Molecular understanding of conformational dynamics of a fibronectin module on rutile (110) surface

The conformational dynamics of the 10th type-III module of fibronectin (FN-III₁₀) adsorbed on the perfect and three reduced rutile TiO ₂(110) surfaces with different types of defects was investigated by molecular dynamics (MD) simulations. Stable protein-surface complexes were presented in the four simulated models and were derived from the contributions of direct and indirect interactions of various functional groups in FN-III ₁₀ with the metal oxide layers. A detailed analysis to characterize the overall structural stability of the adsorbed FN-III₁₀ molecule suggests that the bonding strength and the loss of protein secondary structure vary widely, depending on the topology of the substrate surface. The additional adsorption sites exhibiting higher activity, provided by the reduced surfaces, are responsible for the stronger FN-III₁₀-TiO₂ interactions, but too high an interaction energy will cause a severe conformational deformation and therefore a significant loss of bioactivity of the adsorbed protein.