The yellow from the egg - non-equilibrium dynamics of protein solutions studied with high brilliance X-ray sources

Non-equilibrium processes such as liquid-liquid phase separation and gel formation facilitate structural and functional organization relevant in biology and food science. The processes involve a hierarchy of length and timescales which require the understanding of the structure and dynamics on length scales ranging from single proteins up to the network mesh size (hundreds of nanometers to micrometers), and timescales of microseconds to hundreds of seconds. This constitutes a considerable challenge both for simulations and experiments with the need to capture especially nonequilibrium phenomena such as aging and dynamical heterogeneity.

Making use of the coherence properties of modern X-ray sources we apply state-of-the-art X-ray photon correlation spectroscopy (XPCS) at storage ring and X-ray free electron laser facilities and map out the non-equilibrium dynamics in protein solutions. We address challenges such as radiation damage and the ever-increasing data volume arising in these experiments. Results from liquid-liquid phase separation in IgG solutions to scaling laws in gelation from egg-white and egg-yolk will be discussed including the prospects and outlook of XPCS experiments at the high coherence storage rings ESRF-EBS and PETRA IV.

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