Hydrogen Tunneling in Enzyme Reactions

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Recent studies from this laboratory have established that hydrogen tunneling occurs in the yeast alcohol dehydrogenase and bovine serum amine oxidase reactions. These initial findings suggest that room temperature tunneling may be fundamental feature of enzyme catatlyzed hydrogen transfer reactions. Investigation will be extended in order to: (i) Determine the generality of hydrogen tunneling in enzyme catalyzed H:, H. and H+ reactions, thereby establishing a data base for such behavior; (ii) Characterize the parameters which are likely to control the probability of tunneling, in particular the roles of reaction driving force, E.S binding interactions and protein motion; and (iii) Initiate computational work, with the goal of discriminating among possible models for nuclear tunneling at enzyme active sites. Ultimately, such studies are expected to provide insight into the shape of reaction coordinates at enzyme active sites. Over the past few years the role of quantum mechanical effects in enzyme reactions have gained importance. Although the area of electron tunneling has been the focus of extensive on going investigatrions the phenomenon of hydrogen tunneling in biology has received relatively little attention. It is a particular promising area to pursue to find answer too many features of enzyme catalysis.