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Shichijo K, Kametani Y, Shiota Y, Yoshizawa K, Fujitsuka M, Shimakoshi H. Effect of Macrocycles on the Photochemical and Electrochemical Properties of Cobalt-Dehydrocorrin Complex: Formation and Investigation of Co(I) Species. Inorg Chem 2023; 62:11785-11795. [PMID: 37307067 DOI: 10.1021/acs.inorgchem.3c00882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Co(II)-pyrocobester (P-Co(II)), a dehydrocorrin complex, was semisynthesized from vitamin B12 (cyanocobalamin), and its photochemical and electrochemical properties were investigated and compared to those of the cobester (C-Co(II)), the cobalt-corrin complex. The UV-vis absorptions of P-Co(II) in CH2Cl2, ascribed to the π-π* transition, were red-shifted compared to those of C-Co(II) due to the π-expansion of the macrocycle in the pyrocobester. The reversible redox couple of P-Co(II) was observed at E1/2 = -0.30 V vs Ag/AgCl in CH3CN, which was assigned to the Co(II)/Co(I) redox couple by UV-vis, ESR, and molecular orbital analysis. This redox couple was positively shifted by 0.28 V compared to that of C-Co(II). This is caused by the high electronegativity of the dehydrocorrin macrocycle, which was estimated by DFT calculations for the free-base ligands. The reactivity of the Co(I)-pyrocobester (P-Co(I)) was evaluated by the reaction with methyl iodide in CV and UV-vis to form a photosensitive Co(III)-CH3 complex (P-Co(III)-CH3). The properties of the excited state of P-Co(I), *Co(I), were also investigated by femtosecond transient absorption (TA) spectroscopy. The lifetime of *Co(I) was estimated to be 29 ps from the kinetic trace at 587 nm. The lifetime of *Co(I) became shorter in the presence of Ar-X, such as iodobenzonitrile (1a), bromobenzonitrile (1b), and chlorobenzonitrile (1c), and the rate constants of electron transfer (ET) between the *Co(I) and Ar-X were determined to be 2.9 × 1011 M-1 s-1, 4.9 × 1010 M-1 s-1, and 1.0 × 1010 M-1 s-1 for 1a, 1b, and 1c, respectively.
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Affiliation(s)
- Keita Shichijo
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, Nishi-ku, Motooka, 744, Fukuoka 819-0395, Japan
| | - Yohei Kametani
- Institute for Materials Chemistry and Engineering, Kyushu University, Nishi-ku, Motooka, 744, Fukuoka 819-0395, Japan
| | - Yoshihito Shiota
- Institute for Materials Chemistry and Engineering, Kyushu University, Nishi-ku, Motooka, 744, Fukuoka 819-0395, Japan
| | - Kazunari Yoshizawa
- Institute for Materials Chemistry and Engineering, Kyushu University, Nishi-ku, Motooka, 744, Fukuoka 819-0395, Japan
| | - Mamoru Fujitsuka
- SANKEN (The Institute of Scientific and Industrial Research), Osaka University, Osaka 567-0047, Japan
| | - Hisashi Shimakoshi
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, Nishi-ku, Motooka, 744, Fukuoka 819-0395, Japan
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2
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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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3
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Esser AJ, Mukherjee S, Dereven‘kov IA, Makarov SV, Jacobsen DW, Spiekerkoetter U, Hannibal L. Versatile Enzymology and Heterogeneous Phenotypes in Cobalamin Complementation Type C Disease. iScience 2022; 25:104981. [PMID: 36105582 PMCID: PMC9464900 DOI: 10.1016/j.isci.2022.104981] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Nutritional deficiency and genetic errors that impair the transport, absorption, and utilization of vitamin B12 (B12) lead to hematological and neurological manifestations. The cblC disease (cobalamin complementation type C) is an autosomal recessive disorder caused by mutations and epi-mutations in the MMACHC gene and the most common inborn error of B12 metabolism. Pathogenic mutations in MMACHC disrupt enzymatic processing of B12, an indispensable step before micronutrient utilization by the two B12-dependent enzymes methionine synthase (MS) and methylmalonyl-CoA mutase (MUT). As a result, patients with cblC disease exhibit plasma elevation of homocysteine (Hcy, substrate of MS) and methylmalonic acid (MMA, degradation product of methylmalonyl-CoA, substrate of MUT). The cblC disorder manifests early in childhood or in late adulthood with heterogeneous multi-organ involvement. This review covers current knowledge on the cblC disease, structure–function relationships of the MMACHC protein, the genotypic and phenotypic spectra in humans, experimental disease models, and promising therapies.
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Zhang S, Adrian L, Schüürmann G. Outer-sphere electron transfer does not underpin B 12-dependent olefinic reductive dehalogenation in anaerobes. Phys Chem Chem Phys 2021; 23:27520-27524. [PMID: 34874373 DOI: 10.1039/d1cp04632b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Anaerobic microbial B12-dependent reductive dehalogenation may pave a way to remediate soil, sediment, and underground water contaminated with halogenated olefins. The chemical reaction is initiated by electron transfer (ET) from supernucleophilic cob(I)alamin (B12s). However, the inherent mechanism as outer-sphere or inner-sphere route is still under debate. To clarify the possibility of an outer-sphere pathway, we calculated free energy barriers of the initial steps of all outer-sphere ET routes by Marcus theory employing density functional theory (DFT). For 18 fluorinated, chlorinated, and brominated ethenes as representative olefins, 164 of 165 reactions with free energy barriers larger than 20 kcal mol-1 are not feasible under physiological dehalogenase conditions. Moreover, electronic structure analysis of perbromoethene with an outer-sphere free energy barrier of 18.2 kcal mol-1 reveals no ET initiation down to Co⋯Br and Co⋯C distances of 3.15 Å. The results demonstrate that the B12-catalyzed reductive dechlorination of olefins in microbes should proceed through an inner-sphere ET pathway.
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Affiliation(s)
- Shangwei Zhang
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-Sen University, Guangzhou 510006, China.,UFZ Department of Ecological Chemistry, Helmholtz Centre for Environmental Research, Permoserstraße 15, Leipzig 04318, Germany.
| | - Lorenz Adrian
- UFZ Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research, Permoserstraße 15, 04318 Leipzig, Germany.,Chair of Geobiotechnology, Technische Universität Berlin, Ackerstraße 76, 13355 Berlin, Germany
| | - Gerrit Schüürmann
- UFZ Department of Ecological Chemistry, Helmholtz Centre for Environmental Research, Permoserstraße 15, Leipzig 04318, Germany. .,Technical University Bergakademie Freiberg, Institute of Organic Chemistry, Leipziger Straße 29, 09596 Freiberg, Germany.
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5
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Neumann F, Dobbek H. ATP Binding and a Second Reduction Enables a Conformationally Gated Uphill Electron Transfer. ACS Catal 2021. [DOI: 10.1021/acscatal.1c01038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Felix Neumann
- Institut für Biologie, Strukturbiologie/Biochemie, Humboldt-Universität zu Berlin, Unter den Linden 6, 10099 Berlin, Germany
| | - Holger Dobbek
- Institut für Biologie, Strukturbiologie/Biochemie, Humboldt-Universität zu Berlin, Unter den Linden 6, 10099 Berlin, Germany
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Sitek P, Chmielowska A, Jaworska M, Lodowski P, Szczepańska M. Theoretical study of cobalt and nickel complexes involved in methyl transfer reactions: structures, redox potentials and methyl binding energies. Struct Chem 2019. [DOI: 10.1007/s11224-019-01384-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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7
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Elucidating the mechanism of cob(I)alamin mediated methylation reactions by alkyl halides: SN2 or radical mechanism? J Catal 2019. [DOI: 10.1016/j.jcat.2019.06.036] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Ji L, Wang C, Ji S, Kepp KP, Paneth P. Mechanism of Cobalamin-Mediated Reductive Dehalogenation of Chloroethylenes. ACS Catal 2017. [DOI: 10.1021/acscatal.7b00540] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Li Ji
- College
of Environmental and Resource Sciences, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China
| | - Chenchen Wang
- College
of Environmental and Resource Sciences, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China
| | - Shujing Ji
- College
of Environmental and Resource Sciences, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China
| | - Kasper P. Kepp
- DTU
Chemistry, Technical University of Denmark, Building 206, Kgs. Lyngby DK-2800, Denmark
| | - Piotr Paneth
- Institute
of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924 Lodz, Poland
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9
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Electronic and structural properties of Cob(I)alamin: Ramifications for B 12 -dependent processes. Coord Chem Rev 2017. [DOI: 10.1016/j.ccr.2016.11.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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10
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Johnston RC, Zhou J, Smith JC, Parks JM. Toward Quantitatively Accurate Calculation of the Redox-Associated Acid-Base and Ligand Binding Equilibria of Aquacobalamin. J Phys Chem B 2016; 120:7307-18. [PMID: 27391132 DOI: 10.1021/acs.jpcb.6b02701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Redox processes in complex transition metal-containing species are often intimately associated with changes in ligand protonation states and metal coordination number. A major challenge is therefore to develop consistent computational approaches for computing pH-dependent redox and ligand dissociation properties of organometallic species. Reduction of the Co center in the vitamin B12 derivative aquacobalamin can be accompanied by ligand dissociation, protonation, or both, making these properties difficult to compute accurately. We examine this challenge here by using density functional theory and continuum solvation to compute Co-ligand binding equilibrium constants (Kon/off), pKas, and reduction potentials for models of aquacobalamin in aqueous solution. We consider two models for cobalamin ligand coordination: the first follows the hexa, penta, tetra coordination scheme for Co(III), Co(II), and Co(I) species, respectively, and the second model features saturation of each vacant axial coordination site on Co(II) and Co(I) species with a single, explicit water molecule to maintain six directly interacting ligands or water molecules in each oxidation state. Comparing these two coordination schemes in combination with five dispersion-corrected density functionals, we find that the accuracy of the computed properties is largely independent of the scheme used, but including only a continuum representation of the solvent yields marginally better results than saturating the first solvation shell around Co throughout. PBE performs best, displaying balanced accuracy and superior performance overall, with RMS errors of 80 mV for seven reduction potentials, 2.0 log units for five pKas and 2.3 log units for two log Kon/off values for the aquacobalamin system. Furthermore, we find that the BP86 functional commonly used in corrinoid studies suffers from erratic behavior and inaccurate descriptions of Co-axial ligand binding, leading to substantial errors in predicted pKas and Kon/off values. These findings demonstrate the effectiveness of the present approach for computing electrochemical and thermodynamic properties of a complex transition metal-containing cofactor.
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Affiliation(s)
- Ryne C Johnston
- UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory , 1 Bethel Valley Road, Oak Ridge, Tennessee 37831-6309, United States
| | | | | | - Jerry M Parks
- UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory , 1 Bethel Valley Road, Oak Ridge, Tennessee 37831-6309, United States
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12
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Garabato BD, Kumar N, Lodowski P, Jaworska M, Kozlowski PM. Electronically excited states of cob(ii)alamin: insights from CASSCF/XMCQDPT2 and TD-DFT calculations. Phys Chem Chem Phys 2016; 18:4513-26. [DOI: 10.1039/c5cp06439b] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The low-lying excited states of cob(ii)alamin were investigated using time-dependent density functional theory (TD-DFT), and multiconfigurational CASSCF/XMCQDPT2 methodology, to help understand their role in B12-mediated reactions.
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Affiliation(s)
| | - Neeraj Kumar
- Department of Chemistry
- University of Louisville
- Louisville
- USA
- Pacific Northwest National Laboratory
| | - Piotr Lodowski
- Department of Theoretical Chemistry
- Institute of Chemistry
- University of Silesia
- PL-40 006 Katowice
- Poland
| | - Maria Jaworska
- Department of Theoretical Chemistry
- Institute of Chemistry
- University of Silesia
- PL-40 006 Katowice
- Poland
| | - Pawel M. Kozlowski
- Department of Chemistry
- University of Louisville
- Louisville
- USA
- Visiting Professor at the Department of Food Sciences
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13
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Cooper M, Wagner A, Wondrousch D, Sonntag F, Sonnabend A, Brehm M, Schüürmann G, Adrian L. Anaerobic microbial transformation of halogenated aromatics and fate prediction using electron density modeling. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:6018-28. [PMID: 25909816 DOI: 10.1021/acs.est.5b00303] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Halogenated homo- and heterocyclic aromatics including disinfectants, pesticides and pharmaceuticals raise concern as persistent and toxic contaminants with often unknown fate. Remediation strategies and natural attenuation in anaerobic environments often build on microbial reductive dehalogenation. Here we describe the transformation of halogenated anilines, benzonitriles, phenols, methoxylated, or hydroxylated benzoic acids, pyridines, thiophenes, furoic acids, and benzenes by Dehalococcoides mccartyi strain CBDB1 and environmental fate modeling of the dehalogenation pathways. The compounds were chosen based on structural considerations to investigate the influence of functional groups present in a multitude of commercially used halogenated aromatics. Experimentally obtained growth yields were 0.1 to 5 × 10(14) cells mol(-1) of halogen released (corresponding to 0.3-15.3 g protein mol(-1) halogen), and specific enzyme activities ranged from 4.5 to 87.4 nkat mg(-1) protein. Chlorinated electron-poor pyridines were not dechlorinated in contrast to electron-rich thiophenes. Three different partial charge models demonstrated that the regioselective removal of halogens is governed by the least negative partial charge of the halogen. Microbial reaction pathways combined with computational chemistry and pertinent literature findings on Co(I) chemistry suggest that halide expulsion during reductive dehalogenation is initiated through single electron transfer from B12Co(I) to the apical halogen site.
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Affiliation(s)
- Myriel Cooper
- †Helmholtz-Zentrum für Umweltforschung - UFZ, Department Isotope Biogeochemistry, Permoserstrasse15, 04318 Leipzig, Germany
| | - Anke Wagner
- ‡Technische Universität Berlin, Fachgebiet Applied Biochemistry, Gustav-Meyer-Allee 25, 13355 Berlin, Germany
| | - Dominik Wondrousch
- §Helmholtz-Zentrum für Umweltforschung - UFZ, Department Ecological Chemistry, Permoserstrasse 15, 04318 Leipzig, Germany
- ∥Technische Universität Bergakademie Freiberg, Institute for Organic Chemistry, Leipziger Strasse 29, 09596 Freiberg, Germany
| | - Frank Sonntag
- ‡Technische Universität Berlin, Fachgebiet Applied Biochemistry, Gustav-Meyer-Allee 25, 13355 Berlin, Germany
| | - Andrei Sonnabend
- ‡Technische Universität Berlin, Fachgebiet Applied Biochemistry, Gustav-Meyer-Allee 25, 13355 Berlin, Germany
| | - Martin Brehm
- §Helmholtz-Zentrum für Umweltforschung - UFZ, Department Ecological Chemistry, Permoserstrasse 15, 04318 Leipzig, Germany
| | - Gerrit Schüürmann
- §Helmholtz-Zentrum für Umweltforschung - UFZ, Department Ecological Chemistry, Permoserstrasse 15, 04318 Leipzig, Germany
- ∥Technische Universität Bergakademie Freiberg, Institute for Organic Chemistry, Leipziger Strasse 29, 09596 Freiberg, Germany
| | - Lorenz Adrian
- †Helmholtz-Zentrum für Umweltforschung - UFZ, Department Isotope Biogeochemistry, Permoserstrasse15, 04318 Leipzig, Germany
- ‡Technische Universität Berlin, Fachgebiet Applied Biochemistry, Gustav-Meyer-Allee 25, 13355 Berlin, Germany
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14
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Lodowski P, Jaworska M, Garabato BD, Kozlowski PM. Mechanism of Co–C Bond Photolysis in Methylcobalamin: Influence of Axial Base. J Phys Chem A 2015; 119:3913-28. [DOI: 10.1021/jp5120674] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Piotr Lodowski
- Department
of Theoretical Chemistry, Institute of Chemistry, University of Silesia, Szkolna 9, PL-40 006 Katowice, Poland
| | - Maria Jaworska
- Department
of Theoretical Chemistry, Institute of Chemistry, University of Silesia, Szkolna 9, PL-40 006 Katowice, Poland
| | - Brady D. Garabato
- Department
of Chemistry, University of Louisville, Louisville, Kentucky 40292, United States
| | - Pawel M. Kozlowski
- Department
of Chemistry, University of Louisville, Louisville, Kentucky 40292, United States
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15
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Dereven'kov IA, Salnikov DS, Makarov SV, Boss GR, Koifman OI. Kinetics and mechanism of oxidation of super-reduced cobalamin and cobinamide species by thiosulfate, sulfite and dithionite. Dalton Trans 2014; 42:15307-16. [PMID: 23999614 DOI: 10.1039/c3dt51714d] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
We studied the kinetics of reactions of cob(I)alamin and cob(I)inamide with thiosulfate, sulfite, and dithionite by UV-Visible (UV-Vis) and stopped-flow spectroscopy. We found that the two Co(I) species were oxidized by these sulfur-containing compounds to Co(II) forms: oxidation by excess thiosulfate leads to penta-coordinate complexes and oxidation by excess sulfite or dithionite leads to hexa-coordinate Co(II)-SO2(-) complexes. The net scheme involves transfer of three electrons in the case of oxidation by thiosulfate and one electron for oxidation by sulfite and dithionite. On the basis of kinetic data, the nature of the reactive oxidants was suggested, i.e., HS2O3(-) (for oxidation by thiosulfate), S2O5(2-), HSO3(-), and aquated SO2 (for oxidation by sulfite), and S2O4(2-) and SO2(-) (for oxidation by dithionite). No difference was observed in kinetics with cob(i)alamin or cob(i)inamide as reductants.
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Affiliation(s)
- Ilia A Dereven'kov
- State University of Chemistry and Technology, Sheremetevskiy str. 7, 153000 Ivanovo, Russia.
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16
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Demissie TB, Repisky M, Liu H, Ruud K, Kozlowski PM. Cob(II)alamin: Relativistic DFT Analysis of the EPR Parameters. J Chem Theory Comput 2014; 10:2125-36. [DOI: 10.1021/ct400769t] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Taye B. Demissie
- Centre for Theoretical and Computational
Chemistry, Department of Chemistry, UiT The Arctic University of Norway, 9037 Tromsø, Norway
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Michal Repisky
- Centre for Theoretical and Computational
Chemistry, Department of Chemistry, UiT The Arctic University of Norway, 9037 Tromsø, Norway
| | - Hui Liu
- Department of Chemistry, University of Louisville, 2320 South Brook Street, Louisville, Kentucky 40292, United States
| | - Kenneth Ruud
- Centre for Theoretical and Computational
Chemistry, Department of Chemistry, UiT The Arctic University of Norway, 9037 Tromsø, Norway
| | - Pawel M. Kozlowski
- Department of Chemistry, University of Louisville, 2320 South Brook Street, Louisville, Kentucky 40292, United States
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Kornobis K, Ruud K, Kozlowski PM. Cob(I)alamin: insight into the nature of electronically excited states elucidated via quantum chemical computations and analysis of absorption, CD and MCD data. J Phys Chem A 2013; 117:863-76. [PMID: 23281629 DOI: 10.1021/jp310446c] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The nature of electronically excited states of the super-reduced form of vitamin B(12) (i.e., cob(I)alamin or B(12s)), a ubiquitous B(12) intermediate, was investigated by performing quantum-chemical calculations within the time-dependent density functional theory (TD-DFT) framework and by establishing their correspondence to experimental data. Using response theory, the electronic absorption (Abs), circular dichroism (CD) and magnetic CD (MCD) spectra of cob(I)alamin were simulated and directly compared with experiment. Several issues have been taken into considerations while performing the TD-DFT calculations, such as strong dependence on the applied exchange-correlation (XC) functional or structural simplification imposed on the cob(I)alamin. In addition, the low-lying transitions were also validated by performing CASSCF/MC-XQDPT2 calculations. By comparing computational results with existing experimental data a new level of understanding of electronic excitations has been established at the molecular level. The present study extends and confirms conclusions reached for other cobalamins. In particular, the better performance of the BP86 functional, rather than hybrid-type, was observed in terms of the excitations associated with both Co d and corrin π localized transitions. In addition, the lowest energy band was associated with multiple metal-to-ligand charge transfer excitations as opposed to the commonly assumed view of a single π → π* transition followed by vibrational progression. Finally, the use of the full cob(I)alamin structure, instead of simplified molecular models, shed new light on the spectral analyses of cobalamin systems and revealed new challenges of this approach related to long-range charge transfer excitations involving side chains.
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Affiliation(s)
- Karina Kornobis
- Department of Chemistry, University of Louisville, 2320 South Brook Street, Louisville, Kentucky 40292, United States
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Meister W, Hennig SE, Jeoung JH, Lendzian F, Dobbek H, Hildebrandt P. Complex Formation with the Activator RACo Affects the Corrinoid Structure of CoFeSP. Biochemistry 2012; 51:7040-2. [DOI: 10.1021/bi300795n] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Wiebke Meister
- Technische Universität Berlin, Institut für Chemie, Sekr. PC14, Straße
des 17. Juni 135, D-10623 Berlin, Germany
| | - Sandra E. Hennig
- Humboldt-Universität zu Berlin, Institut für Biologie, Strukturbiologie/Biochemie,
Philippstraße 13, D-10115 Berlin, Germany
| | - Jae-Hun Jeoung
- Humboldt-Universität zu Berlin, Institut für Biologie, Strukturbiologie/Biochemie,
Philippstraße 13, D-10115 Berlin, Germany
| | - Friedhelm Lendzian
- Technische Universität Berlin, Institut für Chemie, Sekr. PC14, Straße
des 17. Juni 135, D-10623 Berlin, Germany
| | - Holger Dobbek
- Humboldt-Universität zu Berlin, Institut für Biologie, Strukturbiologie/Biochemie,
Philippstraße 13, D-10115 Berlin, Germany
| | - Peter Hildebrandt
- Technische Universität Berlin, Institut für Chemie, Sekr. PC14, Straße
des 17. Juni 135, D-10623 Berlin, Germany
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Co+–H interaction inspired alternate coordination geometries of biologically important cob(I)alamin: possible structural and mechanistic consequences for methyltransferases. J Biol Inorg Chem 2012; 17:1107-21. [DOI: 10.1007/s00775-012-0924-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Accepted: 07/03/2012] [Indexed: 10/28/2022]
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Abstract
The density functional calculations suggest that the expansion of the corrin macrocycle's N(4) core by 0.06-0.10 Å leads to an appreciable lowering of 100-150 mV vs. saturated calomel electrode in the reduction potentials of two biologically important B(12) cofactors namely methylcobalamin and adenosylcobalamin respectively. This redox tuning of B(12) cofactors may encourage the electron transfer-based activation mechanism for B(12)-dependent enzymes.
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Affiliation(s)
- Manoj Kumar
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, USA
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