Surface Hydration Amplifies Single-Well Protein Atom Diffusion Propagating into the Macromolecular Core

The effect of surface hydration water on internal protein motion is of fundamental interest in molecular biophysics. Here, by decomposing the picosecond to nanosecond atomic motion in molecular dynamics simulations of lysozyme at different hydration levels into three components-localized single-well diffusion, methyl group rotation, and nonmethyl jumps-we show that the effect of surface hydration is mainly to increase the volume of the localized single-well diffusion. These diffusive motions are coupled in such a way that the hydration effect propagates from the protein surface into the dry core.