Percolation of hydration water as a control of protein dynamics

Nakagawa, Hiroshi   ; Kataoka, Mikio

Protein cannot work without hydration water. In order to clarify the effect of hydration water on protein dynamics, incoherent neutron scattering and MD simulation are performed for a protein, staphylococcal nuclease. We found that the hydration level dependence of the onset of protein dynamical transition is correlated with the percolation transition of hydration water. Hydration water dynamics change above the transition as well. The percolation of hydration water is essential to activate the anharmonic motions of a protein, which are responsible for protein function.