Translation diffusion dynamics of protein hydration water and its dynamical coupling with protein dynamics

Nakagawa, Hiroshi   

Protein dynamics is coupled with hydration water dynamics. Here, we examined the translational diffusion dynamics of protein hydration water by MD simulation and incoherent quasi-elastic neutron scattering at various hydration levels. The results of MD simulation show that the diffusion constants of hydration water are significantly suppressed below the hydration level at the percolation transition of hydration water. The diffusion constants are consistent with those estimated by neutron scattering experiments. The experimental data show that the hydration water dynamics can be described by a jump-diffusion model. The residence time in this model is correlated with the hydrogen bond kinetics between water molecules.