Probing Cage Relaxation in Concentrated Protein Solutions by X-Ray Photon Correlation Spectroscopy

Diffusion of proteins on length scales of their size is crucial for understanding the machinery of living cells. X-ray photon correlation spectroscopy (XPCS) is currently the only way to access long-time collective diffusion on these length scales, but radiation damage so far limits the use in biological systems. We apply a new approach to use XPCS to measure cage relaxation in crowded a-crystallin solutions. This allows us to correct for radiation effects, obtain missing information on long time diffusion, and support the fundamental analogy between protein and colloid dynamical arrest.

Automated summary

Studying the diffusion of proteins in cells is essential for understanding biological mechanisms. X-ray photon correlation spectroscopy (XPCS) is currently the only method to study long-time collective diffusion on the scale of proteins, but its application in biological systems has been limited due to radiation damage. In this study, a new approach using XPCS to measure cage relaxation in crowded α-crystallin solutions was applied, allowing for correction of radiation effects, obtaining missing information on long-time diffusion, and supporting the fundamental analogy between protein and colloid dynamical arrest.