Coherent X-ray Scattering Reveals Nanoscale Fluctuations in Hydrated Proteins

Abstract

Hydrated proteins undergo a transition in the deeply supercooled regime, which is attributed to rapid changes in hydration water and protein structural dynamics. Here, we investigate the nanoscale stress relaxation in hydrated lysozyme proteins stimulated and probed by X-ray Photon Correlation Spectroscopy (XPCS). This approach allows us to access the nanoscale dynamic response in the deeply supercooled regime (T = 180 K) which is typically not accessible through equilibrium methods. The relaxation time constants exhibit Arrhenius temperature dependence upon cooling with a minimum in the Kohlrausch-Williams-Watts exponent at T = 227 K. The observed minimum is attributed to an increase in dynamical heterogeneity, which coincides with enhanced fluctuations observed in the two-time correlation functions and a maximum in the dynamic susceptibility quantified by the normalised variance ${\chi }_T$. Our study provides new insights into X-ray stimulated stress relaxation and the underlying mechanisms behind spatio-temporal fluctuations in biological granular materials.

References in corpus (4)

• Observation of Fragile-to-Strong Dynamic Crossover in Protein Hydration Water
• Glass transition in biomolecules and the liquid-liquid critical point of water
• Resolving molecular diffusion and aggregation of antibody proteins with megahertz X-ray free-electron laser pulses
• Relaxation dynamics induced in glasses by the absorption of hard X-ray photons

Cited by in corpus (1)

• Coherent X-rays reveal anomalous molecular diffusion and cage effects in crowded protein solutions