It is exceedingly difficult to probe the fundamental dynamics of protein-water interactions site-specifically at the interface. Using a highly sensitive vibrational labeling approach based on introducing small transition metal carbonyl probes, we have been able to use two-dimensional infrared spectroscopy to sense both water and protein dynamics directly at the interface. Previously we observed site-specific heterogeneous hydration dynamics and dehydration using labeled homologous proteins (human and hen lysozymes). We have recently quantified the modest slowdown of water dynamics at the protein interface using spectral dynamics uniquely available from 2D-IR, as well as a direct observation of the coupling between protein and hydration water dynamics to the bulk solvent (modulated with glycerol). Here, we present the first 2D-IR results of systematic protein crowding, where we observe unambiguous evidence for a dynamical transition that arises from the coupled, cooperative hydration environments of macromolecular crowders.

Hydration, slaving, and crowding dynamics probed at the protein-water interface with 2D-IR spectroscopy

245th National Meeting (2013)

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