Abstract
The amino acid glycine strongly destabilizes α-helical structure in proteins as well as in model helical peptides. We have investigated the role of a single glycine substitution in a helical host peptide system. Quantitatively, a single glycine → leucine substitution has about one-third of the effect on the stability of helix as does triple substitution of these residues in the middle of the helix. The single glycine perturbs the distribution of helix in the peptide. NMR experiments detect a strong local drop in helix structure at the residues flanking the site of substitution, in addition to overall loss in helicity of the peptide seen at all positions in the chain.