SINGLE-PARTICLE DYNAMICS OF HYDRATION WATER IN PROTEIN

Incoherent quasi-elastic and inelastic neutron scattering studies of in vivo deuterated C-phycocyanin have been made. At full hydration the high-temperature data can be interpreted using a model where each water molecule is diffusing in a confined space of 3 angstrom in radius. The excess elastic intensity at large Q indicates that a relatively low fraction of water molecules attached to the immediate vicinity of the protein surface is immobile, in agreement with computer simulation. The translational and librational density of states show slight up-shifts from the corresponding bulk cases.