title: Vibrational Stark Effects of Carbonyl Probes Applied to Reinterpret IR and Raman Data for Enzyme Inhibitors in Terms of Electric Fields at the Active Site.
abstract: IR and Raman frequency shifts have been reported for numerous probes of enzyme transition states, leading to diverse interpretations. In the case of the model enzyme ketosteroid isomerase (KSI), we have argued that IR spectral shifts for a carbonyl probe at the active site can provide a connection between the active site electric field and the activation free energy (Fried et al. Science 2014, 346, 1510-1514). Here we generalize this approach to a much broader set of carbonyl probes (e.g., oxoesters, thioesters, and amides), first establishing the sensitivity of each probe to an electric field using vibrational Stark spectroscopy, vibrational solvatochromism, and MD simulations, and then applying these results to reinterpret data already in the literature for enzymes such as 4-chlorobenzoyl-CoA dehalogenase and serine proteases. These results demonstrate that the vibrational Stark effect provides a general framework for estimating the electrostatic contribution to the catalytic rate and may provide a metric for the design or modification of enzymes. Opportunities and limitations of the approach are also described.
authors.affiliation: Department of Chemistry, Stanford University , Stanford, California 94305-5012, United States.
authors.forename: Samuel H
authors.initials: SH
authors.lastname: Schneider
authors.affiliation: Department of Chemistry, Stanford University , Stanford, California 94305-5012, United States.
authors.forename: Steven G
authors.initials: SG
authors.lastname: Boxer
mesh_terms: D000577:Amides / Q000737:chemistry*; D020134:Catalytic Domain / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000494:pharmacology; D004952:Esters / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D055672:Static Electricity; D013251:Steroid Isomerases / Q000037:antagonists & inhibitors / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D014732:Vibration
chemical_list: D000577:Amides; D004791:Enzyme Inhibitors; D004952:Esters; D013438:Sulfhydryl Compounds; D013251:Steroid Isomerases