Do enzymes offer a special electrostatic environment for catalysing reactions? How is such an environment different from that offered by solvent molecules organized around a reactant? And is the electrostatic environment of enzymes the key to their exceptional catalytic power? These questions, which reside at the intersection of several fields, including catalysis, biochemistry, mechanistic organic chemistry and electrochemistry have puzzled chemists of many stripes for decades, challenging and taunting those who seek to design enzyme mimics. And answering them is difficult, because the inner environment of an enzyme, which features internal fields generated through the combination of charged amino acids and their molecular dipoles, is inaccessible to many of the conventional tools used to measure electrostatic fields. One method by which to study the internal fields within enzymes is vibrational Stark-shift spectroscopy1, which uses probe molecules that have vibrational signatures that are sensitive to electric fields. Thus, one may infer the electric field within a given enzyme by measuring the shift in the vibrational frequency of the probe molecule when compared with the frequency of the probe in a reference environment outside the enzyme.
Anuj Pennathur、Jahan Dawlaty
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Department of Chemistry, University of Southern California, Los Angeles, CA, USA
NSTL
