title: Structural bases of hydrogen tunneling in enzymes: progress and puzzles.
abstract: Accumulating experimental evidence suggests that the occurrence of hydrogen tunneling is likely to be widespread in enzyme-catalyzed reactions. The realization that hydrogen can transfer via tunneling mechanisms has far-reaching implications for our understanding of enzyme catalysis involving proton, hydride or hydrogen atom transfer reactions. The current status of the field is highlighted by three enzyme systems that have been under intensive study in recent years, including soybean lipoxygenase-1, thermophilic alcohol dehydrogenase and dihydrofolate reductase. Particular attention has been devoted to the issues of whether protein dynamics modulate hydrogen tunneling probability and whether the tunneling process contributes to the catalytic power of enzymes.
authors.affiliation: Department of Chemistry, and Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA.
authors.forename: Zhao-Xun
authors.initials: ZX
authors.lastname: Liang
authors.forename: Judith P
authors.initials: JP
authors.lastname: Klinman
mesh_terms: D000426:Alcohol Dehydrogenase / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D001692:Biological Transport / Q000502:physiology; D002384:Catalysis; D004789:Enzyme Activation; D004798:Enzymes / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D006859:Hydrogen / Q000737:chemistry* / Q000378:metabolism*; D007700:Kinetics; D008084:Lipoxygenase / Q000737:chemistry / Q000378:metabolism; D008954:Models, Biological; D008956:Models, Chemical; D008958:Models, Molecular; D011487:Protein Conformation; D013329:Structure-Activity Relationship; D013762:Tetrahydrofolate Dehydrogenase / Q000737:chemistry / Q000378:metabolism
chemical_list: D004798:Enzymes; D006859:Hydrogen; D000426:Alcohol Dehydrogenase; C101084:lipoxygenase L-1; D008084:Lipoxygenase; D013762:Tetrahydrofolate Dehydrogenase