The hydrophobic effect is central to biomolecular structure and function, ranging from enzymatic activity to protein and membrane assembly. One of the by-products of the resulting compactification is a layer of water molecules lacking full hydrogen bonding coordination while being excluded from the space occupied by the biomolecules. Liberating this constrained water provides a driving force for association processes since returning these hydration shell molecules to the bulk is both enthalpically and entropically favorable. Though necessary for a detailed description of function and dynamics, interrogating hydration water directly presents profound experimental challenges. Using novel transition metal carbonyl vibrational probes covalently attached to protein surfaces and embedded within membranes, we have recently developed the capability to sense water dynamics through carbonyl vibrational relaxation and frequency dynamics (spectral diffusion). We present results for two variants of lysozyme, showing the correlation between site-specific hydration and heterogeneous hydrophobic association.

Ultrafast 2D-IR probes of biomolecule-water interfaces

244th National Meeting (2012)

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