个人简介

B.S., 1986, Brigham Young University Ph.D., 1991, University of Wisconsin-Madison Postdoctoral, 1991-1993, Oregon State University

研究领域

Biochemistry

The following subject has been presented during the departamental seminar on Nov.1, 2006. Title: “Use of the iclicker personal response system as an interactive tool in the chemistry classroom”. Abstract: “Personal response systems” are hand-held devices that allow students to interact and receive feedback by keying in answers to questions presented in lecture classes. The popularity of these devices has increased substantially in the last several years. Recently, USU adopted one such system, the “iclicker”, as the standard platform for use in courses taught on campus. In this seminar, I will present an overview of how the iclicker system works, and how I personally have been using it in attempts to enhance participation, interaction, feedback, and assessment in the classroom. I will also provide a tutorial on how questions are prepared, delivered, and how the results are accessed for assessment, assignment of participation and/or graded points, and how they are made available to the students for review. I will provide iclicker units to the seminar attendees so that they can use them “hands-on” to assess their functionality and capabilities. In our laboratory we are investigating microbial pathways of short-chain hydrocarbon oxidation and the biochemical, mechanistic, and spectroscopic properties of the enzymes involved in these pathways. One research project concerns the physiology and biochemistry underlying the microbial oxidation of alkenes. For these studies we are utilizing a soil bacterium, Xanthobacter strain Py2, which is able to grow using either ethylene, propylene, or butylene as its carbon and energy source. The metabolism of alkenes is initiated by a monooxygenase that inserts O2 into the olefin bond, forming the corresponding epoxides in a stereospecific manner. The epoxides are further metabolized by the action of a novel carboxylase that opens the epoxide ring and adds CO2 to the alpha carbon atom, forming beta-keto acids as products. Alkene monooxygenase and epoxide carboxylase represent new and largely uncharacterized enzymes of potential biotechnological and environmental interest, and a major goal of this project is to biochemically and mechanistically characterize these enzymes. We are also characterizing the genes involved in alkene and epoxide metabolism and studying how the expression of the alkene-oxidizing enzymes is regulated at the molecular level. The other research emphasis of our laboratory concerns bacterial acetone metabolism. Acetone is a toxic molecule that is synthesized industrially and formed biologically during bacterial fermentation and mammalian starvation. A number of bacteria are able to grow with acetone as a source of carbon and energy. In addition, acetone is formed an intermediate in the metabolism of propane and isopropanol by some bacteria. Bacterial pathways of acetone metabolism and the biochemical properties of acetone-metabolizing enzymes are poorly understood. We are attempting to advance the state of knowledge of these areas by studying the pathway of acetone metabolism and the properties of the acetone-metabolizing enzyme(s) of Xanthobacter strain Py2.

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Boyd, J. M. and Ensign, S. A. 2005 “ATP-dependent Enolization of Acetone by Acetone Carboxylase from Rhodobacter capsulatus” Biochemistry, 44, 8543-8553. Wampler, D. A. and Ensign, S. A. 2005 " Photoheterotrophic metabolism of Acrylamide by a Newly Isolated Strain of Rhodopseudomonas palustris" Appl. Environ. Microbiol. 71, 5850-5857. Boyd, J. M. and Ensign, S. A. 2005 “Evidence for a Metal-Thiolate Intermediate in Alkyl Group Transfer from Epoxypropane to Coenzyme M and Cooperative Metal Ion Binding in Epoxyalkane:CoM Transferase” Biochemistry, 44, 13151-13162. Pandey,A. S, Nocek,B., Clark, D.D. Ensign, S.A. and Peters, J. W. 2006 “Mechanistic Implications of the Structure of the Mixed-Disulfide Intermediate of the Disulfide Oxidoreductase, 2-Ketopropyl-Coenzyme M Oxidoreductase/Carboxylase” Biochemistry, 45, 113-120. Krishnakumar,A. M. Nocek, B. P., Clark, D.D. Ensign, S. A. and Peters, J.W. 2006 “Structural Basis for Stereoselectivity in the (R)- and (S)-Hydroxypropylthioethanesulfonate Dehydrogenases” Biochemistry, 45, 8831-8840. Ensigns, S.A. 2006 “Revisiting the glyoxylate cycle: alternative pathways for microbial acetate assimilation” Molecular Microbiology, 61, 274-276. Boyd, J. M., Ellsworth, A., and Ensign, S. A. 2006 “Characterization of 2-Bromoethanesulfonate as a Selective Inhibitor of the Coenzyme M-Dependent Pathway and Enzymes of Bacterial Aliphatic Epoxide Metabolism” The Journal of Bacteriology, 188, 8062-8069. Krishnakumar, A.M. Sliwa, D. James A. Endrizzi, J. A.Eric S. Boyd, E.S., Ensign, S.A. and Peters, J.W. 2008 “Getting a Handle on the Role of Coenzyme M in Alkene Metabolism” Microbiol. Mol. Biol. Rev. 2008 72: 445-456.