Research & Scholarship
For the past several years, we have studied the molecular basis of chromium toxicity. Specifically, we are interested in the structure and reactivity of chromium (V). We have synthesized a physiologically relevant oxochromium (V) complex of citrate and have demonstrated facile ligand exchange with picolinate. Our collaborative research with Professors Sandra and Gareth Eaton (University of Denver) and Professor Peter Lay (University of Sydney, Australia), has resulted in two major publications (Carruthers et al, Inorganic Chemistry, 1999, 38, 3529-3534; Cawich et al, Inorganic Chemistry, 2003, 42, 6458-6468; seven Regis students are co-authors). Currently, we are synthesizing new mixed chromium(III) complexes of citrate/picolinate. As chromium(III) has an undefined role in the glucose tolerance factor (GTF), our long-range goals are to develop collaborative research for the evaluation of the new chromium (III) complexes as potential dietary supplements.
Our recent efforts are directed toward the understanding of the molecular basis of aryl diazonium ion toxicity. Aryl diazonium ions are known to induce hemolytic anemia and Heinz bodies in blood. We are currently extending our earlier published work on hemoglobin to electron transfer proteins such as cytochrome c and copper containing proteins (plastocyanin and cytochrome c oxidase). In order to test the outer-sphere (non-bonded) mechanism of electron transfer between ferrocytochrome c and aryl diazonium ions, we have determined the redox potential for a series of aryl diazonium ions by cyclic voltammetry (Mahapatro et al, 241st ACS National Meeting, Anaheim, CA, March 27-31, 2011) and have uncovered a role of the diazohydroxide (anti-diazotate) in the electron transfer reactions of substituted (p-nitro and p-cyano) aryl diazonium ions.
Using nitroxyl (HNO) as a small molecule ligand at the oxygen binding site of cytochrome c oxidase (complex IV of the electron transport chain), presently we are investigating a novel duality in nitroxyl (HNO) redox chemistry -the self oxidation and reduction involving NO and NH2OH. Also, we are exploring the oxidation of biologically important thiols to disulfides by HNO.
Over the past twenty years, my research with Regis undergraduate students has been supported by Research Corporation, Tucson, Arizona (Cottrell College Science grant), Partners in Science grant (Gates Foundation –Research Corporation), ACS-PRF, NIH (AREA), NSF-ILI, Pittsburgh Conference Memorial National Grant, DOE (Rocky-Flats) and by the Western Alliance to Expand Student Opportunities (WAESO, Hispanic Research Center, Arizona State University, Tempe, Arizona) and Regis University (SPARC).
The University of Texas Health Science Center, San Antonio Texas, March 1987-June 1989 (Advisor: Neal Robinson).
Trinity University, San Antonio, Texas, August 1984-February 1987 (Advisor: Michael Doyle)
Hope College, Holland, Michigan, January 1983-July 1984 (Advisor: Michael Doyle)
University of Illinois, Chicago, Illinois, January 1978-December 1979 (Advisor: Jan Rocek)
1. C. M. Cawich, A. Ibrahim, K. Link, A. Bumgartner, M.D. Patro, S. N. Mahapatro, S.Eaton, G.R. Eaton, A. Levina and P.A. Lay and “Synthesis of a Pyridinium Bis[citrato(2-)oxochromate(V) and Its Ligand Exchange Reactions” Inorg. Chem, 2003, 42, 6458-6468.
2. L.M Carruthers, C.L. Closken, K. Link, S.N. Mahapatro, M. Bikram, J-L.Du, S.S. Eaton and G.R. Eaton, “Electron Spin Relaxation in Chromium - Nitrosyl Complexes,”Inorg. Chem. 1999, 38, 3529-3534.
3. M. Senapati, G.P. Panigrahi and S.N. Mahapatro, "Pathways in Chromic Acid Oxidations: III. Kinetics and Mechanism of Oxidation of Malonic Acid," J. Org. Chem., 1985, 50, 3651.
4. M.D. Patro, R.S. Panda, A.K. Panigrahi and S.N. Mahapatro, "Mechanism of Oxidation of Mandelic Acid by Fenton's Reagent," Inorg. Chem., 1984, 23, 4119.
5. M.D. Patro, R.S. Panda, A.K. Panigrahi and S.N. Mahapatro, "The Nature of the Reduction Product in Pyridinium Chlorochromate and Pyridinium Dichromate Oxidations," Inorg. Chim. Acta., 1984, 86, L-5.
6. S. Ch. Dharma Rao, S.N. Padhy, B.N. Misra and S.N. Mahapatro, "Peroxodiphosphate Cleavage by Wheat germ Acid Phosphatase," Indian J. Chem., 1984, 23A, 834.
7. S. Ch. Dharma Rao, A.K. Panda and S.N. Mahapatro, Peroxomonophosphoric Acid Oxidations: Kinetics and Mechanism of Oxidation of Aliphatic Aldehydes," J. Chem. Soc., Perkin Trans. 2., 1983, 769.
8. P.C. Samal, B.B. Pattnaik, S. Ch. Dharma Rao and S.N. Mahapatro, "Kinetics and Mechanism of Chromic Acid Oxidation of Lactic Acid," Tetrahedron, 1983, 39, 143.
9. N. Padhy, B.N. Misra and S.N. Mahapatro, "Peroxodiphosphate Cleavage by Alkaline Phosphatase," Curr. Sci. (India), 1982, 51, 1026.
10. S.N. Padhy, B.N. Misra, H. Pattnaik and S.N. Mahapatro, "Demonstration of Phosphatase Activity: Hydrolysis of Peroxodiphosphate. An Undergraduate Experiment," Indian J. Chem. Educ., 1982, 9, 21.
11. P.C. Samal, B.B. Pattnaik, S. Ch. Dharma Rao and S.N. Mahapatro, "Kinetics and Mechanism of Chromic Acid Oxidation of Lactic Acid," Curr. Sci. (India), 1982, 51, 41.
12. A.K. Panda, S.N. Mahapatro and G.P. Panigrahi, "Kinetics and Mechanism of Oxidation of 3-aminopyridine by Peroxomonophosphotic Acid," Bull. Chem. Soc. (Japan), 1981, 54, 2507.
13. A.K. Panda, S.N. Mahapatro and G.P. Panigrahi, "Studies on Kinetics and Substituent Effect in the Oxidation of Aniline by Peroxomonophosphoric Acid," J. Org. Chem., 1981, 46, 4000.
14. S.N. Mahapatro, A.K. Panda and G.P. Panigrahi, "A Novel Oxidation of 3-Aminopyridine by Peroxomonophosphoric Acid," Curr. Sci. (India), 1980, 49, 227.
15. S.N. Mahapatro, R.S. Panda and G.P. Panigrahi, "On the Mechanism of Peroxodiphosphate Oxidations," Indian J. Chem., 1980, 19A, 905.
16. S.N. Mahapatro and P.K. Misro, "On the Origin of OsO4 Catalysis in Homogenous Red-Ox Reactions of Organic Substrates by IO4-, Fe(CN)63-, ClO3- - and Chloramine-T," Indian J. Chem., 1979, 17A, 404.
17. P.K. Misro, S.N. Mahapatro, and G.P. Panigrahi, "Kinetics and Mechanism of Os(VIII) Catalyzed Oxidation of Cyclohexanone by Alkaline Periodate," Indian J. Chem., 1978, 16A, 1095.
18. S.N. Mahapatro and Neal C. Robinson, "Effect of Changing the Detergent Bond to Bovine Cytochrome C Oxidase Upon its Individual Electron Transfer Steps," Biochemistry, 1989 29, 764.
19. M.P. Doyle, S.N. Mahapatro, R.D. Broene and J.K. Guy, "Oxidation and Reduction of Hemoproteins by Trioxodinitrate (II). The Role of Nitrosyl Hydride and Nitrite," J. Am. Chem. Soc., 1988, 110, 593.
20. M.P. Doyle, M.S. Shanklin, H.Q. Pho and S.N. Mahapatro, "Rhodium (II) Acetate and Nafion-H Catalyzed Decomposition of N-Aryl Diazoamides. An Efficient Synthesis of 2 (3H)-Indolinones," J. Org. Chem., 1988, 53, 1017.
21. M.P. Doyle, S.N. Mahapatro, J.K. Guy, M.R. Hester, C.M. VanZyl and K.L. Boundy, "Electron Transfer Between Hemoglobin and Arenediazonium Salts. Mechanism of Heme-Aryl Iron Complex Formation," Inorg. Chem., 1987, 26, 3387.
22. M.P. Doyle, S.N. Mahapatro, A.C. Caughey, M.S. Chin, M.R. Colsman, N.K. Harn and A.E. Redwine, "Olefin Coordination with Rhodium (II) Perfluoroalkanoates in Solution," Inorg. Chem, 1987, 26, 3070.
23. M.P. Doyle, A.H. Devia, K.E. Basset, J.W. Terpstra and S.N. Mahapatro, "Unsymmetrical Alkenes by Carbene Coupling from Diazirine Decomposition in the Presence of Diazo Compounds," J. Org. Chem., 1987, 52, 1619.
24. M.P. Doyle, J.K. Guy, K.C. Brown, S.N. Mahapatro, C.M. VanZyl and J.R. Pladziewicz, "Outer Sphere One-Electron Reduction of Arenediazonium Salts," J. Am. Chem. Soc., 1987, 109, 1536.
25. M.P. Doyle, S.N. Mahapatro, C.M. VanZyl and M.R. Hester, "Electron Transfer in the Heme Pocket of Hemoglobin," J. Am. Chem. Soc., 1985, 107, 6136.
26. M.P. Doyle and S.N. Mahapatro, "Nitric Oxide Dissociation from Trioxodinitrate (II) in Aqueous Solution," J. Am. Chem. Soc., 1985, 106, 3678.
27. M.P. Doyle, S.N. Mahapatro and S. Van Tran, "Oxidation of Hemoglobin by Arenediazonium Salts: The Influence of Dioxygen," Inorg. Chim. Acta., 1984, 92, 123.
28. S. Ramesh, S.N. Mahapatro, J.H. Liu and J. Rocek, "Three-electron Oxidations. Carbon-13 and Deuterium Isotope Effects in the Co-oxidation of 2-Hydroxy-2methylbutyric Acid and 2-Propanol. Evidence for a Two-Step Mechanism,” J. Am. Chem. Soc., 1981, 103, 5172.
29. S.N. Mahapatro, M. Krumpolc and J. Rocek, "three-electron Oxidations. 17. The Chromium (VI) and Chromium (V) Steps in the Co-oxidation of 2-Hydroxy-2-methylbutyric Acid and 2-Propanol," J. Am. Chem. Soc., 1980, 102, 3700.
30. P.S. Radhakrishnamurti and S.N. Mahapatro, "Kinetic Evidence for Radical Anions in the Oxidation of 4-Nitro and 2,4-Dinitrotoluenes by Alkaline Hexacyanoferrate (III) in Dimethyl Sulphoxide," Indian J. Chem., 1976, 14A, 613.
31. P.S. Radhakrishnamurti and S.N. Mahapatro, "Kinetics and Mechanism of Oxidation of Toluenes by Lead Tetraacetate," Indian J. Chem., 1976, 14A, 478.
32. P.S. Radhakrishnamurti and S.N. Mahapatro, Kinetics and Mechanism of Permanganate Oxidation of Toluene and its Derivatives," Indian J. Chem., 1975, 13, 1294.
33. P.S. Radhakrishnamurti and S.N. Mahapatro, "Kinetics and Mechanism of Oxidation of Ortho and Para Nitro Toluenes by Hexacyanoferrate (III). Unusual Reactivity of Some Hard Substrates," Indian J. Chem., 1975, 13, 1029.
34. S.N. Mahapatro, P.K. Mahapatro, P.L. Nayak and M.K. Raut, "Kinetics of Bromination of Chalcones," J. Ind. Chem. Soc., 1972, 49, 135.