Proteins exhibit a wide range of dynamics, from slow conformational rearrangements to faster fluctuations in local structure and hydration environments. Here, we leverage ultrafast 2D-IR spectroscopy in conjunction with protein-surface labeling techniques to provide unique access to this key interfacial region that is traditionally difficult to access experimentally. Through the frequency-frequency correlation function (a 2D-IR observable that describes the thermal fluctuations around a probe molecule) the hydration and protein dynamics can be observed simultaneously. Glycerol-D2O solutions permit controllable viscosity while leaving the protein fully hydrated. The hydration dynamics and protein dynamics show a nearly identical dependence on the bulk solution viscosity, suggesting that the hydration water acts as a coupling agent between the protein and the dynamical fluctuations of the solvent. Exploring the coupling between the dynamic �tiers� of proteins promises to deepen our understanding of the interplay between biomolecules and their surroundings.

Ultrafast dynamics at the protein-water interface studied with 2D-IR spectroscopy

244th National Meeting (2012)

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