X-ray Photon Correlation Spectroscopy Measurements of Protein Diffusion in Concentrated Alpha Crystallin Suspensions*

The dynamics of concentrated suspensions of the crystallin eye-lens protein alpha crystallin was measured using x-ray photon correlation spectroscopy. For pure alpha crystallin suspensions the diffusive dynamics near the peak in the hard sphere structure are well described by a polydisperse hard sphere model. The intermediate scattering factor can be described by a stretched exponential function, and the concentration dependence of the relaxation time agrees with predictions from Langevin dynamics simulations.