Decoupling Effect between Dynamics of Proteins and their Hydration Water at Elevated Temperature

Water, as a life solvent, is primary to the energy transfer, biomacromolecules assembly, biological reaction and so on. Particularly, the dynamical transition at ~200 K in proteins, which hydration water is essential for, leads the state of proteins from rigid, nonfunctional state to flexible, functional state. So far, a large number of studies have suggested that the dynamical transition at ~200 K is coupled to the activation of translational motion of the hydration water on the protein’s surface, i.e., the dynamics of proteins and that of their hydration water are coupled. However,by performing elastic neutron scattering experiments of atomic dynamics of proteins with different secondary structures under various instrumental resolutions, we surprisingly find that the dynamics of proteins and that of their hydration water molecules show a resolution-independent and a resolution-dependent behavior at elevated temperature, respectively.These results suggest thatthere actually exists the decoupling effect between dynamics of proteins and that of their hydration water at elevated temperature, and gives a new comprehension in protein dynamical transition.