Monte Carlo Simulations of Proteins at Interfaces: From Single Peptides at Simple Surfaces to Proteins at Cell Walls

摘要

Monte Carlo simulations were used to study the conformational changes of negatively charged model peptides dissolved in water adsorbed onto charged surfaces. The peptides consisted of repeating diblock units of aspartic acid (ASP, polar amino acid) and isoleucine (ILE, nonpolar amino acid) residues. Simulations were performed both in vacuum and in water to study the role of water in determining the conformation of the peptide at the surface. Both the flexibility of the peptide molecules and affinities of the surface for peptide segments affect the magnitude of conformational changes. We found that a water patch was retained at the charged surface where the peptide was not in direct contact with the surface. We believed that these water molecules were primarily responsible for giving a particular orientation to the peptide at the surface. The amphiphilic helical peptides used in this study undergo minimal or no loss of helicity at a charged surface. We concluded that helix sequence as well as helix length is important in determining conformational changes of peptides at the charged surface.