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Maiorova LA, Gromova OA, Torshin IY, Bukreeva TV, Pallaeva TN, Nabatov BV, Dereven'kov IA, Bobrov YA, Bykov AA, Demidov VI, Kalacheva AG, Bogacheva TE, Grishina TR, Nikolskaya ED, Yabbarov NG. Nanoparticles of nucleotide-free analogue of vitamin B 12 formed in protein nanocarriers and their neuroprotective activity in vivo. Colloids Surf B Biointerfaces 2024; 244:114165. [PMID: 39217725 DOI: 10.1016/j.colsurfb.2024.114165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2024] [Revised: 08/16/2024] [Accepted: 08/17/2024] [Indexed: 09/04/2024]
Abstract
Recently, we have described the first supermolecular nanoentities of vitamin B12 derivative, viz. monocyano form of heptabutyl cobyrinate, unique nanoparticles with strong noncovalent intermolecular interactions, emerging optical and catalytic properties. Their nearest analogue, heptamethyl cobyrinate (ACCby), exhibits bioactivity. Here, we demonstrate the first example of the formation of nanoparticles of this nucleotide-free analogue of vitamin B12 in protein nanocarriers and neuroprotective activity in vivo of the own nanoform of the drug. The preparation and characterization of nanocarriers based on bovine serum albumin (BSA) loaded with vitamin B12 (viz. cyano- and aquacobalamins) and ACCby were performed. Nucleotide-free analogue of vitamin B12 is tightly retained by the protein structure and exists in an incorporated state in the form of nanoparticles. The effect of encapsulated drugs on the character and severity of primary generalized seizures in rats induced by the pharmacotoxicant thiosemicarbazide was studied. Cyanocobalamin and ACCby exhibited a neuroprotective effect. The best influence of the encapsulation on the effectiveness of the drugs was achieved in the case of AСCby, whose bioavailability as a neuroprotector did not change upon introduction in BSA particles, i.e., 33 % of surviving animals were observed upon ACCby administration in free form and in encapsulated state. No surviving rats were observed without the administration of drugs. Thus, BSA nanocarriers loaded by nanoparticles of nucleotide-free analogues of vitamin B12, including hydrophobic ones, can be recommended for neuroprotection and targeted delivery.
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Affiliation(s)
- Larissa A Maiorova
- Institute of Macroheterocyclic Compounds, Ivanovo State University of Chemistry and Technology, Ivanovo, Russia; Federal Research Center Computer Science and Control of Russian Academy of Sciences, Moscow, Russia.
| | - Olga A Gromova
- Federal Research Center Computer Science and Control of Russian Academy of Sciences, Moscow, Russia
| | - Ivan Yu Torshin
- Federal Research Center Computer Science and Control of Russian Academy of Sciences, Moscow, Russia
| | - Tatiana V Bukreeva
- Kurchatov Complex Crystallography and Photonics, National Research Centre "Kurchatov Institute", Moscow, Russia
| | - Tatiana N Pallaeva
- Kurchatov Complex Crystallography and Photonics, National Research Centre "Kurchatov Institute", Moscow, Russia
| | - Boris V Nabatov
- Kurchatov Complex Crystallography and Photonics, National Research Centre "Kurchatov Institute", Moscow, Russia
| | - Ilia A Dereven'kov
- Institute of Macroheterocyclic Compounds, Ivanovo State University of Chemistry and Technology, Ivanovo, Russia
| | | | | | - Vadim I Demidov
- Ivanovo State Medical University, Ministry of Health of Russia, Ivanovo, Russia
| | - Alla G Kalacheva
- Ivanovo State Medical University, Ministry of Health of Russia, Ivanovo, Russia
| | - Tatiana E Bogacheva
- Ivanovo State Medical University, Ministry of Health of Russia, Ivanovo, Russia
| | - Tatiana R Grishina
- Ivanovo State Medical University, Ministry of Health of Russia, Ivanovo, Russia
| | - Elena D Nikolskaya
- N.M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, 4 Kosygina Street, Moscow, Russia
| | - Nikita G Yabbarov
- N.M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, 4 Kosygina Street, Moscow, Russia
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2
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Elmendorf LD, Brunold TC. Vibronic Coupling in Vitamin B 12: A Combined Spectroscopic and Computational Study. Inorg Chem 2023; 62:12762-12772. [PMID: 37463115 DOI: 10.1021/acs.inorgchem.3c01305] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2023]
Abstract
Understanding the diverse reactivities of vitamin B12 and its derivatives, collectively called cobalamins, requires detailed knowledge of their geometric and electronic structures. Electronic absorption (Abs) and resonance Raman (rR) spectroscopies have proven invaluable in this area, particularly when used in concert with computational techniques such as density functional theory (DFT). There remain, however, lingering uncertainties in the computational description of electronic excited states of cobalamins, particularly surrounding the vibronic coupling that impacts the Abs bandshapes and gives rise to rR enhancement of vibrational modes. Past computational analyses of the vibrational spectra of cobalamins have either neglected rR enhancement or calculated rR enhancement for only a small number of modes. In the present study, we used the recently developed ORCA_ASA computational tool in conjunction with the popular B3LYP and BP86 functionals to predict Abs bandshapes and rR spectra for vitamin B12. The ORCA_ASA/B3LYP-computed Abs envelope in the visible spectral region and rR spectra of vitamin B12 agree remarkably well with our experimental data, while BP86 fails to reproduce both. This finding represents a significant advance in our understanding of how these two commonly used density functionals differently model the electronic properties of cobalamins. Guided by the computed frequencies for the Co-C stretching and Co-C-N bending modes, we identified, for the first time, isotope-sensitive features in our rR spectra of 12CNCbl and 13CNCbl that can be assigned to these modes. A normal coordinate analysis of the experimentally determined Co-C stretching and Co-C-N bending frequencies indicates that the Co-C force constant for vitamin B12 is 2.67 mdyn/Å, considerably larger than the Co-C force constants reported for alkylcobalamins.
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Affiliation(s)
- Laura D Elmendorf
- Department of Chemistry, University of Wisconsin - Madison, Madison, Wisconsin 53706, United States
| | - Thomas C Brunold
- Department of Chemistry, University of Wisconsin - Madison, Madison, Wisconsin 53706, United States
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3
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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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4
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Toda MJ, Lodowski P, Mamun AA, Jaworska M, Kozlowski PM. Photolytic properties of the biologically active forms of vitamin B12. Coord Chem Rev 2019. [DOI: 10.1016/j.ccr.2018.12.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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5
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Dereven’kov IA, Makarov SV. Mechanistic studies on the reaction between glutathionylcobalamin and selenocysteine. J COORD CHEM 2019. [DOI: 10.1080/00958972.2019.1570166] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Ilia A. Dereven’kov
- Institute of Macroheterocyclic Compounds, Ivanovo State University of Chemistry and Technology, Ivanovo, Russian Federation
| | - Sergei V. Makarov
- Institute of Macroheterocyclic Compounds, Ivanovo State University of Chemistry and Technology, Ivanovo, Russian Federation
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6
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Dereven’kov IA, Tsaba LV, Pokrovskaya EA, Makarov SV. Studies on the interaction of aquacobalamin with cysteinesulfinic and cysteic acids, hypotaurine and taurine. J COORD CHEM 2018. [DOI: 10.1080/00958972.2018.1515927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Ilia A. Dereven’kov
- Department of Food Chemistry, Ivanovo State University of Chemistry and Technology, Ivanovo, Russian Federation
| | - Lubov V. Tsaba
- Department of Food Chemistry, Ivanovo State University of Chemistry and Technology, Ivanovo, Russian Federation
| | - Elizaveta A. Pokrovskaya
- Department of Food Chemistry, Ivanovo State University of Chemistry and Technology, Ivanovo, Russian Federation
| | - Sergei V. Makarov
- Department of Food Chemistry, Ivanovo State University of Chemistry and Technology, Ivanovo, Russian Federation
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7
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Sonnay M, Zelder F. Stabilizing intramolecular cobalt–imidazole coordination with a remote methyl group in the backbone of a cofactor B12–protein model. Dalton Trans 2018; 47:10443-10446. [DOI: 10.1039/c8dt01298a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This communication describes the stabilizing effect of a remote methyl group in the backbone of a cobalamin–protein mimic on intramolecular imidazole–cobalt coordination.
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Affiliation(s)
- Marjorie Sonnay
- Department of Chemistry
- University of Zurich
- CH-8057 Zurich
- Switzerland
| | - Felix Zelder
- Department of Chemistry
- University of Zurich
- CH-8057 Zurich
- Switzerland
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8
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Tumakov SO, Dereven’kov IA, Salnikov DS, Makarov SV. Kinetics and mechanism of the reaction between aquacobalamin and isoniazid. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A 2017. [DOI: 10.1134/s0036024417100405] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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9
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Cortés-Arriagada D, Toro-Labbe A, Mora JR, Rincón L, Mereau R, Torres FJ. Theoretical analysis of C-F bond cleavage mediated by cob[I]alamin-based structures. J Mol Model 2017; 23:264. [PMID: 28819880 DOI: 10.1007/s00894-017-3431-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 07/25/2017] [Indexed: 10/19/2022]
Abstract
In the present work, C-F bond cleavage mediated by the super-reduced form of cobalamin (i.e., CoICbl) was theoretically studied at the ONIOM(BP86/6-311++G(d,p):PM6) + SMD level of theory. Dispersion effects were introduced by employing Grimme's empirical dispersion at the ONIOM(BP86-D/6-311++G(d,p):PM6) + SMD level. In the first stage of the study, cobalamin was characterized in terms of the coordination number of the central cobalt atom. The ONIOM(BP86/6-311++G(d,p):PM6) results showed that the base-off form of the system is slightly more stable than its base-on counterpart (ΔE = E base-off - E base-on ~ -2 kcal/mol). The inclusion of dispersive forces in the description of the system stabilizes the base-on form, which becomes as stable as its base-off counterpart. Moreover, in the latter case, the energy barrier separating both structures was found to be negligible, with a computed value of 1.02 kcal/mol. In the second stage of the work, the reaction CoICbl + CH3F → MeCbl + F- was studied considering the base-off and the base-on forms of CoICbl. The reaction that occurs in the presence of the base-on form of CoICbl was found to be kinetically more favorable (ΔE ≠ = 13.7 kcal/mol) than that occurring in the presence of the base-off form (ΔE ≠ = 41.2 kcal/mol). Further reaction-force analyses of the processes showed that the energy barrier to C-F bond cleavage arises largely due to structural rearrangements when the reaction occurs on the base-on form of the CoICbl complex, but is mainly due to electronic rearrangements when the reaction takes place on the base-off form of the complex. The latter behavior emerges from differences in the synchronicity of the bond strengthening/weakening processes along the reaction path; the base-on mode of CoICbl is able to decrease the synchronicity of the chemical events. This work gives new molecular-level insights into the role of Cbl-based systems in the cleavage of C-F bonds. These insights have potential implications for research into processes for degrading fluorine-containing pollutants.
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Affiliation(s)
- D Cortés-Arriagada
- Programa Institucional de Fomento a la Investigación, Desarrollo e Innovación, Universidad Tecnológica Metropolitana, Ignacio Valdivieso 2409, P.O. Box 8940577, San Joaquín, Santiago, Chile
| | - A Toro-Labbe
- Nucleus Millennium Chemical Processes and Catalysis (CPC), Laboratorio de Química Teórica Computacional (QTC), Facultad de Química, Pontificia Universidad Católica de Chile, Casilla 306, Correo 22, Santiago, Chile
| | - J R Mora
- Instituto de Simulación Computacional (ISC-USFQ), Diego de Robles y Vía Interoceánica, Universidad San Francisco de Quito, 17-1200-841, Quito, Ecuador.,Grupo de Química Computacional y Teórica (QCT-USFQ), Departamento de Ingeniería Química, Diego de Robles y Vía Interoceánica, Universidad San Francisco de Quito, 17-1200-841, Quito, Ecuador
| | - L Rincón
- Instituto de Simulación Computacional (ISC-USFQ), Diego de Robles y Vía Interoceánica, Universidad San Francisco de Quito, 17-1200-841, Quito, Ecuador.,Grupo de Química Computacional y Teórica (QCT-USFQ), Departamento de Ingeniería Química, Diego de Robles y Vía Interoceánica, Universidad San Francisco de Quito, 17-1200-841, Quito, Ecuador
| | - R Mereau
- Université de Bordeaux, ISM, UMR 5255, 351 Cours de la Libération, F-33405, Talence, France
| | - F J Torres
- Instituto de Simulación Computacional (ISC-USFQ), Diego de Robles y Vía Interoceánica, Universidad San Francisco de Quito, 17-1200-841, Quito, Ecuador. .,Grupo de Química Computacional y Teórica (QCT-USFQ), Departamento de Ingeniería Química, Diego de Robles y Vía Interoceánica, Universidad San Francisco de Quito, 17-1200-841, Quito, Ecuador.
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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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11
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Sajan A, Birke RL. The Reductive Cleavage Mechanism and Complex Stability of Glutathionyl-Cobalamin in Acidic Media. ELECTROANAL 2016. [DOI: 10.1002/elan.201600341] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Abin Sajan
- Department of Chemistry and Biochemistry; The City College of the City University of New York; NY 10031 USA
| | - Ronald L. Birke
- Department of Chemistry and Biochemistry; The City College of the City University of New York; NY 10031 USA
- Ph. D. Program in Chemistry; The Graduate Center of the City University of New York; 10016 USA
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12
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Pallares IG, Moore TC, Escalante-Semerena JC, Brunold TC. Spectroscopic Studies of the EutT Adenosyltransferase from Salmonella enterica: Mechanism of Four-Coordinate Co(II)Cbl Formation. J Am Chem Soc 2016; 138:3694-704. [PMID: 26886077 DOI: 10.1021/jacs.5b11708] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
EutT from Salmonella enterica is a member of a class of enzymes termed ATP:Co(I)rrinoid adenosyltransferases (ACATs), implicated in the biosynthesis of adenosylcobalamin (AdoCbl). In the presence of cosubstrate ATP, ACATs raise the Co(II)/Co(I) reduction potential of their cob(II)alamin [Co(II)Cbl] substrate by >250 mV via the formation of a unique four-coordinate (4c) Co(II)Cbl species, thereby facilitating the formation of a "supernucleophilic" cob(I)alamin intermediate required for the formation of the AdoCbl product. Previous kinetic studies of EutT revealed the importance of a HX11CCX2C(83) motif for catalytic activity and have led to the proposal that residues in this motif serve as the binding site for a divalent transition metal cofactor [e.g., Fe(II) or Zn(II)]. This motif is absent in other ACAT families, suggesting that EutT employs a distinct mechanism for AdoCbl formation. To assess how metal ion binding to the HX11CCX2C(83) motif affects the relative yield of 4c Co(II)Cbl generated in the EutT active site, we have characterized several enzyme variants by using electronic absorption, magnetic circular dichroism, and electron paramagnetic resonance spectroscopies. Our results indicate that Fe(II) or Zn(II) binding to the HX11CCX2C(83) motif of EutT is required for promoting the formation of 4c Co(II)Cbl. Intriguingly, our spectroscopic data also reveal the presence of an equilibrium between five-coordinate "base-on" and "base-off" Co(II)Cbl species bound to the EutT active site at low ATP concentrations, which shifts in favor of "base-off" Co(II)Cbl in the presence of excess ATP, suggesting that the base-off species serves as a precursor to 4c Co(II)Cbl.
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Affiliation(s)
- Ivan G Pallares
- Department of Chemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
| | - Theodore C Moore
- Department of Microbiology, University of Georgia , Athens, Georgia 30602, United States
| | | | - Thomas C Brunold
- Department of Chemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
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13
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Dereven’kov IA, Thi TTB, Salnikov DS, Makarov SV. Effect of amino acids on the interaction between cobalamin(II) and dehydroascorbic acid. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A 2016. [DOI: 10.1134/s0036024416030080] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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14
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Rodgers ZL, Shell TA, Brugh AM, Nowotarski HL, Forbes MDE, Lawrence DS. Fluorophore Assisted Photolysis of Thiolato-Cob(III)alamins. Inorg Chem 2016; 55:1962-9. [PMID: 26848595 DOI: 10.1021/acs.inorgchem.5b02036] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Cobalamins are known to react with thiols to yield stable β-axial Co(III)-S bonded thiolato-cobalamin complexes. However, in stark contrast to the Co-C bond in alkylcobalamins, the photolability of the Co-S bond in thiolato-cobalamins remains undetermined. We have investigated the photolysis of N-acetylcysteinyl cob(III)alamin at several wavelengths within the ultraviolet and visible spectrum. To aid in photolysis, we show that attaching fluorophore "antennae" to the cobalamin scaffold can improve photolytic efficiency by up to an order of magnitude. Additionally, electron paramagnetic resonance confirms previous conjectures that the photolysis of thiolato-cobalamins at wavelengths as long as 546 nm produces thiyl radicals.
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Affiliation(s)
- Zachary L Rodgers
- Department of Chemistry, ‡Division of Chemical Biology and Medicinal Chemistry, and §Department of Pharmacology, University of North Carolina , Chapel Hill, North Carolina 27599, United States
| | - Thomas A Shell
- Department of Chemistry, ‡Division of Chemical Biology and Medicinal Chemistry, and §Department of Pharmacology, University of North Carolina , Chapel Hill, North Carolina 27599, United States
| | - Alexander M Brugh
- Department of Chemistry, ‡Division of Chemical Biology and Medicinal Chemistry, and §Department of Pharmacology, University of North Carolina , Chapel Hill, North Carolina 27599, United States
| | - Hannah L Nowotarski
- Department of Chemistry, ‡Division of Chemical Biology and Medicinal Chemistry, and §Department of Pharmacology, University of North Carolina , Chapel Hill, North Carolina 27599, United States
| | - Malcolm D E Forbes
- Department of Chemistry, ‡Division of Chemical Biology and Medicinal Chemistry, and §Department of Pharmacology, University of North Carolina , Chapel Hill, North Carolina 27599, United States
| | - David S Lawrence
- Department of Chemistry, ‡Division of Chemical Biology and Medicinal Chemistry, and §Department of Pharmacology, University of North Carolina , Chapel Hill, North Carolina 27599, United States
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16
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Deb T, Jensen MP. Electrophilic alkylation of pseudotetrahedral nickel(II) arylthiolate complexes. Inorg Chem 2015; 54:87-96. [PMID: 25494529 DOI: 10.1021/ic5018328] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A kinetic study is reported for reactions of pseudotetrahedral nickel(II) arylthiolate complexes [(Tp(R,Me))Ni-SAr] (Tp(R,Me) = hydrotris{3-R-5-methyl-1-pyrazolyl}borate, R = Me, Ph, and Ar = C6H5, C6H4-4-Cl, C6H4-4-Me, C6H4-4-OMe, 2,4,6-Me3C6H2, 2,4,6-(i)Pr3C6H2) with organic electrophiles R'X (i.e., MeI, EtI, BzBr) in low-polarity organic solvents (toluene, THF, chloroform, dichloromethane, or 1,2-dichloroethane), yielding a pseudotetrahedral halide complex [(Tp(R,Me))Ni-X] (X = Cl, Br, I) and the corresponding organosulfide R'SAr. Competitive reactions with halogenated solvents and adventitious air were also examined. Akin to reactions of analogous and biomimetic zinc complexes, a pertinent mechanistic question is the nature of the reactive nucleophile, either an intact thiolate complex or a free arylthiolate resulting from a dissociative pre-equilibrium. The observed kinetics conformed to a second-order rate law, first order with respect to the complex and electrophile, and no intermediate complexes were observed. In the absence of a mechanistically diagnostic rate law, a variety of mechanistic probes were examined, including kinetic effects of varying the metal, solvent, electrophile, and temperature, as well as the 3-pyrazolyl and arylthiolate substituents. Compared to zinc analogues, the effect of Ni-SAr covalency is also of interest herein. The results are broadly interpreted with respect to the disparate mechanistic pathways.
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Affiliation(s)
- Tapash Deb
- Department of Chemistry and Biochemistry, Ohio University , Athens, Ohio 45701, United States
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17
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Abstract
Nitrosylcobalamin (NOCbl) is readily formed when Co(II)balamin reacts with nitric oxide (NO) gas. NOCbl has been implicated in the inhibition of various B12-dependent enzymes, as well as in the modulation of blood pressure and of the immunological response. Previous studies revealed that among the known biologically relevant cobalamin species, NOCbl possesses the longest bond between the Co ion and the axially bound 5,6-dimethylbenzimidazole base, which was postulated to result from a strong trans influence exerted by the NO ligand. In this study, various spectroscopic (electronic absorption, circular dichroism, magnetic circular dichroism, and resonance Raman) and computational (density functional theory (DFT) and time-dependent DFT) techniques were used to generate experimentally validated electronic structure descriptions for the "base-on" and "base-off" forms of NOCbl. Further insights into the principal Co-ligand bonding interactions were obtained by carrying out natural bond orbital analyses. Collectively, our results indicate that the formally unoccupied Co 3dz(2) orbital engages in a highly covalent bonding interaction with the filled NO π* orbital and that the Co-NO bond is strengthened further by sizable π-backbonding interactions that are not present in any other Co(III)Cbl characterized to date. Because of the substantial NO(-) to Co(III) charge donation, NOCbl is best described as a hybrid of Co(III)-NO(-) and Co(II)-NO(•) resonance structures. In contrast, our analogous computational characterization of a related species, superoxocobalamin, reveals that in this case a Co(III)-O2(-) description is adequate due to the larger oxidizing power of O2 versus NO. The implications of our results with respect to the unusual structural features and thermochromism of NOCbl and the proposed inhibition mechanisms of B12-dependent enzymes by NOCbl are discussed.
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Affiliation(s)
- Ivan G. Pallares
- Department of Chemistry, University of
Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Thomas C. Brunold
- Department of Chemistry, University of
Wisconsin-Madison, Madison, Wisconsin 53706, United States
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Zhou J, Riccardi D, Beste A, Smith JC, Parks JM. Mercury methylation by HgcA: theory supports carbanion transfer to Hg(II). Inorg Chem 2013; 53:772-7. [PMID: 24377658 DOI: 10.1021/ic401992y] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Many proteins use corrinoid cofactors to facilitate methyl transfer reactions. Recently, a corrinoid protein, HgcA, has been shown to be required for the production of the neurotoxin methylmercury by anaerobic bacteria. A strictly conserved Cys residue in HgcA was predicted to be a lower-axial ligand to Co(III), which has never been observed in a corrinoid protein. Here, we use density functional theory to study homolytic and heterolytic Co-C bond dissociation and methyl transfer to Hg(II) substrates with model methylcobalamin complexes containing a lower-axial Cys or His ligand to cobalt, the latter of which is commonly found in other corrinoid proteins. We find that Cys thiolate coordination to Co facilitates both methyl radical and methyl carbanion transfer to Hg(II) substrates, but carbanion transfer is more favorable overall in the condensed phase. Thus, our findings are consistent with HgcA representing a new class of corrinoid protein capable of transferring methyl groups to electrophilic substrates.
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Affiliation(s)
- Jing Zhou
- Graduate School of Genome Science and Technology, University of Tennessee , Knoxville, Tennessee 37996, United States
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19
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Rutkowska-Zbik D, Mazur G, Drzewiecka-Matuszek A, Orzeł Ł, Stochel G. Exploring novel modified vitamin B12 as a drug carrier: forecast from density functional theory modeling. J Phys Chem B 2013; 117:9655-61. [PMID: 23889131 DOI: 10.1021/jp405821k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Three non-native derivatives of vitamin B12 with imidazole, ethylenediamine, and pyrazine as cobalt(III) β-ligands were characterized by applying the BP/def2-TZVP density functional method. The binding of all three ligands is thermodynamically favorable. It is proposed that their synthesis might be possible from aquacobalamin as a starting form of vitamin B12, as has been done in the case of an imidazole derivative of B12 (Hannibal et al. Inorg. Chem. 2007, 46, 3613-3618). Furthermore, the possibility of the formation of their conjugates with cisplatin is investigated. The proposed β-ligands may serve as bridging ligands, binding to the platin ion as N-donors. In parallel, the calculations are done for the previously synthetized B12-cisplatin adduct with CN(-) as a bridging ligand and are compared with available experimental data, allowing assessment of the applied computational protocol. A good agreement between the computed and experimental structural parameters is obtained. In each of the studied structures, the Co-β-ligand bond is weaker than the Pt-β-ligand bond.
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Affiliation(s)
- Dorota Rutkowska-Zbik
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Kraków, Poland.
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20
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Parks JM, Johs A, Podar M, Bridou R, Hurt RA, Smith SD, Tomanicek SJ, Qian Y, Brown SD, Brandt CC, Palumbo AV, Smith JC, Wall JD, Elias DA, Liang L. The Genetic Basis for Bacterial Mercury Methylation. Science 2013; 339:1332-5. [DOI: 10.1126/science.1230667] [Citation(s) in RCA: 600] [Impact Index Per Article: 54.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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21
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Tahara K, Matsuzaki A, Masuko T, Kikuchi JI, Hisaeda Y. Synthesis, characterization, Co–S bond reactivity of a vitamin B12 model complex having pentafluorophenylthiolate as an axial ligand. Dalton Trans 2013; 42:6410-6. [DOI: 10.1039/c3dt00042g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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22
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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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23
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Prakash J, Kodanko JJ. Synthesis, Characterization, and Glutathionylation of Cobalamin Model Complexes [Co(N4PyCO2Me)Cl]Cl2 and [Co(Bn-CDPy3)Cl]Cl2. Inorg Chem 2012; 51:2689-98. [DOI: 10.1021/ic2026736] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Jai Prakash
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit,
Michigan 48202, United States
| | - Jeremy J. Kodanko
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit,
Michigan 48202, United States
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