The Binding Mechanism of an Experimentally Identified Platinum-binding Peptide by Molecular Dynamics Simulation

The technological potential of proteins that recognize specific fluid/solid interfaces is immense - just a few examples of relevance here are the use of designed peptides for the fractionation of carbon nanotubes and the assembly of nanoscale building blocks to form complex nanostructured materials and electronic circuits. Realising this potential requires far greater fundamental understanding of the interaction between these peptides and solid surfaces and an ability to predict the associated free energy of adsorption. In this contribution, long (i.e. up to 20 ns) molecular dynamics simulations have been used to elucidate the fundamentals of the adsorption of an experimentally identified platinum-binding peptide at the solvated {111} platinum surface. It is observed that the initial phase of the adsorption process is mediated by the formation of hydrogen bonds between the peptide and the ordered water layers at the solid-water interface. Following anchoring of the peptide at the interface by hydrogen bonding between the first water layer and a single hydrophilic group, more hydrophobic groups of the peptide penetrate the water layer at a more leisurely rate and engage directly with the platinum surface. These interactions lock the peptide to the surface. The implications of our findings for the evaluation of adsorption free energies are also outlined.