Softening of POPC membranes by magainin.

Magainin 2 belongs to the family of peptides, which interacts with the lipid membranes. The present work deals with the effect of this peptide on the mechanical properties of 1-palmitoyl-2-oleoyl-sn-glycerol-3-phosphocholine Giant Unilamellar Vesicle, characterized by the bending stiffness modulus. The bending elastic modulus is measured by Vesicle Fluctuation Analysis at biologically relevant pH and physiological buffer conditions and shows a dramatic decrease with increasing peptide concentration. The observed bilayer softening is interpreted in terms of a continuum model describing perturbations on the membrane organization. Our analysis suggests that the adsorbed peptides give rise to considerable local curvature disruptions of the membrane.