ORIGIN OF THE ANOMALOUS DIFFUSION OBSERVED BY MD SIMULATION AT THE PROTEIN-WATER INTERFACE

Our recent molecular dynamics simulations of water-plastocyanin system s have shown evidence of a sublinear trend in time, for long times, of the mean square displacements of water oxygens. In this Letter, we ex tensively analyze the role played by the spatial (protein surface roug hness) and temporal (distribution of water residence times) disorder i ntrinsic to the systems investigated in determining the observed anoma lous diffusion process. Moreover, the occurrence of a correlated motio n of waters, due to the glassy character of the protein-water interfac e, is explored in the framework of mode coupling theory.