Amyloid formation by short peptides in the presence of dipalmitoylphosphatidylcholine membranes

Abstract

The aggregation of two short peptides [RF] and [RF]4 (where R = arginine and F = phenylalanine) with dipalmitoylphosphatidylcholine (DPPC) model membranes was investigated at the air-water interface using the Langmuir technique and vesicles in aqueous solutions. The molar ratio of the peptide and lipid components was varied to provide insights into the peptide-membrane interactions, which might be related to their cytotoxicity.1 Both peptides exhibited affinity to the DPPC membrane interface and rapidly adopted β-sheet rich structures upon adsorption onto the surface of the zwitterionic membrane. Results from adsorption isotherm and small angle X-ray scattering (SAXS) experiments showed changes in the structural and thermodynamics parameters of the membrane with the increase in peptide concentration. Using atomic force microscopy (AFM), we showed the appearance of pores through the bilayer membranes and peptide aggregation at different interfaces, suggesting that the hydrophobic residues might have an effect on both pore size and layer structure, facilitating the membrane disruption and leading to different cytotoxicity effects.