Elucidating NH2-I3V3A3G3K3-COOH and NH2-K3G3A3V3I3-COOH polypeptide membranes: A classical molecular dynamics study

In this paper, polypeptide membranes composed by surfactant-like peptides were studied by using molecular dynamics simulations. The studied membranes are composed by 15 amino acids, being a hydrophobic part consisting of 3 isoleucine (ILE - I), 3 valine (VAL - V), 3 alanine (ALA - A), 3 glycine (GLY - G), and a hydrophilic one formed by 3 lysine (LYS - K). These amino acids were linked into two different primary sequences, I3V3A3G3K3, with the charged lysine bounded at the C-terminus and K3G3A3V3I3, with the charged lysine bounded at the N-terminus. The density profiles results, the average number of hydrogen bonds, the Coulombic and van der Waals interactions between the peptide-water (PEP-Water) and between each group of peptide residues (PEP-PEP) indicate that, despite the occurrence of much water infiltration (especially in the I3V3A3G3K3 membrane, which has greater porosity than the K3G3A3V3I3 membrane), they still maintain a membrane structure. Our results allow a better understanding of the influence of the interactions between the peptides as well as the role of each group of amino acids residues, peptide terminus and solvent in membrane stability.