Optical Activity of Amino Acids, Peptides, and Proteins

Abstract

The optical activity of proteins is due to two factors — the asymmetry of the polypeptide chain and the asymmetry at the α-carbon atoms in the amino acid residues. If the asymmetric order of folding of the chain is destroyed, the protein is still optically active because of the rotatory contributions of all the asymmetric α-carbon atoms in the disorganized chain. Although we are interested chiefly in the effects of the higher-order structures on optical activity, it is also important to know the contributions of the many asymmetric carbon atoms. For this reason, the optical activity of natural α-amino acids will be discussed briefly.