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Molybdenum enzyme mediated metabolism of nitrate, and arsenic. Syntheses of new compounds, purification of proteins and their characterization through structural, spectroscopic and reactivity studies.
The role of metal ions in the biological processes is the main focus of our research with the particular emphasis on the reactions catalyzed by molybdenum enzymes particularly the transformation of arsenic and nitrate. Molybdenum enzymes can seriously impact human health by catalyzing redox reactions that triggers disease states. The central component of these enzymes, the molybdenum cofactor (Moco) is a remarkable metal center, defects in synthesis can result in severe physiological abnormalities leading to death. Our studies are directed towards developing a fundamental understanding of the transformation of two oxyanions as they are implicated with cardiovascular diseases and cancer. Our multidisciplinary approach combines chemistry, biochemistry and cellular biology. This page is will provide you some of our adventures, for more details contact me at basu@duq.edu (or 412-396-6345). See my personal page
National Institutes of Health, National Science Foundation, Department of Energy
Organoarsenical – biotransformation and health effects
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Organoarsenicals have a long history of medicinal use. This dates back to the early work of Elrich led to the discovery of salvarsan for treating syphilis. More recently. However, another organoarsenical, roxarsone, has received much attention. We are interesting in understating biotransformation of roxarsone. Our studies show that microbes can readily transform roxarsone releasing inorganic arsenic. The role of inorganic arsenic in cardiovascular disease is well known. We are investigating the proangiogenic potential of roxarsone. In both cases we are interested in understanding the molecular mechanism using a variety of analytical and biochemical tools from chromatography, to proteomics to genomics. We also use high content screening for angiogenesis assay for human cell lines. |
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Using an informatics approach we have classified all nitrate reductases into four distinct sub-famillies: eukaryotic nitrate reductase (Euk-NR), membrane bound nitrate reductase (Nar), cytosolic assimilatory nitrate reductase (Nas) and periplasmic nitrate reductase (Nap). Geonome sequences of epsilon proteobacteria, many of them are pathogenic, have Nap, and no other nitrate reductase. These pathogens can generate toxic nitrogen oxides through nitrate reduction. We have isolated substantial quantities of nitrate reductase (a gel picture and a MALDI mass spectrum is shown) from Sulfurospirillum barnesii for detailed biophysical investigation. A particular interest to us is to evaluate, at the molecular level, how nitrate reduction can influence the reduction of chromium. In parallel, we have isolated and purified arsenate reductase from a haloakalophilic bacterium, Bacillus selenitireducens as a heterodimer. Interestingly, the optimum pH of this enzyme is 9.5 and functions very efficiently at a high salinity (90 g/l NaCl). We are in the process of cloning and expressing this unusual enzyme for detailed biochemical and biophysical investigation that optimally function at an elevated pH and salinity. The arsenate reductase has also been isolated and characterized. | 
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| Many metal centers in biological systems are coordinated by one or more thiol donors. The binding of a thiol residue to a metal ions significantly influences the properties of the metal ion. |
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We have developed a new class of ene-dithiols that binds metal ions very effectively. These molecules were synthesized an ongoing efforts to synthesize certain features of the molybdenum cofactor. Many of the molecules are fluorophoric and we are exploring their optical properties as well as their metal binding, particularly lead binding, properties. |
Molybdenum enzymes such DMSO reductase, sulfite oxidase, nitrate reductase, and arsenite oxidase function via atom transfer reactions. In general, OAT reactions have been investigated for many years, and such reactions have been interpreted in terms of a single transition state model.
Using well-defined model compounds we have demonstrated the multi-step nature of the OAT reactions. We have detected, isolated, and structurally characterized intermediate molecules of OAT reactions. Using surface induced collision mass spectrometry (SID MS) we have measured the bond dissociation energy and experimentally constructed a thermodynamic cycle. In addition, our detailed kinetic analyses have identified the rate-limiting step among these multiple steps of the reactions.
- “Transformation of inorganic and organic arsenic by Clostridium oremlandii sp. nov. strain OhILAs,” In "Incredible Anaerobes: From Physiology to Genomics to Fuels" J. Wiegel, R. Maier and M. Adams (Eds.) Annals New York Academy of Sciences, in press (2008).
- “Design, Syntheses, and Characterization of Dioxo-molybdenum(VI) Complexes With Thiolate Ligands: Effects of Intraligand NH•••S Hydrogen Bonding,” Dalton Transactions, in press (2008).
- “Angiogenic Potential of 3-Nitro-4-Hydroxy Benzene Arsonic Acid (Roxarsone)” Environmental Health Perspective, in press (2008).
- “Synthesis, Electrochemistry, Geometric and Electronic Structure of Oxo-Molybdenum Compounds Involved in an Oxygen Atom Transferring System,” Journal of Inorganic Biochemistry, 102, 748-756 (2008).
- “Biotransformation of 3-Nitro-4-hydroxybenzene arsonic acid (Roxarsone) and Release of Inorganic Arsenic by Clostridium species,” Environ. Sci. Technol. 41, 818-823 (2007).
- “Synthesis, Characterization, and Crystal Structure of the (Me 2Pipdt)Mo(CO) 4 Complex (Me 2Pipdt = N,N’-Dimehylpiperazine-2,3-dithione). A DFT, TDDFT, and TDDFT-PCM Study on Its Electronic Structure, Excited States, and Solvatochromism,” Inorg. Chem., 45, 7494-7502 (2006).
- “Arsenic and Selenium in Microbial Metabolism,” Annual Review in Microbiology, 60, 107-130 (2006).
- “Mechanistic Investigation of the Oxygen Atom Transfer Reactivity of Dioxo-Molybdenum(VI) Complexes,” Chem. Eur. J. 12, 7501-7509 (2006).
- “Solvent Effects in the Geometric Reorganization of an oxo-molybdenum(V) system,” Dalton Transactions, 1419 – 1423 (2006).
- R. L. McNaughton, S. Mondal, V. N. Nemykin, P. Basu, and M. L. Kirk, “Oxomolybdenum Tetrathiolates with Sterically Encumbering Ligands: Modeling the Effect of a Protein Matrix on Electronic Structure and Reduction Potentials,” Inorg. Chem., 44, 8216-8222, (2005).
- “Oxygen Atom Transfer Reactivity from a dioxo-Mo(VI) Complex to Tertiary Phosphine: Synthesis, Characterization and Structure of Phosphoryl Intermediate Complexes,” Inorg. Chem., 44, 7494-7502 (2005).
- “Oxygen Atom Transfer in Models for Molybdenum Enzymes: Isolation and Spectroscopic and Structural Characterization of Intermediates in the Transfer of Oxygen from Mo(VI) to P(III),” Chem. Eur. J.11, 3255-3267, (2005).
- “Factor Regulating Macrophage Endocytosis of Nanoparticles: Implications for Targeted Magnetic Resonance Plaque Imaging,” Atherosclerosis, 178, 67-73 (2005).
- “Isolation, Characterization of an Intermediate in an Oxygen Atom Transfer Reaction and the Determination of the Bond Dissociation Energy,” J. Am. Chem. Soc.,126, 8604-8605 (2004).
Dr. Aaron Barchowsky (U. Pittsburgh) - cellular biology
Dr. Richik Ghosh (Thermo Fisher) - high content imaging
Dr. Michael Hall (Texas A&M) - computation
Dr. Michael Hendrich (Carnegie Mellon U) - spectroscopy
Dr. Martin Kirk (U New Mexico) - spectroscopy
Dr. Julia Laskin (PNNL) - mass spectrometry
Dr. John Stolz (Duquesne U) -- microbiology
Bernd Hammann – Postdoctoral associate
Peter Chovanec – Postdoctoral associate
Eranda Perera - Graduate student
Courtney Sparacino - Graduate student
Kiran Venna – Graduate student
Lauren Marbella- Undergraduate research student
Lawrence Blume – Undergraduate research student
Scott Sadjak – Undergraduate research student
Rebecca Bernard – Undergraduate research student
Barbara Serli – now in Boston raising her family
Ganesh Naik – now a faculty at the College of St. Mary, Omaha NE
Victor Nemykin - now a faculty at University of Minnesota - Duluth, MN
Sujit Mondal - now at PPG
Brian Kail – Ph.D. 2005 , now an Assistant Professor at Westminster College
Raghvendra Sengar - Ph.D. 2004, now a research associate, U. of Pittsburgh
Archana Nigam - M.S. 2004, now a research assistant at U. of Pittsburgh
Walter Rogers - Ph.D. 2003 – deceased, was associate professor at the U of Virginia
Ganna Polshyna - M.S. 2003 now a technician at U Minnesota-Duluth
Matt Moore - M.S. 2000 - now a staff in an environmental consulting farm in California.
Michael Burchianti
Scott Davie -
Kate Welt
Suzanne Denti - now a medical student
Bhavana (Tina) Bhatnagar - now a medical student
Mike Smith
David Yankura
Rukiya
Ali
Christine Bathgate
Stephen Gattuso
Jeremy Snodgrass
Mike Kitz
Mahlet A. Woldetsadik
Hao Vu
Contact: Partha Basu
Associate Professor,
Department of Chemistry and Biochemistry
Duquesne University, Pittsburgh, PA 15282
Office Phone: 412.396.6345 Fax: 412.396-5683
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