Protein hydration and function

Nakagawa, Hiroshi   ; Kataoka, Mikio*

Incoherent neutron scattering (INS) can measure the protein thermal fluctuations under the physiological aqueous environment. The protein dynamics should be characterized with wide time-space ranges. INS is a promising experimental method for analysis of water mobility and protein dynamical transition. Neutron has high permeability in materials, and can observe non-destructively the molecular dynamics. Neutron can give information about vibrational density of states, relaxation and diffusion processes, and mean-square displacements. Molecular Dynamics (MD) simulation gives information on the molecular structure and dynamics with atomic scale, which is complementary to INS. We revealed that the hydration level dependence of the onset of protein dynamical transition is correlated with the percolation transition of hydration water. At the hydration level above the percolation transition, the hydration water dynamics change significantly above the protein dynamical transition temperature. Protein dynamical transition is coupled with the fluctuation of the hydration water network covered over the protein surface.