Molecular Dynamics Simulation Of Protein Adsorption On Solid-liquid Interface

Protein adsorption on to solid surface is important in many industrial and medical processes. Although much progress has been achieved in recent years, it is still very difficult to predict a priori the adsorption rates, orientations, or conformational changes, all of which are vital to understanding, controlling, and manipulating protein-based biological events at interface.Molecular dynamic (MD) simulation is a powerful tool for studying interface phenomena such as adsorption. Positions of all atoms are known in MD simulations, so we can investigate adsorption mechanism and adsorption kinetics in the system at molecular lever.Considering the characteristic of protein, we proposed rigid-body model in MD simulation of poly-10-lysine adsorption at solid-liquid interface. Using periodic boundary condition, simulations are proceeded in NVT system.The initial velocities are generated with Maxwell speed distribution. Spherical cutoff are adopted for potential trucation.An minimum image convention in a two-dimensional system and grouping in the central unit cell are proposed to improve the calculation speed. Time is reduced 30%~40% approximately.The results of molecular dynamic simulation shows that the dihedral angles φ and ψ in main chain change more or less during adsorption and some anglesφ go beyond the scope of αhelix so that the helical structure of poly-10-lysine is destroyed in some degree; The structure of side chains changes obviously too. Therefore the conformation of protein can change and even the protein can be inactivated in the process of adsorption.The adsorption of poly-10-lysine on silica nanoparticles and titanium oxide nanoparticles shows the content ofαhelix decrease after adsorption.The result of simulation provided a theoretical foundation for this experimental result.