Internal diffusive and collective motions in proteins studied by neutron scattering

It is well known that water plays a major role in the stability and catalytic function of proteins. Both the effect of hydration water on the dynamics of proteins and the effect of proteins on the dynamics of water have been studied using inelastic neutron scattering. Dynamic neutron scattering is the most direct probe of diffusive and collective protein dynamics on the picosecond-nanosecond timescale. We present here results for C-phycocyanin, which is a globular protein important for photosynthesis. It can be obtained in protonated and deuterated forms. Diffusive motions have been studied using the protonated C-phycocyanin protein. The collective dynamics has been investigated using the fully deuterated C-phycocyanin protein. Comparison is made with results of molecular dynamics simulation.