title: Change in heat capacity accurately predicts vibrational coupling in enzyme catalyzed reactions.
abstract: The temperature dependence of kinetic isotope effects (KIEs) have been used to infer the vibrational coupling of the protein and or substrate to the reaction coordinate, particularly in enzyme-catalyzed hydrogen transfer reactions. We find that a new model for the temperature dependence of experimentally determined observed rate constants (macromolecular rate theory, MMRT) is able to accurately predict the occurrence of vibrational coupling, even where the temperature dependence of the KIE fails. This model, that incorporates the change in heat capacity for enzyme catalysis, demonstrates remarkable consistency with both experiment and theory and in many respects is more robust than models used at present.
authors.affiliation: School of Science, Faculty of Science and Engineering, University of Waikato, Hamilton 3240, New Zealand. Electronic address: varcus@waikato.ac.nz.
authors.forename: Vickery L
authors.initials: VL
authors.lastname: Arcus
authors.affiliation: Department of Biology and Biochemistry, Faculty of Science, University of Bath, Bath BA2 7AY, United Kingdom. Electronic address: c.r.pudney@bath.ac.uk.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Pudney
mesh_terms: D000465:Algorithms; D002384:Catalysis; D004798:Enzymes / Q000737:chemistry* / Q000378:metabolism; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007554:Isotopes / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D008956:Models, Chemical; D013379:Substrate Specificity; D013816:Thermodynamics
chemical_list: D004798:Enzymes; D007554:Isotopes
keywords: Catalysis; Enzyme dynamics; Heat capacity; Promoting motion; Vibrational coupling