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Ha Y, Tenderholt AL, Holm RH, Hedman B, Hodgson KO, Solomon EI. Sulfur K-edge X-ray absorption spectroscopy and density functional theory calculations on monooxo Mo(IV) and bisoxo Mo(VI) bis-dithiolenes: insights into the mechanism of oxo transfer in sulfite oxidase and its relation to the mechanism of DMSO reductase. J Am Chem Soc 2014; 136:9094-105. [PMID: 24884723 PMCID: PMC4073832 DOI: 10.1021/ja503316p] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Indexed: 12/25/2022]
Abstract
Sulfur K-edge X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations have been used to determine the electronic structures of two complexes [Mo(IV)O(bdt)2](2-) and [Mo(VI)O2(bdt)2](2-) (bdt = benzene-1,2-dithiolate(2-)) that relate to the reduced and oxidized forms of sulfite oxidase (SO). These are compared with those of previously studied dimethyl sulfoxide reductase (DMSOr) models. DFT calculations supported by the data are extended to evaluate the reaction coordinate for oxo transfer to a phosphite ester substrate. Three possible transition states are found with the one at lowest energy, stabilized by a P-S interaction, in good agreement with experimental kinetics data. Comparison of both oxo transfer reactions shows that in DMSOr, where the oxo is transferred from the substrate to the metal ion, the oxo transfer induces electron transfer, while in SO, where the oxo transfer is from the metal site to the substrate, the electron transfer initiates oxo transfer. This difference in reactivity is related to the difference in frontier molecular orbitals (FMO) of the metal-oxo and substrate-oxo bonds. Finally, these experimentally related calculations are extended to oxo transfer by sulfite oxidase. The presence of only one dithiolene at the enzyme active site selectively activates the equatorial oxo for transfer, and allows facile structural reorganization during turnover.
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Affiliation(s)
- Yang Ha
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Adam L. Tenderholt
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Richard H. Holm
- Department
of Chemistry and Chemical Biology, Harvard
University, Cambridge, Massachusetts 02138, United States
| | - Britt Hedman
- Stanford
Synchrotron Radiation Lightsource, SLAC, Stanford University, Menlo Park, California 94025, United States
| | - Keith O. Hodgson
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
- Stanford
Synchrotron Radiation Lightsource, SLAC, Stanford University, Menlo Park, California 94025, United States
| | - Edward I. Solomon
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
- Stanford
Synchrotron Radiation Lightsource, SLAC, Stanford University, Menlo Park, California 94025, United States
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Palluccio TD, Rybak-Akimova EV, Majumdar S, Cai X, Chui M, Temprado M, Silvia JS, Cozzolino AF, Tofan D, Velian A, Cummins CC, Captain B, Hoff CD. Thermodynamic and Kinetic Study of Cleavage of the N–O Bond of N-Oxides by a Vanadium(III) Complex: Enhanced Oxygen Atom Transfer Reaction Rates for Adducts of Nitrous Oxide and Mesityl Nitrile Oxide. J Am Chem Soc 2013; 135:11357-72. [DOI: 10.1021/ja405395z] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Taryn D. Palluccio
- Department of Chemistry, Tufts University, 62 Talbot Avenue, Medford, Massachusetts 02155, United States
| | - Elena V. Rybak-Akimova
- Department of Chemistry, Tufts University, 62 Talbot Avenue, Medford, Massachusetts 02155, United States
| | - Subhojit Majumdar
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables,
Florida 33021, United States
| | - Xiaochen Cai
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables,
Florida 33021, United States
| | - Megan Chui
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables,
Florida 33021, United States
| | - Manuel Temprado
- Department of Physical Chemistry, Universidad de Alcalá, Ctra. Madrid-Barcelona Km. 33,600, Madrid 28871, Spain
| | - Jared S. Silvia
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts
Avenue, Cambridge, Massachusetts 02139, United States
| | - Anthony F. Cozzolino
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts
Avenue, Cambridge, Massachusetts 02139, United States
| | - Daniel Tofan
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts
Avenue, Cambridge, Massachusetts 02139, United States
| | - Alexandra Velian
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts
Avenue, Cambridge, Massachusetts 02139, United States
| | - Christopher C. Cummins
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts
Avenue, Cambridge, Massachusetts 02139, United States
| | - Burjor Captain
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables,
Florida 33021, United States
| | - Carl D. Hoff
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables,
Florida 33021, United States
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Holm RH, Solomon EI, Majumdar A, Tenderholt A. Comparative molecular chemistry of molybdenum and tungsten and its relation to hydroxylase and oxotransferase enzymes. Coord Chem Rev 2011. [DOI: 10.1016/j.ccr.2010.10.017] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Lee SC, Holm R. Toward an expanded oxygen atom transfer reactivity scale: Computational investigation of the energetics of oxo transfer reaction couples. Inorganica Chim Acta 2008. [DOI: 10.1016/j.ica.2007.10.047] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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