What Governs Protein Adsorption and Immobilization at a Charged Solid Surface?

The adsorption of hen egg white lysozyme at a model charged surface is studied using fully atomistic molecular dynamics simulations. The simulations are performed over a 90 ns time scale which is sufficient to observe rotational and translational steps in the adsorption process. Electrostatics is found to play a key role in guiding the protein to the favorable binding orientation with the N,C-terminal face against the substrate. However, full immobilization appears to only occur through the strong interaction of Arg128 with the surface, facilitated by the protein's flexibility at the terminal face. Simulated mutation at this residue confirms its crucial role. This work demonstrates that electrostatics alone might not be sufficient to guide the development of material systems that exploit protein adsorption and immobilization.