbon Proline,a secondary amine,is the only amino acid whose nitrogen and a carbon atoms are part of the ring Side chain H3N H HH A primary a-amino acid Proline,a secondary a-amino acid All 20 amino acids found in proteins are a-amino acids ▪ The amino group in each is a substituent on the a carbon atom – the one next to the carbonyl group ▪ 19 of the amino acids are primary amines, RNH2 ▪ Differ in the side chain, the substituent attached to the a carbon ▪ Proline, a secondary amine, is the only amino acid whose nitrogen and a carbon atoms are part of the ring Structures of Amino Acids