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, I(3)V(3)A(3)G(3)K(3), with the charged lysine bounded at the C-terminus and K(3)G(3)A(3)V(3)I(3), 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 I(3)V(3)A(3)G(3)K(3) membrane, which has greater porosity than the K(3)G(3)A(3)V(3)I(3) 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. (C) 2019 Elsevier B.V. All rights reserved.