个人简介

A.B., 1972, Columbia University Ph.D., 1976, Stanford University NIH Postdoctoral Fellow, 1976–1978, California Institute of Technology Camille and Henry Dreyfus Teacher-Scholar, 1982-87; Alfred P. Sloan Research Fellow, 1983-1987; NIH Research Career Development Award, 1983-1988; Outstanding South Carolina Chemist, SC Section, American Chemical Society, 1988; Russell Research Award for Science, University of South Carolina, 1988; Elected Fellow, American Association for the Advancement of Science, 1989; Editorial Board, Chemtracts-Inorganic Chemistry, 1992-present; Basic Science Research Award, University of South Carolina School of Medicine, 1993; Editor-in-Chief, Journal of Inorganic Biochemistry, 1996-present; Governor's Award for Excellence in Science, 1997; Conference Chair, Tenth International Conference on Cytochrome P450, 1997; Chair, Bioinorganic Subdivision, Inorganic Division, American Chemical Society, 2000; Editorial Board, Journal of Biological Chemistry, 2002-2007; Southern Chemist Award, Memphis Section, American Chemical Society, 2003; Carolina Trustee Professor Award, University of South Carolina, 2004; Chair, Metal Ions in Biology Gordon Research Conference, 2005; Charles H. Stone Award, Charlotte/Piedmont Section, American Chemical Society, 2006; Wyeth/Alumni Lecture, Columbia University, 2006; Elected Fellow, American Chemical Society, 2010; University of South Carolina Educational Foundation Outstanding Service Award, 2012.

研究领域

Biochemistry

Research Areas: Research Areas: Bio-inorganic, bio-physical, and bio-organic chemistry; spectroscopy and mechanisms of action of dioxygen- and peroxide-activating heme iron enzymes and model systems; cytochrome P-450; magnetic circular dichroism spectroscopy. The mechanism of dioxygen activation for insertion into organic molecules is a problem of fundamental importance. The enzymes that catalyze these transformations often require metal ions for activity. Results obtained from the investigation of such metallo-enzymes, in addition to providing insight into their mechanism of action, are of obvious relevance to the design of catalysts for non-enzymatic oxidations. My research interests focus on the structure and function of dioxygen- and peroxide-activating heme iron enzymes. Additional areas of interest include the role of metal ions in enzymatic catalysis and structure, structural and functional model systems, and the application of magnetic circular dichroism, X-ray absorption, and electron paramagnetic resonance spectroscopy to bioinorganic systems. Two experimental approaches are being used: (a) spectroscopic studies to establish the structure of the metal binding site and (b) mechanistic investigations to define the molecular sequence of events involved in catalysis. All appropriate spectroscopic methods are being used to accomplish the first of these two goals. The mechanistic studies involve the use of cryoenzymology and rapid kinetic techniques such as stopped-flow rapid-scanning absorption spectroscopy and freeze-quenching, as well as the determination of important mechanistic parameters. Cytochrome P-450 has been the focus of research in my lab for many years. This heme enzyme has unusual spectroscopic properties and catalytic reactivities relative to other heme enzymes. Its ability to oxygenate an extensive range of substrates has generated considerable interest in its mode of action. In addition to spectroscopically examining the accessible stable states of this enzyme, emphasis is being placed on a detailed understanding of the substrate and ligand binding processes and on attempts to trap out the reactive intermediates responsible for oxygen insertion. In collaboration with Professor Lukasz Lebioda, we are studying two fascinating heme-containing peroxidases from marine sources. One halogenates aromatic substrates (phenols) and the other dehalogenates the resulting halophenol products. Both have unusual spectroscopic and mechanistic properties, relative to other peroxidases, that challenge the conventional structure-function patterns of heme-containing peroxidases. Magnetic circular dichroism (MCD) spectroscopy is a particularly powerful technique for studying heme systems because of its frequent ability to distinguish between porphyrin structures with different axial ligands. To expand the utility of this technique, we are studying the spectroscopic properties of porphyrin complexes of known structure and numerous heme proteins such as nitric oxide synthase, allene oxide synthase and a variety of heme binding and transport proteins. We have both UV-visible and near-IR MCD spectrophotometers, the latter for studying low-energy structure-sensitive charge transfer transitions.

近期论文

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Sun, S.; Du, J.; Sono, M.; Dawson J. H. ""Evidence for direct involvement of substrate TCP radical in functional switching from oxyferrous O2 carrier to ferric peroxidase in the dual function hemoglobin/dehaloperoxidase from Amphitrite ornata"". Biochemistry 2014, in press. Sun, S.; Sono, M.; Wang, C.; Du, J.; Lebioda, L.; Dawson J.H. “Influence of Heme Environment Structure on Dioxygen Affinity for the Dual Function Amphitrite ornata Hemoglobin/Dehaloperoxidase. Insights into the Evolutional Structure-Function Adaptations,"" Arch. Biochem. Biophys. 2014, 545, 108-115. Wang, C.; Lovelace, L.; Sun, S.; Dawson, J.H.; Lebioda, L ""Complexes of Dual Function Hemoglobin/Dehaloperoxidase with Substrate 2,4,6-Trichlorophenol Are Inhibitory and Indicate Halophenol Binding to Compound I,"" Biochemistry 2013, 52, 6203-10. Davydov, R.; Dawson, J.H.; Perera, R.P.; Hoffman, B.M. “Use of Deuterated Camphor as Substrate in (1)H ENDOR Studies of Hydroxylation by Cryoreduced Oxy P450cam Provides New Evidence for the Involvement of Compound I,” Biochemistry, 2013, 52,667-671. Owens, C.P.; Du, J.; Dawson, J.H.; Goulding, C.W. “Characterization of Heme Ligation Properties of Rv0203, a Secreted Heme-Binding Protein Involved in Mycobacterium Tuberculosis Heme Uptake,” Biochemistry 2012, 51, 1518-31. Du, J.; Huang, X.; Sun, S.; Wang, C.; Lebioda, L.; Dawson, J.H. “Amphitrite ornata Dehaloperoxidase (DHP): Investigations of Structural Factors That Influence the Mechanism of Halophenol Dehalogenation Using “Peroxidase-like” Myoglobin Mutants and “Myoglobin-like” DHP Mutants,” Biochemistry 2011, 50, 8172-80. Du, J.; Sono, M.; Dawson, J.H. “The H93G Myoglobin Cavity Mutant as a Versatile Scaffold for Modeling Heme Iron Coordination Structures in Protein Active Sites and Their Characterization with Magnetic Circular Dichroism Spectroscopy,” Coord. Chem. Rev. 2011, 255, 700-716. Du, J.; Perera, R.; Dawson, J.H. “Alkylamine-Ligated H93G Myoglobin Cavity Mutant: A Model System for Endogenous Lysine and Terminal Amine Ligation in Heme Proteins such as Nitrite Reductase and Cytochrome f,” Inorg. Chem. 2011, 50, 1242-1249. Davydov, R.; Osborne, R.L.; Shanmugam, M.; Du, J.; Dawson, J.H.; Hoffman, B.M. “Probing the Oxyferrous and Catalytically Active Ferryl States of Amphitrite ornata Dehaloperoxidase by Cryoreduction and EPR/ENDOR Spectroscopy. Detection of Compound I,” J. Am. Chem. Soc. 2010, 132, 14995-5004. Du, J.; Sono, M.; Dawson, J.H. “Functional Switching of Amphitrite ornata Dehaloperoxidase from O2-Binding Globin to Peroxidase Enzyme Facilitated by Halophenol Substrate and H2O2,” Biochemistry 2010, 49, 6064-6069. Osborne, R.L.; Coggins, M.K.; Raner, G.M.; Walla, M.; Dawson, J.H. “A. ornata Dehaloperoxidase Catalyzes Oxidative Halophenol Dehalogenation by a Mechanism Involving Two Consecutive One-Electron Steps: Characterization and Role of Compound II.,” Biochemistry 2009, 48, 4231-8. Osborne, R. L.; Coggins, M. K.; Terner, J.; Dawson, J. H. “Caldariomyces fumago Chloroperoxidase Catalyzes the Oxidative Dehalogenation of Chlorophenols by a Mechanism Involving Two One-Electron Steps, J. Am. Chem. Soc. 2007, 129, 14838-9. Kim, S. H.; Perera, R.; Hager, L. P.; Dawson, J. H.; Hoffman, B. M. “Rapid-Freeze Quench ENDOR Study of Chloroperoxidase Compound I: The Site of the Radical,” J. Am. Chem. Soc. 2006, 128, 5598-5599. Spolitak, T., J. H. Dawson, and D. P. Ballou. “Reaction of Ferric P450-CAM with Peracids: Kinetic Characterization of Intermediates on the Reaction Pathway.” J. Biol. Chem. 2005, 280, 20300-9