Molecular Dynamics Simulations of the Protein Adsorption Process on Oxides

The adsorption of chymotrypsin and lysozyme on amorphous silica and titania is studied by molecular dynamics (MD) simulations in comparison to experiments. The simulations allow an atomistic view of the adsorption process including long-range interactions, multi-protein effects, contact analysis and surface-induced conformational changes. The surface contact stability is investigated by Steered MD simulations and Atomic Force Spectroscopy experiments. Surface-induced conformational changes are studied by classical and further developed free energy MD methods based on Metadynamics, Replica Exchange Solute Tempering and Umbrella sampling and are compared to circular dichroism experiments. The protein orientation is highly influenced by its dipole moment whereas protein binding motifs are formed mainly by positively charged amino acids. The comparison to the experiment shows that protein-protein interactions and the hydration shell of oxide and protein need to be considered as well.