Enantiomeric Effect of d-Amino Acid Substitution on the Mechanism of Action of α-Helical Membrane-Active Peptides

V13K, a 26-residue peptide, has been shown to have strong antimicrobial activity, negligible hemolytic activity, and significant anticancer activity. In the present work, V13K was used as the framework to investigate the influence of helicity, as influenced by d-amino acid substitutions in the center of the peptide polar and non-polar faces of the amphipathic helix, on biological activity. The antibacterial and anticancer activities of the peptides were investigated. Atomic force microscopy and other biophysical methods were used to investigate the effect of peptide helicity on biological activity. The results showed the importance of suitable and rational modification of membrane-active peptides, based on helicity, in optimizing potential biological activity.