P-113 peptide: New experimental evidences on its biological activity and conformational insights from molecular...

In this article, we report novel and additional results, both experimental and computational, obtained in our laboratories on the peptide P-113. In particular, our experimental results indicate that this peptide is endowed with a high target-cell selectivity towards yeast species, suggesting its potential development as a new drug against oral microbial infections. To provide additional structural insights, we performed several Molecular Dynamics simulations in different conditions. Results suggest that P-113 is a rather compact species presumably because of its highly charged state as emerged from the dramatic increase of internal fluctuation occurring upon point-mutation. The peptide turns out to adopt, in water, a beta-hairpin-like conformation and, in a more hydrophobic environment, is found to be in a (probably slow) equilibrium between α-helix and hairpin conformations. Complexation with Zn(2+) induces a drastic mechanical stabilization, which prevents any conformational organization of the peptide into a biologically active state.