Molecular Description of Surfactant-like Peptide Based Membranes

Abstract

For first time surfactant-like peptide (SLP) based membranes were investigated by full atomistic molecular dynamics simulations. Two different classes of membranes were simulated to quantify the impact of both nonpolar tail and hydrophilic head on the membrane properties. Structural analysis in terms of planar RDFs, density mass profiles, and 2D thickness maps was performed to evaluate the influence of the hydrophobic tail and hydrophilic head in the membrane structural pattern. Unlike what is observed in case of SLP membrane, a lipid membrane has low and short-range local ordering that imposes a significant difference between the two types of membranes. While the lipid membrane interactions are mainly van der Waals for the SLP membrane, both contributions are relevant. This result indirectly implies lower conformational flexibility of SLP and, therefore, their lower potential for live systems. On the basis of the pattern of structuring the membrane in equilibrium, we classified roughly into three different types: (a) those uniform and well ordered, with small variations in thickness and without water inside and therefore no flaw in the hydrogen bond network, (b) those with appreciable variations in structure, with fixed small holes that act as pores for water confinement and defects in the hydrogen bonding network, and (c) a group that has the same properties of the group (a) but present an undulating surface rather than a planar surface.