The Department of Molecular and Cellular Biochemistry
Russ HilleProfessor |
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Ph.D. - Rice University |
Post Doctoral - University of Michigan |
Research In Dr. Hille's laboratory focuses on the reaction mechanisms of oxidoreductase enzymes - particularly those possessing molybdenum or flavin in their active sites - and biological electron transfer. The molybdenum-containing enzymes catalyze the incorporation of oxygen into a variety of organic and inorganic compounds, and constitute an important enzyme class within the oxidoreductases. These enzymes are only poorly understood in comparison to other biological systems that contain heme, flavin, non-heme iron or copper. Furthermroe, in utilizing water rather than dioxygen as the source of the oxygen atom incorporated into product, and in generating rather than consuming reducing equivalents, the molybdenum enzymes carry out hydroxylation reactions is a way that is fundamentally different from all other types of enzyme. The overall aim of our work is to understand in detail how the reaction takes place. Working with representative members of each of the three major families of molybdenum enzymes, we are presently examining the catalytic sequences of these enzymes in detail, identifying and characterizing reaction intermediates for members of each class of enzyme. These studies include kinetic, spectroscopic and mutagenic studies to gain further insight into the basic elements of catalysis at play for each class of enzymes, as well as modeling of reaction intermediates and transition states using ab initio computational methods. We are also interested in the reaction mechanism flavin-containing amine oxidases (including monoamine oxidase and trimethylamine dehydrogenase), a group of enzymes that catalyze the oxidative deamination of a variety of biologically important amines. Again, the overall aim is to understand the catalytic cycle at its most fundamental chemical level. In the case of trimethylamine dehydrogenase (TMADH) the reducing equivalents obtained by amine oxidation are subsequent reduction of an electron-transferring flavoprotein (ETF). We are presently engaged in identifying the specific roles of active-site residues for each of the several steps in the overall reaction mechanism by site-directed mutagenesis. Time-resolved crystallographic studies have also been initiated in an effort to follow the chemistry of amine oxidation within the crystal. We are interested in the protein-protein interaction between TMADH and its physiological partner ETF, and have also begun to work on two other proteins having a high degree of sequence homology to TMADH: the BaiC and BaiH gene products from Eubacterium sp. VPI 12708. The genes for these two proteins are found in a single cholic acid-inducible operon, and are thought to be involved in the biosynthesis of deoxycholate from cholic acid. We presently have a suitable expression system for BaiH and are working to identify the reaction catalyzed by this enzyme and the degree of similarity it shares with TMADH in terms of both its catalytic and biophysical properties. |
Recent Publications: |
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Pauff JM, Hemann CF, Junemann N, Leimkuhler S and Hille R (2007) "The Role of Arginine 310 in Catalysis and Substrate Specificity in Xanthine Dehydrogenase from Rhodobacter capsulatus" J Biol Chem 282(17):12785-90. Pei P, Horan MP, Hille R, Hemann CF, Schwendeman SP, Mallery SR (2006) "Reduced nonprotein thiols inhibit activation and function of MMP-9: implications for chemoprevention" Free Radic Biol Med 41(8):1315-24. Hemann C, Ilich P, Stockert AL, Choi EY and Hille R (2005) "Resonance Raman studies of xanthine oxidase: The reduced enzyme-product complex with violapterin" J Phys Chem B 2005 109(7):3023-31. Hemann C, Hood BL, Fulton M, Hansch R, Schwarz G, Mendel RR, Kirk ML and Hille R (2005) "Spectroscopic and kinetic studies of Arabidopsis thaliana sulfite oxidase: nature of the redox-active orbital and electronic structure contributions to catalysis" J Am Chem Soc 127(47):16567-77. Stuehr DJ, Wei CC, Wang Z and Hille R (2005) "Exploring the redox reactions between heme and tetrahydrobiopterin in the nitric oxide synthases" Dalton Transactions (21):3427-35. Astashkin AV, Hood BL, Feng C, Hille R, Mendel RR, Raitsimring AM and Enemark JH (2005) "Structures of the Mo(V) forms of sulfite oxidase from Arabidopsis thaliana by pulsed EPR spectroscopy" 44(40):13274-81. Anderson RF, Hille R, Shinde SS and Cecchini G (2005) "Electron transfer within complex II. Succinate: ubiquinone oxidoreductase of Escherichia coli" J Biol Chem 280(39):33331-7. Hemann CF, Ilich I, Stockert AL, Choi E-Y and Hille R (2005) "Resonance Raman studies of xanthine oxidase: the reduced enzyme product complex with violapterin" J Phys Chem B 109:3023-31. Doonan CH, Stockert A, Hille R and George GN (2005) "Nature of the catalytically labile oxygen at the active site of xanthine oxidase" J Am Chem Soc 127(12):4518-22. Shi W, Mersfelder J and Hille R (2005) "The interaction of trimethylamine dehydrogenase with electron- transferring flavoprotein" J Biol Chem 280(21):20239-46. Cobb N, Conrads T and Hille R (2005) "The reaction of reduced dimethylsulfoxide reductase with dimethylsulfoxide" J Biol Chem 280(12):11007-17. Wei CC, Wang ZQ, Durra D, Hemann C, Hille R, Garcin ED, Getzoff ED and Stuehr D (2005) "Three nitric-oxide synthases differ in their kinetics of tetrahydrobiopterin radical formation, heme-dioxyreduction and arginine hydroxylation" J Biol Chem 280(10):8929-35. Hille R (2005) "Molybdenum-containing hydroxylases" Arch Biochem Biophys 433(1):107-16. Wei C-C, Wang Z-Q, Arvai AS, Hemann C, Hille R, Getzoff ED and Stuehr DJ (2003) "Structure of tetrahydrobiopterin tunes its electron transfer to the heme-dioxy intermediate in nitric oxide synthase" Biochemistry 42:1969-77. Hemann CF, Ilich P and Hille R (2003) "Molecular vibrations of solvated lumazines. Ab initio reaction field calculations and experiment" J Phys Chem 107:2139-55. Anderson GL, Ellis PJ, Kuhn P, and Hille R (2002) In Environmental Chemistry of Arsenic: Oxidation of Arsenite by Alcaligenese faecalis. (Frankenberger, W.T., ed.) Marcell Dekker, New York, pp. 343-61. Conrads T, Hemann CF, George GN, Pickering IJ, Prince RC and Hille R (2002) "XAS and resonance raman studies of the molybdenum center of arsenite oxidase" J Am Chem Soc 124:11276-7. Hille R (2002) "Molybdenum and tungsten in biology" Trends Biochem Sci 27:360-7. Stockert AL, Shinde S, Anderson RF and Hille R (2002) "The reaction mechanism of xanthine oxidase. Evidence for two-electron chemistry rather than sequential one-electron steps" J Am Chem Soc 124:14554-5. |
Last Modified: 03/22/06