We have developed vibrational Stark effect (VSE) spectroscopy to probe electrostatics and dynamics in biological systems. The strategy involves deploying site-specific vibrational probes (-C�N, -C-D, -C=O and �C-F) whose sensitivity to an electric field is measured in an external electric field.  This gives the magnitude of the vibrational frequency shift associated with an electric field change in a protein, e.g. by making a mutation, changing pH, ligand binding, etc., projected along the bond axis, which is typically determined by x-ray crystallography.  This concept can also be used to estimate the electrostatic contribution to non-covalent X-H��p interactions that stabilize protein structures.  Recently methods have been developed to calibrate the absolute magnitude of the field.  This requires a substantial development of simulations methods in parallel with experiments.  By fully understanding the origins of these effects, they can be applied to obtain information on functionally-relevant fields at the active site of enzymes.

Award Address  (E. Bright Wilson Award in Spectroscopy sponsored by ACS Division of Physical Chemistry). Stark realities

245th National Meeting (2013)

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