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Marques HM. The inorganic chemistry of the cobalt corrinoids - an update. J Inorg Biochem 2023; 242:112154. [PMID: 36871417 DOI: 10.1016/j.jinorgbio.2023.112154] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2023] [Revised: 01/23/2023] [Accepted: 01/26/2023] [Indexed: 02/05/2023]
Abstract
The inorganic chemistry of the cobalt corrinoids, derivatives of vitamin B12, is reviewed, with particular emphasis on equilibrium constants for, and kinetics of, their axial ligand substitution reactions. The role the corrin ligand plays in controlling and modifying the properties of the metal ion is emphasised. Other aspects of the chemistry of these compounds, including their structure, corrinoid complexes with metals other than cobalt, the redox chemistry of the cobalt corrinoids and their chemical redox reactions, and their photochemistry are discussed. Their role as catalysts in non-biological reactions and aspects of their organometallic chemistry are briefly mentioned. Particular mention is made of the role that computational methods - and especially DFT calculations - have played in developing our understanding of the inorganic chemistry of these compounds. A brief overview of the biological chemistry of the B12-dependent enzymes is also given for the reader's convenience.
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Affiliation(s)
- Helder M Marques
- Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg 2050, South Africa.
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2
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Hannibal L, Jacobsen DW. Intracellular processing of vitamin B 12 by MMACHC (CblC). VITAMINS AND HORMONES 2022; 119:275-298. [PMID: 35337623 DOI: 10.1016/bs.vh.2022.02.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Vitamin B12 (cobalamin, Cbl, B12) is a water-soluble micronutrient synthesized exclusively by a group of microorganisms. Human beings are unable to make B12 and thus obtain the vitamin via intake of animal products, fermented plant-based foods or supplements. Vitamin B12 obtained from the diet comprises three major chemical forms, namely hydroxocobalamin (HOCbl), methylcobalamin (MeCbl) and adenosylcobalamin (AdoCbl). The most common form of B12 present in supplements is cyanocobalamin (CNCbl). Yet, these chemical forms cannot be utilized directly as they come, but instead, they undergo chemical processing by the MMACHC protein, also known as CblC. Processing of dietary B12 by CblC involves removal of the upper-axial ligand (beta-ligand) yielding the one-electron reduced intermediate cob(II)alamin. Newly formed cob(II)alamin undergoes trafficking and delivery to the two B12-dependent enzymes, cytosolic methionine synthase (MS) and mitochondrial methylmalonyl-CoA mutase (MUT). The catalytic cycles of MS and MUT incorporate cob(II)alamin as a precursor to regenerate the coenzyme forms MeCbl and AdoCbl, respectively. Mutations and epimutations in the MMACHC gene result in cblC disease, the most common inborn error of B12 metabolism, which manifests with combined homocystinuria and methylmalonic aciduria. Elevation of metabolites homocysteine and methylmalonic acid occurs because the lack of an active CblC blocks formation of the indispensable precursor cob(II)alamin that is necessary to activate MS and MUT. Thus, in patients with cblC disease, vitamin B12 is absorbed and present in circulation in normal to high concentrations, yet, cells are unable to make use of it. Mutations in seemingly unrelated genes that modify MMACHC gene expression also result in clinical phenotypes that resemble cblC disease. We review current knowledge on structural and functional aspects of intracellular processing of vitamin B12 by the versatile protein CblC, its partners and possible regulators.
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Affiliation(s)
- Luciana Hannibal
- Laboratory of Clinical Biochemistry and Metabolism, Department of General Pediatrics, Adolescent Medicine and Neonatology, Faculty of Medicine, Medical Center-University of Freiburg, Freiburg, Germany.
| | - Donald W Jacobsen
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
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3
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Hubbard CD, Chatterjee D, Oszajca M, Polaczek J, Impert O, Chrzanowska M, Katafias A, Puchta R, van Eldik R. Inorganic reaction mechanisms. A personal journey. Dalton Trans 2020; 49:4599-4659. [PMID: 32162632 DOI: 10.1039/c9dt04620h] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
This review covers highlights of the work performed in the van Eldik group on inorganic reaction mechanisms over the past two decades in the form of a personal journey. Topics that are covered include, from NO to HNO chemistry, peroxide activation in model porphyrin and enzymatic systems, the wonder-world of RuIII(edta) chemistry, redox chemistry of Ru(iii) complexes, Ru(ii) polypyridyl complexes and their application, relevant physicochemical properties and reaction mechanisms in ionic liquids, and mechanistic insight from computational chemistry. In each of these sections, typical examples of mechanistic studies are presented in reference to related work reported in the literature.
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Affiliation(s)
- Colin D Hubbard
- Department of Chemistry and Pharmacy, University of Erlangen-Nuremberg, Egerlandstr. 1, 91058 Erlangen, Germany.
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4
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Kenkel I, Franke A, Dürr M, Zahl A, Dücker-Benfer C, Langer J, Filipović MR, Yu M, Puchta R, Fiedler SR, Shores MP, Goldsmith CR, Ivanović-Burmazović I. Switching between Inner- and Outer-Sphere PCET Mechanisms of Small-Molecule Activation: Superoxide Dismutation and Oxygen/Superoxide Reduction Reactivity Deriving from the Same Manganese Complex. J Am Chem Soc 2017; 139:1472-1484. [PMID: 28111938 DOI: 10.1021/jacs.6b08394] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Readily exchangeable water molecules are commonly found in the active sites of oxidoreductases, yet the overwhelming majority of studies on small-molecule mimics of these enzymes entirely ignores the contribution of water to the reactivity. Studies of how these enzymes can continue to function in spite of the presence of highly oxidizing species are likewise limited. The mononuclear MnII complex with the potentially hexadentate ligand N-(2-hydroxy-5-methylbenzyl)-N,N',N'-tris(2-pyridinylmethyl)-1,2-ethanediamine (LOH) was previously found to act as both a H2O2-responsive MRI contrast agent and a mimic of superoxide dismutase (SOD). Here, we studied this complex in aqueous solutions at different pH values in order to determine its (i) acid-base equilibria, (ii) coordination equilibria, (iii) substitution lability and operative mechanisms for water exchange, (iv) redox behavior and ability to participate in proton-coupled electron transfer (PCET) reactions, (v) SOD activity and reductive activity toward both oxygen and superoxide, and (vi) mechanism for its transformation into the binuclear MnII complex with (H)OL-LOH and its hydroxylated derivatives. The conclusions drawn from potentiometric titrations, low-temperature mass spectrometry, temperature- and pressure-dependent 17O NMR spectroscopy, electrochemistry, stopped-flow kinetic analyses, and EPR measurements were supported by the structural characterization and quantum chemical analysis of proposed intermediate species. These comprehensive studies enabled us to determine how transiently bound water molecules impact the rate and mechanism of SOD catalysis. Metal-bound water molecules facilitate the PCET necessary for outer-sphere SOD activity. The absence of the water ligand, conversely, enables the inner-sphere reduction of both superoxide and dioxygen. The LOH complex maintains its SOD activity in the presence of •OH and MnIV-oxo species by channeling these oxidants toward the synthesis of a functionally equivalent binuclear MnII species.
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Affiliation(s)
- Isabell Kenkel
- Department of Chemistry and Pharmacy, University Erlangen-Nuremberg , 91058 Erlangen, Germany
| | - Alicja Franke
- Department of Chemistry and Pharmacy, University Erlangen-Nuremberg , 91058 Erlangen, Germany
| | - Maximilian Dürr
- Department of Chemistry and Pharmacy, University Erlangen-Nuremberg , 91058 Erlangen, Germany
| | - Achim Zahl
- Department of Chemistry and Pharmacy, University Erlangen-Nuremberg , 91058 Erlangen, Germany
| | - Carlos Dücker-Benfer
- Department of Chemistry and Pharmacy, University Erlangen-Nuremberg , 91058 Erlangen, Germany
| | - Jens Langer
- Department of Chemistry and Pharmacy, University Erlangen-Nuremberg , 91058 Erlangen, Germany
| | - Milos R Filipović
- Department of Chemistry and Pharmacy, University Erlangen-Nuremberg , 91058 Erlangen, Germany
| | - Meng Yu
- Department of Chemistry and Biochemistry, Auburn University , Auburn, Alabama 36849, United States
| | - Ralph Puchta
- Department of Chemistry and Pharmacy, University Erlangen-Nuremberg , 91058 Erlangen, Germany
| | - Stephanie R Fiedler
- Department of Chemistry, Colorado State University , Fort Collins, Colorado 80523-1872, United States
| | - Matthew P Shores
- Department of Chemistry, Colorado State University , Fort Collins, Colorado 80523-1872, United States
| | - Christian R Goldsmith
- Department of Chemistry and Biochemistry, Auburn University , Auburn, Alabama 36849, United States
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5
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Surducan M, Makarov SV, Silaghi-Dumitrescu R. Redox and linkage isomerism with ligands relevant to oxidative and nitrosative stress in cobalamin. Polyhedron 2014. [DOI: 10.1016/j.poly.2014.03.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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6
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Theoretical investigation on the vibrational and electronic spectra of three isomeric forms of dicobalt octacarbonyl. J Mol Struct 2014. [DOI: 10.1016/j.molstruc.2013.12.075] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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7
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Soldatova AV, Ibrahim M, Spiro TG. Electronic structure and ligand vibrations in FeNO, CoNO, and FeOO porphyrin adducts. Inorg Chem 2013; 52:7478-86. [PMID: 23763617 PMCID: PMC3766410 DOI: 10.1021/ic400364x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The gaseous ligands, CO, NO, and O2 interact with the Fe ion in heme proteins largely via backbonding of Fe electrons to the π* orbitals of the XO (X = C, N, O) ligands. In these FeXO adducts, the Fe-X stretching frequency varies inversely with the X-O stretching frequency, since increased backbonding strengthens the Fe-X bond while weakening the X-O bond. Inverse frequency correlations have been observed for all three ligands, despite differing electronic and geometric structures, and despite variable composition of the "FeX" vibrational mode, in which Fe-X stretching and Fe-X-O coordinates are mixed for bent FeXO adducts. We report experimental data for 5-coordinate Co(II)(NO) porphyrin adducts (isoelectronic with Fe(II)(OO) adducts), and the results of density functional theory (DFT) modeling for 5-coordinate Fe(II)(NO), Co(II)(NO), and Fe(II)(OO) adducts. Inverse ν(MX)/ν(XO) correlations are obtained computationally, using model porphyrins with graded electron-donating and -withdrawing substituents to modulate the backbonding. Computed slopes agree satisfactorily with experiment, provided nonhybrid functionals are used, which avoid overemphasizing high-spin states. The BP86 functional gives correct ground states, a closed-shell singlet for Co(II)(NO) and an open-shell singlet for the isoelectronic Fe(II)(OO), as corroborated by structural data for Co(II)(NO), and the ν(MX)/ν(XO) slope agreement with experiment for both adducts. However, for Fe(II)(OO) adducts, the computed inverse ν(MX)/ν(XO) correlation applies only to porphyrins with electron-donating and withdrawing substituents of moderate strength. For substituents more donating than -CH3, a direct correlation is obtained, the Fe-O and O-O bonds weakening in concert. This effect is ascribed to the dominance of σ bonding via the in-plane dxz(+dz(2))-π* orbital, when electron-donating substituents raise the d orbital energies sufficiently to render backbonding (dyz-π*) unimportant.
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Affiliation(s)
- Alexandra V. Soldatova
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195
| | | | - Thomas G. Spiro
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195
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8
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Spiro TG, Soldatova AV, Balakrishnan G. CO, NO and O 2 as Vibrational Probes of Heme Protein Interactions. Coord Chem Rev 2013; 257:511-527. [PMID: 23471138 PMCID: PMC3587108 DOI: 10.1016/j.ccr.2012.05.008] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
The gaseous XO molecules (X = C, N or O) bind to the heme prosthetic group of heme proteins, and thereby activate or inhibit key biological processes. These events depend on interactions of the surrounding protein with the FeXO adduct, interactions that can be monitored via the frequencies of the Fe-X and X-O bond stretching modes, νFeX and νXO. The frequencies can be determined by vibrational spectroscopy, especially resonance Raman spectroscopy. Backbonding, the donation of Fe dπ electrons to the XO π* orbitals, is a major bonding feature in all the FeXO adducts. Variations in backbonding produce negative νFeX/νXO correlations, which can be used to gauge electrostatic and H-bonding effects in the protein binding pocket. Backbonding correlations have been established for all the FeXO adducts, using porphyrins with electron donating and withdrawing substituents. However the adducts differ in their response to variations in the nature of the axial ligand, and to specific distal interactions. These variations provide differing vantages for evaluating the nature of protein-heme interactions. We review experimental studies that explore these variations, and DFT computational studies that illuminate the underlying physical mechanisms.
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Affiliation(s)
- Thomas G. Spiro
- Department of Chemistry, University of Washington Box 351700, Seattle, Washington 98195
| | | | - Gurusamy Balakrishnan
- Department of Chemistry, University of Washington Box 351700, Seattle, Washington 98195
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9
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Eisenberg AS, Likhtina IV, Znamenskiy VS, Birke RL. Electronic Spectroscopy and Computational Studies of Glutathionylco(III)balamin. J Phys Chem A 2012; 116:6851-69. [DOI: 10.1021/jp301294x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Azaria S. Eisenberg
- Department of Chemistry, The City
College of New York,
and The Graduate School and University Center, The City University of New York, New York, New York 10031, United
States
| | - Iya V. Likhtina
- Department of Chemistry, The City
College of New York,
and The Graduate School and University Center, The City University of New York, New York, New York 10031, United
States
| | - Vasiliy S. Znamenskiy
- Department of Chemistry, The City
College of New York,
and The Graduate School and University Center, The City University of New York, New York, New York 10031, United
States
| | - Ronald L. Birke
- Department of Chemistry, The City
College of New York,
and The Graduate School and University Center, The City University of New York, New York, New York 10031, United
States
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10
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Pellegrino J, Hübner R, Doctorovich F, Kaim W. Spectroelectrochemical Evidence for the Nitrosyl Redox Siblings NO
+
, NO
.
, and NO
−
Coordinated to a Strongly Electron‐Accepting Fe
II
Porphyrin: DFT Calculations Suggest the Presence of High‐Spin States after Reduction of the Fe
II
–NO
−
Complex. Chemistry 2011; 17:7868-74. [DOI: 10.1002/chem.201003516] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Indexed: 10/18/2022]
Affiliation(s)
- Juan Pellegrino
- Departamento de Química Inorgánica, Analítica, y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. INQUIMAE‐CONICET, Ciudad Universitaria, Pab. 2, C1428EHA Buenos Aires (Argentina), Fax: +54 11 4576‐3341
| | - Ralph Hübner
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70550 Stuttgart (Germany), Fax: (+49) 711 685 64165
| | - Fabio Doctorovich
- Departamento de Química Inorgánica, Analítica, y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. INQUIMAE‐CONICET, Ciudad Universitaria, Pab. 2, C1428EHA Buenos Aires (Argentina), Fax: +54 11 4576‐3341
| | - Wolfgang Kaim
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70550 Stuttgart (Germany), Fax: (+49) 711 685 64165
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11
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Hieringer W, Flechtner K, Kretschmann A, Seufert K, Auwärter W, Barth JV, Görling A, Steinrück HP, Gottfried JM. The Surface Trans Effect: Influence of Axial Ligands on the Surface Chemical Bonds of Adsorbed Metalloporphyrins. J Am Chem Soc 2011; 133:6206-22. [DOI: 10.1021/ja1093502] [Citation(s) in RCA: 186] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Wolfgang Hieringer
- Lehrstuhl für Theoretische Chemie, Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany
| | - Ken Flechtner
- Lehrstuhl für Physikalische Chemie II and Interdisciplinary Center for Molecular Materials (ICMM), Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany
| | - Andreas Kretschmann
- Lehrstuhl für Physikalische Chemie II and Interdisciplinary Center for Molecular Materials (ICMM), Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany
| | - Knud Seufert
- Physik-Department E20, Technische Universität München, James-Franck-Strasse, 85748 Garching, Germany
| | - Willi Auwärter
- Physik-Department E20, Technische Universität München, James-Franck-Strasse, 85748 Garching, Germany
| | - Johannes V. Barth
- Physik-Department E20, Technische Universität München, James-Franck-Strasse, 85748 Garching, Germany
| | - Andreas Görling
- Lehrstuhl für Theoretische Chemie, Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany
| | - Hans-Peter Steinrück
- Lehrstuhl für Physikalische Chemie II and Interdisciplinary Center for Molecular Materials (ICMM), Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany
| | - J. Michael Gottfried
- Lehrstuhl für Physikalische Chemie II and Interdisciplinary Center for Molecular Materials (ICMM), Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany
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12
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Stasicka Z. Transition metal complexes as solar photocatalysts in the environment. ADVANCES IN INORGANIC CHEMISTRY 2011. [DOI: 10.1016/b978-0-12-385904-4.00004-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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13
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Affiliation(s)
- Tatyana E. Shubina
- a Computer-Chemie-Centrum and Interdisciplinary Center for Molecular Materials, Friedrich-Alexander Universität Erlangen-Nürnberg , Nägelsbachstraße 25, 91052 Erlangen, Germany
| | - Timothy Clark
- a Computer-Chemie-Centrum and Interdisciplinary Center for Molecular Materials, Friedrich-Alexander Universität Erlangen-Nürnberg , Nägelsbachstraße 25, 91052 Erlangen, Germany
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14
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Puchta R, Dahlenburg L, Clark T. Why do Cationic Hydridoiridium(III) Complexes with β-Aminophosphane Ligands Favour the Transfer Hydrogenation of Ketones over the Direct “H2-Hydrogenation”?-A Computational Approach. Chemistry 2008; 14:8898-8903. [DOI: 10.1002/chem.200701921] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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16
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Hannibal L, Smith CA, Jacobsen DW, Brasch NE. Nitroxylcob(III)alamin: synthesis and X-ray structural characterization. Angew Chem Int Ed Engl 2007; 46:5140-3. [PMID: 17542034 PMCID: PMC2764306 DOI: 10.1002/anie.200701131] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Luciana Hannibal
- Department of Chemistry and School of Biomedical Sciences, Kent State University, Kent, OH 44242, USA
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17
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Kuta J, Patchkovskii S, Zgierski MZ, Kozlowski PM. Performance of DFT in modeling electronic and structural properties of cobalamins. J Comput Chem 2007; 27:1429-37. [PMID: 16807975 DOI: 10.1002/jcc.20454] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Computational modeling of the enzymatic activity of B12-dependent enzymes requires a detailed understanding of the factors that influence the strength of the Co--C bond and the limits associated with a particular level of theory. To address this issue, a systematic analysis of the electronic and structural properties of coenzyme B12 models has been performed to establish the performance of three different functionals including B3LYP, BP86, and revPBE. In particular the cobalt-carbon bond dissociation energies, axial bond lengths, and selected stretching frequencies have been analyzed in detail. Current analysis shows that widely used B3LYP functional significantly underestimates the strength of the Co--C bond while the nonhybrid BP86 functional produces very consistent results in comparison to experimental data. To explain such different performance of these functionals molecular orbital analysis associated with axial bonds has been performed to show differences in axial bonding provided by hybrid and nonhybrid functionals.
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Affiliation(s)
- Jadwiga Kuta
- Department of Chemistry, University of Louisville, 2320 S. Brook Street, Louisville, Kentucky 40292, USA
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18
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Hannibal L, Smith C, Jacobsen D, Brasch N. Nitroxylcob(III)alamin: Synthesis and X-ray Structural Characterization. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200701131] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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19
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Hubbard CD, van Eldik R. Mechanistic studies of reactions of coordination compounds. Some recent highlights. J COORD CHEM 2007. [DOI: 10.1080/00958970601089200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Colin D. Hubbard
- a Institute for Inorganic Chemistry , University of Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany
| | - Rudi van Eldik
- a Institute for Inorganic Chemistry , University of Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany
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20
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Franke A, Roncaroli F, van Eldik R. Mechanistic Studies on the Activation of NO by Iron and Cobalt Complexes. Eur J Inorg Chem 2007. [DOI: 10.1002/ejic.200600921] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Alicja Franke
- Institute for Inorganic Chemistry, University of Erlangen‐Nürnberg, Egerlandstr. 1, 91058 Erlangen, Germany
| | - Federico Roncaroli
- Institute for Inorganic Chemistry, University of Erlangen‐Nürnberg, Egerlandstr. 1, 91058 Erlangen, Germany
- Department of Inorganic, Analytical and Physical Chemistry, INQUIMAE, Faculty of Exact and Natural Sciences, University of Buenos Aires, C1428EHA Buenos Aires, Argentina
| | - Rudi van Eldik
- Institute for Inorganic Chemistry, University of Erlangen‐Nürnberg, Egerlandstr. 1, 91058 Erlangen, Germany
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21
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Roncaroli F, Shubina TE, Clark T, van Eldik R. Nitrite Impurities Are Responsible for the Reaction Observed between Vitamin B12 and Nitric Oxide in Acidic Aqueous Solution. Inorg Chem 2006; 45:7869-76. [PMID: 16961380 DOI: 10.1021/ic061151r] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The reaction between aquacobalamin, Cbl(H2O), and NO was studied at low pH. As previously reported, the final product of the reaction is the same as that obtained in the reaction of NO and reduced Cbl(H2O), viz. Cbl(NO-). Nevertheless, this reductive nitrosylation is preceded by a faster reaction (accompanied by small absorbance changes) that depends on the HNO2 concentration but not on the NO concentration. Kinetic and UV-vis spectroscopic data show that Cbl(NO2-) is generated during this reaction. Spectroscopic data show that the dimethylbenzimidazole group trans to the NO2- ligand is protonated and partially dechelated at pH 1, by which a reaction with NO is induced. DFT calculations were performed to compare the ability of NO and NO2- to bind to cobalamin and their influence on the stability of the dimethylbenzimidazole group. The reductive nitrosylation reaction shows a quadratic dependence on the HNO2 concentration and an inverse dependence on the NO concentration. It also strongly depends on pH and is no longer observed at pH > 4. On the basis of earlier work performed on a series of Co(III) porphyrins, a mechanism is proposed that can quantitatively account for the HNO2 and NO dependencies. The reductive nitrosylation reaction is practically dominated by a back reaction, i.e., the reaction between Cbl(NO-) and HNO2, which accounts for the strange NO and HNO2 concentration dependencies observed.
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Affiliation(s)
- Federico Roncaroli
- Institute for Inorganic Chemistry, University of Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany
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22
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Jee JE, van Eldik R. Mechanistic Studies on the Nitrite-Catalyzed Reductive Nitrosylation of Highly Charged Anionic and Cationic FeIII Porphyrin Complexes. Inorg Chem 2006; 45:6523-34. [PMID: 16878967 DOI: 10.1021/ic0603104] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The nitrosyl complexes formed during the binding of NO to the (Pn)FeIII(H2O)2 (n = 8+ and 8-) complexes, viz., (P8-)FeII(H2O)(NO+) and (P8+)FeII(H2O)(NO+), undergo subsequent reductive nitrosylation reactions that were found to be catalyzed by nitrite, which was also produced during the reaction. The effect of the nitrite concentration, pH, temperature, and pressure on the nitrite-catalyzed reductive nitrosylation process was studied in detail for (P8-)FeIII(H2O)2, (P8+)FeIII(H2O)2, and (P8+)FeIII(OH)(H2O), from which rate and activation parameters were obtained. On the basis of these data, we propose mechanistic pathways for the studied reactions. The available results favor the operation of an innersphere electron-transfer process between nitrite and coordinated NO(+). By way of comparison, the cationic porphyrin complex (P8+)FeIII(L)2 (L = H2O or OH-) was found to react with NO2(-) to yield the nitrite adduct (P8+)FeIII(L)(NO2)(-)). A detailed kinetic studied revealed that nitrite binds to (P8+)FeIII(H2O)2 according to a dissociative mechanism, whereas nitrite binding to (P8+)FeIII(OH)(H2O) at higher pH follows an associative mechanism, similar to that reported for the binding of NO to these complexes.
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Affiliation(s)
- Joo-Eun Jee
- Institute for Inorganic Chemistry, University of Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany
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Spataru T, Birke RL. Carbon−Cobalt Bond Distance and Bond Cleavage in One-Electron Reduced Methylcobalamin: A Failure of the Conventional DFT Method. J Phys Chem A 2006; 110:8599-604. [PMID: 16836419 DOI: 10.1021/jp062741d] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Geometry optimizations at the HF, B3LYP, and CASSCF levels of electronic structure theory have been performed for methylcobalamin (MeCbl) model compounds in both the Co(III) (MeCbl(III)) and Co(II) (MeCbl(II)) formal oxidation states. Since the HOMO-LUMO and C-Co sigma-sigma MO gaps are significantly smaller in the MeCbl(II) compounds compared with MeCbl(III), a pseudo-Jahn Teller effect is possible. CASSCF calculations show that there is strong coupling between C-Co sigma-sigma MOs for the MeCbl(II) models leading to strong state mixing with significant total charge density transfer (approximately 0.4 e-), mainly from the C-Co sigma MO to C-Co sigma MO (approximately 0.3 e-). CASSCF(9:7) calculations show that the strong state mixing leads to an increase in the C-Co bond length for MeCbl(II) model compounds from 1.969 A (DFT and HF calculations) to 2.164 A in the base-on MeCbl(II) model and from 1.938 A to 2.144 A in the base-off MeCbl(II) model. Concomitantly, the Co-N axial bond length increases from 2.121 A (DFT) to 2.344 A in the CASSCF calculation. This coupling interaction between states can be used to explain the much lower Co-C bond dissociation enthalpy and much faster bond cleavage rate for the one-electron reduced methylcobalamin radical anion compared to MeCbl(III). It may also be important for axial bond distances in other Co(II) compounds.
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24
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Roncaroli F, van Eldik R. Mechanistic Analysis of Reductive Nitrosylation on Water-Soluble Cobalt(III)-Porphyrins. J Am Chem Soc 2006; 128:8042-53. [PMID: 16771520 DOI: 10.1021/ja0549906] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The reactions of NO and/or NO2- with three water-soluble cobalt porphyrins [Co(III)(P)(H2O)2]n, where P = TPPS, TCPP, and TMPyP, were studied in detail. At pH < 3, the reaction with NO proceeds through a single reaction step. From the kinetic data and activation parameters, the [Co(III)(P)(NO)(H2O)]n complex is proposed to be the primary product of the reaction with NO. This complex reacts further with a second NO molecule through an inner-sphere electron-transfer reaction to generate the final product, [Co(III)(P)(NO-)](n-1). At pH > 3, although a single reaction step is also observed, a systematic study as a function of the NO and NO2- concentrations revealed that two reaction steps are operative. In the first, NO2- and NO compete to substitute coordinated water in [Co(III)(P)(H2O)2]n to yield [Co(III)(P)(NO)(H2O)]n and [Co(III)(P)(NO2-)(H2O)](n-1) as the primary reaction products. Only the nitrite complex could be detected and no final product formation was observed during the reaction. It is proposed that [Co(III)(P)(NO)(H2O)]n rapidly reacts with NO2- to form the nitrite complex, which in the second reaction step reacts with another NO molecule to generate the final product through an inner-sphere electron-transfer reaction. The reported results are relevant for the interaction of vitamin B(12a) with NO and NO2-.
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Affiliation(s)
- Federico Roncaroli
- Institute for Inorganic Chemistry, University of Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany
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25
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Carter SM, Lee J, Hixson CA, Powell DR, Wheeler RA, Shaw MJ, Richter-Addo GB. Fiber-optic infrared reflectance spectroelectrochemical studies of osmium and ruthenium nitrosyl porphyrins containing alkoxide and thiolate ligands. Dalton Trans 2006:1338-46. [PMID: 16505913 DOI: 10.1039/b510717b] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have examined the redox behavior of the osmium and ruthenium compounds (OEP)M(NO)(OEt) and (OEP)M(NO)(SEt) (OEP = octaethylporphyrinato dianion; M = Os, Ru) by cyclic voltammetry and infrared spectroelectrochemistry. The compound (OEP)Os(NO)(OEt) undergoes a single reversible oxidation process in dichloromethane. In contrast, the thiolate compound (OEP)Os(NO)(SEt) undergoes a net irreversible oxidation resulting in formal loss of the SEt ligand. Extended Hückel calculations on crystal structures of these two compounds provide insight into the nature of their HOMOs. In the case of the alkoxide compound, the HOMO is largely metal centered, with 70% of the charge located in the metal's orbital and approximately 25% on the porphyrin ring. However, the HOMO of the thiolate compound consists of a pi bonding interaction between the metal dxz orbital and the px orbital on the sulfur, and a pi antibonding interaction between the metal d orbital and a pi* orbital on NO. The redox behavior of the Ru analogues have been determined, and are compared with those of the Os compounds.
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Affiliation(s)
- Shawn M Carter
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK 73019, USA
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26
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Dölker N, Morreale A, Maseras F. Computational study on the difference between the Co–C bond dissociation energy in methylcobalamin and adenosylcobalamin. J Biol Inorg Chem 2005; 10:509-17. [PMID: 15986217 DOI: 10.1007/s00775-005-0662-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2004] [Accepted: 05/16/2005] [Indexed: 10/25/2022]
Abstract
The bond dissociation energies of the Co-C bonds in the cobalamin cofactors methylcobalamin and adenosylcobalamin were calculated using the hybrid quantum mechanics/molecular mechanics method IMOMM (integrated molecular orbital and molecular mechanics). Calculations were performed on models of differing complexities as well as on the full systems. We investigated the origin of the different experimental values for the Co-C bond dissociation energies in methylcobalamin and adenosylcobalamin, and have provided an explanation for the difficulties encountered when we attempt to reproduce this difference in quantum chemistry. Additional calculations have been performed using the Miertus-Scrocco-Tomasi method in order to estimate the influence of solvent effects on the homolytic Co-C bond cleavage. Introduction of these solvation effects is shown to be necessary for the correct reproduction of experimental trends in bond dissociation energies in solution, which consequently have no direct correlation with dissociation processes in the enzyme.
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Affiliation(s)
- Nicole Dölker
- Unitat de Química Física, Edifici C.n, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia, Spain.
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