(291e) Elucidating the Role of Ion Concentration and Peptide Charge on the Adsorption Thermodynamics of Model Peptides on Self-Assembled Monolayers, with Molecular Simulation
Though the surface adsorption of biomolecules, from small peptides to large proteins, plays an important part in processes such as surface fouling and biocatalysis, using the full power of Monte Carlo or Molecular Dynamics to understand and control molecular scale driving forces remains a real challenge. This is due in part to the insufficient sampling offered by these methods since the large binding free-energies presented by the protein/surface interface can frustrate the equilibration of relevant probability distributions. To overcome these barriers, our group has previously used parallel tempering metadynamics in the well-tempered ensemble (PTMetaD-WTE) to study the adsorption behavior of explicitly solvated model systems of alpha and beta LK peptides on methyl and carboxyl functionalized self-assembled monolayers (SAMs).1 This method simultaneously enables systems to overcome the aforementioned scaling challenges while retaining the ability to recover unbiased probability distributions for key properties of interest. In this talk we present recent studies using this approach to study how the binding free-energy is influenced by surface properties, peptide composition, and ion strength in solution. We have performed an extended series of LK-peptide adsorption simulations in which we systematically study these effects. We have used simulations of the binding of tryptophan cage and the salivary protein statherin to further investigate these effects. Of particular interest are results showing the strong correlation between the electrostatic interactions at the protein/surface interface and the entropic contribution to the binding free-energy.
 Deighan and Pfaendtner. Langmuir. 29, 7999−8009 (2013).