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Oxygen atom transfer catalysis by dioxidomolybdenum(VI) complexes of pyridyl aminophenolate ligands. Polyhedron 2021. [DOI: 10.1016/j.poly.2021.115234] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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2
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Hossain MK, Köhntopp A, Haukka M, Richmond MG, Lehtonen A, Nordlander E. Cis- and trans molybdenum oxo complexes of a prochiral tetradentate aminophenolate ligand: Synthesis, characterization and oxotransfer activity. Polyhedron 2020. [DOI: 10.1016/j.poly.2019.114312] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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3
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Duffus BR, Schrapers P, Schuth N, Mebs S, Dau H, Leimkühler S, Haumann M. Anion Binding and Oxidative Modification at the Molybdenum Cofactor of Formate Dehydrogenase from Rhodobacter capsulatus Studied by X-ray Absorption Spectroscopy. Inorg Chem 2019; 59:214-225. [PMID: 31814403 DOI: 10.1021/acs.inorgchem.9b01613] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Formate dehydrogenase (FDH) enzymes are versatile catalysts for CO2 conversion. The FDH from Rhodobacter capsulatus contains a molybdenum cofactor with the dithiolene functions of two pyranopterin guanine dinucleotide molecules, a conserved cysteine, and a sulfido group bound at Mo(VI). In this study, we focused on metal oxidation state and coordination changes in response to exposure to O2, inhibitory anions, and redox agents using X-ray absorption spectroscopy (XAS) at the Mo K-edge. Differences in the oxidative modification of the bis-molybdopterin guanine dinucleotide (bis-MGD) cofactor relative to samples prepared aerobically without inhibitor, such as variations in the relative numbers of sulfido (Mo═S) and oxo (Mo═O) bonds, were observed in the presence of azide (N3-) or cyanate (OCN-). Azide provided best protection against O2, resulting in a quantitatively sulfurated cofactor with a displaced cysteine ligand and optimized formate oxidation activity. Replacement of the cysteine ligand by a formate (HCO2-) ligand at the molybdenum in active enzyme is compatible with our XAS data. Cyanide (CN-) inactivated the enzyme by replacing the sulfido ligand at Mo(VI) with an oxo ligand. Evidence that the sulfido group may become protonated upon molybdenum reduction was obtained. Our results emphasize the role of coordination flexibility at the molybdenum center during inhibitory and catalytic processes of FDH enzymes.
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Affiliation(s)
- Benjamin R Duffus
- Institut für Biochemie und Biologie, Molekulare Enzymologie , Universität Potsdam , Karl-Liebknecht Strasse 24-25 , 14476 Potsdam , Germany
| | - Peer Schrapers
- Institut für Experimentalphysik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| | - Nils Schuth
- Institut für Experimentalphysik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| | - Stefan Mebs
- Institut für Experimentalphysik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| | - Holger Dau
- Institut für Experimentalphysik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| | - Silke Leimkühler
- Institut für Biochemie und Biologie, Molekulare Enzymologie , Universität Potsdam , Karl-Liebknecht Strasse 24-25 , 14476 Potsdam , Germany
| | - Michael Haumann
- Institut für Experimentalphysik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
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4
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Chrysochos N, Ahmadi M, Wahlefeld S, Rippers Y, Zebger I, Mroginski MA, Schulzke C. Comparison of molybdenum and rhenium oxo bis-pyrazine-dithiolene complexes - in search of an alternative metal centre for molybdenum cofactor models. Dalton Trans 2019; 48:2701-2714. [PMID: 30720825 DOI: 10.1039/c8dt04237c] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A pair of structurally precise analogues of molybdenum and rhenium complexes, [Et4N]/K2[MoO(prdt)2] and K[ReO(prdt)2] (prdt = pyrazine-2,3-dithiolene), were synthesized. These complexes serve as structural models for the active sites of bacterial molybdenum cofactor containing enzymes. They were comprehensively characterized and investigated by NMR, computationally supported IR and resonance Raman spectroscopy, cyclic voltammetry, mass spectrometry, elemental analysis and single-crystal X-ray diffraction. All compiled data are discussed in the context of comparing chemical and electronic structures and consequences thereof. This study constitutes the first investigation of a potential alternative Moco model system bearing rhenium as the central metal in an identical coordination environment to its molybdenum analogue. Structural evaluation revealed a slightly stronger M[double bond, length as m-dash]O bond in the rhenium complex in accordance with spectroscopic results, i.e. observed bond strengths. Thermodynamic parameters for the redox processes MoIV ↔ MoV and ReIV ↔ ReV were obtained by temperature dependent cyclic voltammetry. In contrast to molybdenum, rhenium loses entropy upon reduction and its redox potential is more temperature sensitive, indicating more significant differences than the respective diagonal relationship between the two metals in the periodic table might suggest and questioning rhenium's suitability as a functional artificial active site metal.
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Affiliation(s)
- Nicolas Chrysochos
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Straße 4, 17487 Greifswald, Germany.
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5
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Reschke S, Mebs S, Sigfridsson-Clauss KGV, Kositzki R, Leimkühler S, Haumann M. Protonation and Sulfido versus Oxo Ligation Changes at the Molybdenum Cofactor in Xanthine Dehydrogenase (XDH) Variants Studied by X-ray Absorption Spectroscopy. Inorg Chem 2017; 56:2165-2176. [DOI: 10.1021/acs.inorgchem.6b02846] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Stefan Reschke
- Institut für
Biochemie und Biologie, Molekulare Enzymologie, Universität Potsdam, 14476 Potsdam, Germany
| | - Stefan Mebs
- Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
| | | | - Ramona Kositzki
- Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Silke Leimkühler
- Institut für
Biochemie und Biologie, Molekulare Enzymologie, Universität Potsdam, 14476 Potsdam, Germany
| | - Michael Haumann
- Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
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6
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Majumdar A. Structural and functional models in molybdenum and tungsten bioinorganic chemistry: description of selected model complexes, present scenario and possible future scopes. Dalton Trans 2015; 43:8990-9003. [PMID: 24798698 DOI: 10.1039/c4dt00631c] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A brief description about some selected model complexes in molybdenum and tungsten bioinorganic chemistry is provided. The synthetic strategies involved and their limitations are discussed. Current status of molybdenum and tungsten bioinorganic modeling chemistry is presented briefly and synthetic problems associated therein are analyzed. Possible future directions which may expand the scope of modeling chemistry are suggested.
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Affiliation(s)
- Amit Majumdar
- Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India.
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7
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Schrapers P, Hartmann T, Kositzki R, Dau H, Reschke S, Schulzke C, Leimkühler S, Haumann M. Sulfido and cysteine ligation changes at the molybdenum cofactor during substrate conversion by formate dehydrogenase (FDH) from Rhodobacter capsulatus. Inorg Chem 2015; 54:3260-71. [PMID: 25803130 DOI: 10.1021/ic502880y] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Formate dehydrogenase (FDH) enzymes are attractive catalysts for potential carbon dioxide conversion applications. The FDH from Rhodobacter capsulatus (RcFDH) binds a bis-molybdopterin-guanine-dinucleotide (bis-MGD) cofactor, facilitating reversible formate (HCOO(-)) to CO2 oxidation. We characterized the molecular structure of the active site of wildtype RcFDH and protein variants using X-ray absorption spectroscopy (XAS) at the Mo K-edge. This approach has revealed concomitant binding of a sulfido ligand (Mo=S) and a conserved cysteine residue (S(Cys386)) to Mo(VI) in the active oxidized molybdenum cofactor (Moco), retention of such a coordination motif at Mo(V) in a chemically reduced enzyme, and replacement of only the S(Cys386) ligand by an oxygen of formate upon Mo(IV) formation. The lack of a Mo=S bond in RcFDH expressed in the absence of FdsC implies specific metal sulfuration by this bis-MGD binding chaperone. This process still functioned in the Cys386Ser variant, showing no Mo-S(Cys386) ligand, but retaining a Mo=S bond. The C386S variant and the protein expressed without FdsC were inactive in formate oxidation, supporting that both Mo-ligands are essential for catalysis. Low-pH inhibition of RcFDH was attributed to protonation at the conserved His387, supported by the enhanced activity of the His387Met variant at low pH, whereas inactive cofactor species showed sulfido-to-oxo group exchange at the Mo ion. Our results support that the sulfido and S(Cys386) ligands at Mo and a hydrogen-bonded network including His387 are crucial for positioning, deprotonation, and oxidation of formate during the reaction cycle of RcFDH.
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Affiliation(s)
- Peer Schrapers
- †Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Tobias Hartmann
- ‡Institut für Biochemie und Biologie, Molekulare Enzymologie, Universität Potsdam, 14476 Potsdam, Germany
| | - Ramona Kositzki
- †Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Holger Dau
- †Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Stefan Reschke
- ‡Institut für Biochemie und Biologie, Molekulare Enzymologie, Universität Potsdam, 14476 Potsdam, Germany
| | - Carola Schulzke
- §Institut für Biochemie, Bioanorganische Chemie, Ernst-Moritz-Arndt-Universität Greifswald, 17487 Greifswald, Germany
| | - Silke Leimkühler
- ‡Institut für Biochemie und Biologie, Molekulare Enzymologie, Universität Potsdam, 14476 Potsdam, Germany
| | - Michael Haumann
- †Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
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8
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Döring A, Fischer C, Schulzke C. Mono-oxo-bis-dithioveratrol-molybdate - in Solution a Model for Arsenite Oxidase and in the Solid State a Coordination Polymer with Unprecedented Binding Motifs. Z Anorg Allg Chem 2013. [DOI: 10.1002/zaac.201300076] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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9
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Arumuganathan T, Volpe M, Harum B, Wurm D, Belaj F, Mösch-Zanetti NC. Unusual Nonoctahedral Geometry with Molybdenum Oxoimido Complexes Containing η2-Pyrazolate Ligands. Inorg Chem 2011; 51:150-6. [DOI: 10.1021/ic201308g] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- T. Arumuganathan
- Institut für Chemie, Anorganische
Chemie, Karl-Franzens-Universität Graz, Stremayrgasse
16, A-8010 Graz, Austria
| | - Manuel Volpe
- Institut für Chemie, Anorganische
Chemie, Karl-Franzens-Universität Graz, Stremayrgasse
16, A-8010 Graz, Austria
| | - Bastian Harum
- Institut für Chemie, Anorganische
Chemie, Karl-Franzens-Universität Graz, Stremayrgasse
16, A-8010 Graz, Austria
| | - Dietmar Wurm
- Institut für Chemie, Anorganische
Chemie, Karl-Franzens-Universität Graz, Stremayrgasse
16, A-8010 Graz, Austria
| | - Ferdinand Belaj
- Institut für Chemie, Anorganische
Chemie, Karl-Franzens-Universität Graz, Stremayrgasse
16, A-8010 Graz, Austria
| | - Nadia C. Mösch-Zanetti
- Institut für Chemie, Anorganische
Chemie, Karl-Franzens-Universität Graz, Stremayrgasse
16, A-8010 Graz, Austria
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10
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Affiliation(s)
- Carola Schulzke
- School of Chemistry, Trinity College Dublin, Dublin 2, Ireland
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11
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Hernandez-Marin E, Ziegler T. Theoretical Study of the Oxidation Reaction and Electron Spin Resonance Parameters Involving Sulfite Oxidase. Inorg Chem 2009; 48:1323-33. [DOI: 10.1021/ic801158t] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Elizabeth Hernandez-Marin
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada T2N 1N4
| | - Tom Ziegler
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada T2N 1N4
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12
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Lyashenko G, Saischek G, Judmaier ME, Volpe M, Baumgartner J, Belaj F, Jancik V, Herbst-Irmer R, Mösch-Zanetti NC. Oxo-molybdenum and oxo-tungsten complexes of Schiff bases relevant to molybdoenzymes. Dalton Trans 2009:5655-65. [DOI: 10.1039/b820629e] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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13
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Pal K, Sarkar S. The Role of Axial Ligation in Nitrate Reductase: A Model Study by DFT Calculations on the Mechanism of Nitrate Reduction. Eur J Inorg Chem 2008. [DOI: 10.1002/ejic.200800514] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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14
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Leopoldini M, Chiodo S, Toscano M, Russo N. Reaction Mechanism of Molybdoenzyme Formate Dehydrogenase. Chemistry 2008; 14:8674-81. [DOI: 10.1002/chem.200800906] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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15
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Lyashenko G, Herbst-Irmer R, Jancik V, Pal A, Mösch-Zanetti NC. Molybdenum oxo and imido complexes of beta-diketiminate ligands: synthesis and structural aspects. Inorg Chem 2008; 47:113-20. [PMID: 18072764 DOI: 10.1021/ic701534a] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Treatment of [MoO2(eta2-Pz)2] (Pz = 3,5-di-tert-butylpyrazolate) with the diketiminate ligand NacNacH (NacNac = CH[C(Me)NAr]2-, Ar = 2,6-Me2C6H3) at 55 degrees C leads under reduction of the metal to the formation of the dimeric molybdenum(V) compound [{MoO2(NacNac)}2] (1). The compound was characterized by spectroscopic means and by X-ray crystal structure analysis. The dimer consists of a [Mo2O4]2+ core with a short Mo-Mo bond (2.5591(5) A) and one coordinated diketiminate ligand on each metal atom. The reaction of [MoO2(eta2-Pz)2] with NacNacH in benzene at room temperature leads to a mixture of 1 and the monomeric molybdenum(VI) compound [MoO2(NacNac)(eta2-Pz)] (2). From such solutions, yellow crystals of 2 suitable for X-ray structural analysis were obtained revealing the coordination of one bidentate NacNac and one eta2-coordinate Pz ligand. This renders the two oxo groups inequivalent. Further high oxidation state molybdenum compounds containing the NacNac ligand were obtained by the reaction of [Mo(NAr)2Cl2(dme)] (Ar = 2,6-Me2C6H3) and [Mo(N-t-Bu)2Cl2(dme)] (dme = dimethoxyethane) with 1 equiv of the potassium salt NacNacK forming [Mo(NAr)2Cl(NacNac)] (3) and [Mo(N-t-Bu)2Cl(NacNac)] (4), respectively, in good yields. The X-ray structure analysis of 3 revealed a penta-coordinate compound where the geometry is best described as trigonal-bipyramidal.
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Affiliation(s)
- Ganna Lyashenko
- Institut für Chemie, Karl-Franzens-Universität Graz, Schubertstrasse 1, A-8010, Graz, Austria
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16
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Nacitarhan C, Kucukatay V, Sadan G, Ozturk OH, Agar A. Effects of sulphite supplementation on vascular responsiveness in sulphite oxidase-deficient rats. Clin Exp Pharmacol Physiol 2007; 35:268-72. [PMID: 17973929 DOI: 10.1111/j.1440-1681.2007.04825.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
1. The aim of the present study was to explore the effect of dietary sulphite supplementation on vascular responsiveness in sulphite oxidase (SO)-deficient rats. 2. Male albino rats were divided into four groups, namely control (n = 8), sulphite-treated (n = 8), SO-deficient (n = 8) and sulphite-treated SO-deficient (n = 8) groups. Sulphite oxidase deficiency was induced by administration of a low-molybdenum diet with concurrent addition of 200 p.p.m. tungsten in the form of sodium tungstate in the drinking water for 9 weeks. Sulphite, in the form of sodium metabisulphite (Na(2)O(5)S(2); 25 mg/kg) was given in the drinking water to sulphite-treated and sulphite-treated SO-deficient groups for the last 6 weeks. The vascular responsiveness of isolated aortic rings to acetylcholine (ACh), sodium nitroprusside (SNP) and histamine was investigated in organ baths. 3. The responsiveness of aortic rings to SNP and histamine did not differ significantly between groups. Conversely, there was a significant decrease in ACh-induced relaxation in aortic rings from the sulphite-treated SO-deficient group compared with the control group (pD(2) 6.2 +/- 0.3 and 7.5 +/- 0.1, respectively; P < 0.05). Incubation of aortic rings in the presence of either l-arginine or superoxide dismutase significantly improved the ACh-induced vasorelaxation in sulphite-treated SO-deficient group (pD(2) 7.2 +/- 0.3 and 7.4 +/- 0.3, respectively). 4. The findings of the present study suggest that the increased production of reactive oxygen species and the resultant increment in l-arginine/nitric oxideconsumption may play a role in the reduced endothelium-dependent vasorelaxation in sulphite-treated SO-deficient rats.
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Affiliation(s)
- Cahit Nacitarhan
- Department of Pharmacology, Faculty of Medicine, Akdeniz University, Antalya, Turkey.
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17
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Chen L, Liu L, Shen H. Studies on Mimic Peroxidase Behaviors of Molybdenum(VI)–Sodium Dodecyl Sulphate Complex for the Determination of Hydrogen Peroxide and Glucose. ANAL LETT 2007. [DOI: 10.1081/al-120029736] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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18
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Pal K, Chaudhury PK, Sarkar S. Structure of the Michaelis Complex and Function of the Catalytic Center in the Reductive Half-Reaction of Computational and Synthetic Models of Sulfite Oxidase. Chem Asian J 2007; 2:956-64. [PMID: 17600788 DOI: 10.1002/asia.200700020] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
By using frontier-molecular-orbital and electrostatic (nucleophilic) interactions as well as relaxed potential-energy surface scans, it is shown that the initial step in the oxygen-atom transfer (OAT) reaction of [Mo(VI)O2-(S2C2Me2)SMe](-1) (1) and [Mo(VI)O2-{(S2C2(CN)2}2]2- (2) with HSO3(-) takes place by oxoanionic binding of the substrate to the Mo(VI) center with the formation of a stable Michaelis complex. The gas-phase and solvent-corrected enthalpy profile with fully optimized minima and transition states for the OAT reaction of 1 and 2 with HSO3(-) showed the release of reaction energy for both complexes. The optimized geometries of 1 and 2 in the respective enzyme-substrate complexes showed a common feature with the participation of hydrogen bonding of the substrate with the axial (spectator) oxo group in the subsequent formation of the six-membered MoO2HOS transition state. The enzyme-substrate complex of 2 shows heptacoordination as proposed earlier, although the trans (to axial oxo)-Mo-S(dithiolene) bond is elongated to 2.948 A.
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Affiliation(s)
- Kuntal Pal
- Department of Chemistry, Indian Institute of Technology, Kanpur, Kanpur 208016, India
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19
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Lyashenko G, Saischek G, Pal A, Herbst-Irmer R, Mösch-Zanetti NC. Molecular oxygen activation by a molybdenum(iv) monooxo bis(β-ketiminato) complex. Chem Commun (Camb) 2007:701-3. [PMID: 17392955 DOI: 10.1039/b617199k] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Molybdenum(IV) monooxo compound that contains bis(beta-ketiminato) ligands activates molecular oxygen forming a molybdenum(VI) monooxo peroxo compound, representing a new entry into molybdenum peroxo derivatives.
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Affiliation(s)
- Ganna Lyashenko
- Institut für Chemie, Karl-Franzens-Universität Graz, Schubertstr. 1, A-8010 Graz, Austria
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20
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Leopoldini M, Russo N, Toscano M, Dulak M, Wesolowski TA. Mechanism of Nitrate Reduction byDesulfovibrio desulfuricans Nitrate Reductase—A Theoretical Investigation. Chemistry 2006; 12:2532-41. [PMID: 16411255 DOI: 10.1002/chem.200500790] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The oxidative half-reaction of oxygen atom transfer from nitrate to an Mo(IV) complex has been investigated at various levels of theory. Two models have been used to simulate the enzyme active site. In the second, more advanced model, additional amino acid residues capable of significantly affecting the catalytic efficiency of the enzyme were included. B3LYP/6-31+G*, ONIOM, and orbital-free embedding approaches have been used to construct the potential energy profile and to qualitatively compare the results of a QM/MM study with those obtained by a full quantum mechanical strategy. The study has confirmed the utility of the orbital-free embedding method in the description of enzymatic processes.
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Affiliation(s)
- Monica Leopoldini
- Dipartimento di Chimica and Centro di Calcolo ad Alte Prestazioni per Elaborazioni Parallele e Distribuite, Centro d'Eccellenza MIUR, Università della Calabria, 87030 Arcavacata di Rende (CS), Italy
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21
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Most K, Hoßbach J, Vidović D, Magull J, Mösch-Zanetti N. Oxygen-Transfer Reactions of Molybdenum- and Tungstendioxo Complexes Containing η2-Pyrazolate Ligands. Adv Synth Catal 2005. [DOI: 10.1002/adsc.200404265] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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22
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Schulzke C. Temperature dependent electrochemical investigations of molybdenum and tungsten oxobisdithiolene complexes. Dalton Trans 2005:713-20. [PMID: 15702182 DOI: 10.1039/b414853c] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
To achieve a better understanding why thermophilic and hyperthermophilic organisms use tungsten instead of molybdenum within the active sites of their molybdopterin dependent oxidases, electrochemical investigations of model complexes for the active sites of enzymes belonging to the DMSO reductase (molybdenum) and the aldehyde oxidoreductase (tungsten) family have been undertaken. Cyclic voltammetry and differential pulse voltammetry of four pairs of molybdenum and tungsten oxobisdithiolene compounds show huge differences in the response of their redox potentials to rising or decreasing temperatures, depending on the substituents at the dithiolene group. The mnt2- compounds (1a, 1b) respond with decreasing redox potentials E(1/2) to rising temperatures whereas all other compounds show positive gradients deltaE/deltaT. In every case the values for the gradients for the tungsten compounds are greater than those for the molybdenum compounds. Six of the investigated compounds are known in the literature and two compounds were newly synthesized. These two new compounds include the pyrane subunit of the native molybdopterin ligand and should therefore be even better models for the active site of the molybdopterin containing enzymes. The molybdenum/tungsten pair with these new ligands shows a remarkably small difference for the redox potentials of the transition M(IV) <--> M(V) of only 30 mV at 25 degrees C and the reversion of the usual order with higher potentials for the molybdenum than the tungsten compound at a temperature of 70 degrees C; a temperature that is in the range where usually tungsten containing enzymes instead of molybdenum containing ones are found.
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Affiliation(s)
- Carola Schulzke
- Institut für Anorganische Chemie, Universität Göttingen, 37077 Göttingen, Germany.
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23
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Thapper A, Behrens A, Fryxelius J, Johansson MH, Prestopino F, Czaun M, Rehder D, Nordlander E. Synthesis and characterization of molybdenum oxo complexes of two tripodal ligands: reactivity studies of a functional model for molybdenum oxotransferases. Dalton Trans 2005:3566-71. [PMID: 16234939 DOI: 10.1039/b505180k] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Reaction of the tetradentate ligand N-(2-hydroxybenzyl)-N,N-bis(2-pyridylmethyl)amine (L-OH) with MoO2Cl2 in methanol in the presence of NaOMe and PF6- results in the formation of [MoO2(L-O)]PF6. Similarly, the reaction of N-(2-mercaptobenzyl)-N,N-bis(2-pyridylmethyl)amine (L-SH) with MoO2(acac)2 leads to the formation of [MoO2(L-S)]+. The dioxo-molybdenum complex [MoO2(L-O)]+ reacts with phosphines in methanol to afford phosphine oxides and an air-sensitive molybdenum complex, tentatively identified as [Mo(IV)O(L-O)(OCH3)]. The latter complex is capable of reducing biological oxygen donors such as DMSO or nitrate, thereby mimicking the activity of DMSO reductase and nitrate reductase. Reaction of [MoO2(L-O)]PF6 with PPh3 in other solvents than methanol leads to the formation of the Mo(V) dimer [(L-O)OMo(micro-O)MoO(L-O)](PF6)2. The crystal structures of [MoO2(L-O)]PF6 and the micro-oxo bridged dimer are presented.
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Affiliation(s)
- Anders Thapper
- Inorganic Chemistry, Center for Chemistry and Chemical Engineering, Lund University, Box 124, SE-221 00, Lund, Sweden
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Chaudhury PK, Nagarajan K, Dubey P, Sarkar S. Symphoria: the success of modeling the active site function of oxo-molybdoenzymes. J Inorg Biochem 2004; 98:1667-77. [PMID: 15522394 DOI: 10.1016/j.jinorgbio.2004.07.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2004] [Revised: 07/05/2004] [Accepted: 07/06/2004] [Indexed: 11/17/2022]
Abstract
The success of modeling the active site function of oxomolybdoenzymes have been claimed generally on the basis of reactivity of the synthetic analogues towards PPh(3) or DMSO (dimethyl sulfoxide). Here it has been shown that the success of modeling the active site function of these enzymes may not be determined by the ability of a model to undergo oxotransfer with PPh(3) or DMSO (except for the modeling of DMSO reductase) and one should adhere to the criteria accepted by the bioinorganic community. A critical evaluation of two of those criteria which requires a synthetic analogue (a) should react with the enzyme substrate (b) should follow the same rate law as does the enzyme, has been presented in this paper. We have shown that the fulfillment of criterion (b) and the inhibition phenomena to that effect both are dictated by symphoria (from sympherin in Greek: the bringing together of reactants into the proper spatial relationship) on the basis of kinetic studies of the reactivity of enzyme substrate the HSO(3)(-) and its analogues (anions of oxyacids of phosphorous) towards a functional model sulfite oxidase [Bu(4)N](2)[Mo(VI)O(2)(mnt)(2)] (mnt(2-)=1,2-dicyanoethylenedithiolate) but with the caveat that the mechanistic inference drawn from such studies may not be the same as in the case of native enzyme. In view of this ambiguity it has been pointed out that the fulfillment of this criterion is not a definitive conclusion towards our understanding of the structure-function relationship of an enzyme and, therefore, the criterion of a 'structural analogue' and 'functional analogue' have been revised subject to an amendment of criterion (a) to include substrate analogues. It has also been shown for the first time on the basis of kinetic studies that the effect of medium can lead to substrate - inhibitor type dualism and hence the effect of medium is also a factor that can play a key role for the success of modeling the active site function of an enzyme. Here we also provide the details of the inhibition mechanisms proposed in our earlier report with an indirect proof to that effect.
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Affiliation(s)
- Pradeep K Chaudhury
- Department of Chemistry, Indian Institute of Technology, Kanpur, Kanpur 208 016, India
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Aguey-Zinsou KF, Bernhardt PV, Kappler U, McEwan AG. Direct electrochemistry of a bacterial sulfite dehydrogenase. J Am Chem Soc 2003; 125:530-5. [PMID: 12517167 DOI: 10.1021/ja028293e] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Sulfite dehydrogenase from Starkeya novella is an alphabeta heterodimer comprising a 40.6 kDa subunit (containing the Mo cofactor) and a smaller 8.8 kDa heme c subunit. The enzyme catalyses the oxidation of sulfite to sulfate with the natural electron acceptor being cytochrome c550. Its catalytic mechanism is thought to resemble that found in eukaryotic sulfite oxidases. Using protein film voltammetry and redox potentiometry, we have identified both Mo- and heme-centered redox responses from the enzyme immobilized on a pyrolytic graphite working electrode: E m,8 (Fe III/II) +177 mV; E m,8 (Mo VI/V) +211 mV and E m,8 (Mo V/IV) -118 mV vs NHE; Upon addition of sulfite to the electrochemical cell a steady-state voltammogram is observed and an apparent Michaelis constant (Km) of 26(1) microM was determined for the enzyme immobilized on the working electrode surface, which is comparable with the value obtained from solution assays.
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26
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Shan X, Ellern A, Espenson JH. Methyloxorhenium(V) complexes with two bidentate ligands: syntheses and reactivity studies. Inorg Chem 2002; 41:7136-42. [PMID: 12495355 DOI: 10.1021/ic025952f] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Four new methyloxorhenium(V) complexes were synthesized: MeReO(PA)(2) (1), MeReO(HQ)(2) (2), MeReO(MQ)(2) (3), and MeReO(diphenylphosphinobenzoate)(2) (4) (in which PAH = 2-picolinic acid, HQH = 8-hydroxyquinoline, and MQH = 8-mercaptoquinoline). Although only one geometric structure has been identified crystallographically for 1, 2, and 3, two isomers of 3 and 4 in solution were detected by NMR spectroscopy. These compounds catalyze the sulfoxidation of thioethers by pyridine N-oxides and sulfoxides. The rate law for the reaction between pyridine N-oxides and thioethers, catalyzed by 1, shows a first-order dependence on the concentrations of pyridine N-oxide and 1. The second-order rate constants of a series of para-substituted pyridine N-oxides fall in the range of 0.27-7.5 L mol(-)(1) s(-)(1). Correlation of these rate constants by the Hammett LFER method gave a large negative reaction constant, rho = -5.2. The next and rapid step does not influence the kinetics, but it could be explored with competition experiments carried out with a pair of methyl aryl sulfides, MeSC(6)H(4)-p-Y. The value of each rate was expressed relative to the reference compound that has Y = H. A Hammett analysis of k(Y)/k(H) gave rho = -1.9. Oxygen-18 labeled 1 was used in a single turnover experiment for 4-picoline N-oxide and dimethyl sulfide. No (18)O-labeled DMSO was found. We suggest that the reaction proceeds by way of two intermediates that were not observed during the reaction. The first intermediate contains an opened PA-chelate ring; this allows the pyridine N-oxide to access the primary coordination sphere of rhenium. The second intermediate is a cis-dioxorhenium(VII) species, which the thioether then attacks. Oxygen-18 experiments were used to show that the two oxygens of this intermediate are not equivalent; only the new oxygen is attacked by, and transferred to, SR(2). Water inhibits the reaction because it hydrolyzes the rhenium(VII) intermediate.
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Affiliation(s)
- Xiaopeng Shan
- Ames Laboratory and the Department of Chemistry, Iowa State University of Science and Technology, 50011, USA
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Thapper A, Deeth RJ, Nordlander E. A density functional study of oxygen atom transfer reactions between biological oxygen atom donors and molybdenum(IV) bis(dithiolene) complexes. Inorg Chem 2002; 41:6695-702. [PMID: 12470064 DOI: 10.1021/ic020385h] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Density functional calculations have been used to investigate oxygen atom transfer reactions from the biological oxygen atom donors trimethylamine N-oxide (Me(3)NO) and dimethyl sulfoxide (DMSO) to the molybdenum(IV) complexes [MoO(mnt)(2)](2-) and [Mo(OCH(3))(mnt)(2)](-) (mnt = maleonitrile-1,2-dithiolate), which may serve as models for mononuclear molybdenum enzymes of the DMSO reductase family. The reaction between [MoO(mnt)(2)](2-) and trimethylamine N-oxide was found to have an activation energy of 72 kJ/mol and proceed via a transition state (TS) with distorted octahedral geometry, where the Me(3)NO is bound through the oxygen to the molybdenum atom and the N-O bond is considerably weakened. The computational modeling of the reactions between dimethyl sulfoxide (DMSO) and [MoO(mnt)(2)](2-) or [Mo(OCH(3))(mnt)(2)](-) indicated that the former is energetically unfavorable while the latter was found to be favorable. The addition of a methyl group to [MoO(mnt)(2)](2-) to form the corresponding des-oxo complex not only lowers the relative energy of the products but also lowers the activation energy. In addition, the reaction with [Mo(OCH(3))(mnt)(2)](-) proceeds via a TS with trigonal prismatic geometry instead of the distorted octahedral TS geometry modeled for the reaction between [MoO(mnt)(2)](2-) and Me(3)NO.
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Affiliation(s)
- Anders Thapper
- Inorganic Chemistry, Chemical Center, Lund University, Box 124, S-221 00 Lund, Sweden
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Beswick CL, Terroba R, Greaney MA, Stiefel EI. [PdS2C2(COOMe)2](6n) (n = 0, -1, -2, -3, -4): hexanuclear homoleptic palladium dithiolene complexes. J Am Chem Soc 2002; 124:9664-5. [PMID: 12175198 DOI: 10.1021/ja026079k] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Reaction of a stoichiometric equivalent of the zinc-dithiolene complex, (tmeda)ZnS2C2(COOMe)2 (tmeda = tetramethylethylenediamine), with (MeCN)2PdCl2 results in a 1:1 homoleptic dithiolene that forms the hexanuclear cluster [PdS2C2(COOMe)2]6 (1). X-ray structure analysis of 1 indicates a Pd6S12 core comprised of six face-centered palladium atoms and 12 edge-centered sulfur atoms situated on an imaginary approximate cube. Complex 1 undergoes four distinct and reversible one-electron redox steps in dichloromethane at -186, -484, -1174, and -1524 mV versus a standard calomel electrode (ferrocenium+/ferrocene redox couple 409 mV). The two-electron reduction product of 1, [Bu4N]2[(PdS2C2(COOMe)2)6] (2), has been chemically isolated and characterized.
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Affiliation(s)
- Colin L Beswick
- ExxonMobil Research and Engineering Company, 1545 Route 22 East, Annandale, New Jersey 08801, USA
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Seymore SB, Brown SN. Synthesis and cleavage reactions of metal-metal-bonded [Mo(2)(S(2)CNR(2))(6)](OTf)(2), a source of the Tris(dithiocarbamato)molybdenum(IV) fragment. Inorg Chem 2001; 40:6676-83. [PMID: 11735478 DOI: 10.1021/ic010673y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Halide abstraction from the chlorotris(dialkyldithiocarbamato)molybdenum(IV) complexes MoCl(S(2)CNR(2))(3) (R = Et, Me) with silver triflate produces the diamagnetic dimeric complexes [Mo(2)(S(2)CNR(2))(6)](OTf)(2) in good yield. The crystallographically determined structure of the diethyldithiocarbamato complex indicates that the dimer consists of two pentagonal bipyramids sharing an axial edge, with a Mo-Mo separation (2.8462(8) A) indicative of a metal-metal bond. A qualitative analysis of the bonding indicates that this bond is of order 2 and consists of one normal sigma bond and one relatively weak "skewed pi" interaction. The dimers [Mo(2)(S(2)CNR(2))(6)](OTf)(2) react with a variety of reagents to give monomeric seven-coordinate complexes, including the new cationic molybdenum(IV) complex [Mo(PMe(2)Ph)(S(2)CNEt(2))(3)](OTf), which has been structurally characterized. Kinetic studies of the reaction of [Mo(2)(S(2)CNEt(2))(6)](OTf)(2) with halides indicate the presence of competing dissociative and associative substitution pathways, although neutral donors may react by different mechanisms.
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Affiliation(s)
- S B Seymore
- Department of Chemistry and Biochemistry, 251 Nieuwland Science Hall, University of Notre Dame, Notre Dame, Indiana 46556-5670, USA
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