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Nesbit MA, Oyala PH, Peters JC. Characterization of the Earliest Intermediate of Fe-N 2 Protonation: CW and Pulse EPR Detection of an Fe-NNH Species and Its Evolution to Fe-NNH 2.. J Am Chem Soc 2019; 141:8116-8127. [PMID: 31046258 DOI: 10.1021/jacs.8b12082] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Iron diazenido species (Fe(NNH)) have been proposed as the earliest intermediates of catalytic N2-to-NH3 conversion (N2RR) mediated by synthetic iron complexes and relatedly as intermediates of N2RR by nitrogenase enzymes. However, direct identification of such iron species, either during or independent of catalysis, has proven challenging owing to their high degree of instability. The isolation of more stable silylated diazenido analogues, Fe(NNSiR3), and also of further downstream intermediates (e.g., Fe(NNH2)), nonetheless points to Fe(NNH) as the key first intermediate of protonation in synthetic systems. Herein we show that low-temperature protonation of a terminally bound Fe-N2- species, supported by a bulky trisphosphinoborane ligand (ArP3B), generates an S = 1/2 terminal Fe(NNH) species that can be detected and characterized by continuous-wave (CW) and pulse EPR techniques. The 1H-hyperfine for ArP3BFe(NNH) derived from the presented ENDOR studies is diagnostic for the distally bound H atom ( aiso = 16.5 MHz). The Fe(NNH) species evolves further to cationic [Fe(NNH2)]+ in the presence of additional acid, the latter being related to a previously characterized [Fe(NNH2)]+ intermediate of N2RR mediated by a far less encumbered iron tris(phosphine)borane catalyst. While catalysis is suppressed in the present sterically very crowded system, N2-to-NH3 conversion can nevertheless be demonstrated. These observations in sum add support to the idea that Fe(NNH) plays a central role as the earliest intermediate of Fe-mediated N2RR in a synthetic system.
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Affiliation(s)
- Mark A Nesbit
- Division of Chemistry and Chemical Engineering , California Institute of Technology , Pasadena , California 91125 , United States
| | - Paul H Oyala
- Division of Chemistry and Chemical Engineering , California Institute of Technology , Pasadena , California 91125 , United States
| | - Jonas C Peters
- Division of Chemistry and Chemical Engineering , California Institute of Technology , Pasadena , California 91125 , United States
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Adam SM, Wijeratne GB, Rogler PJ, Diaz DE, Quist DA, Liu JJ, Karlin KD. Synthetic Fe/Cu Complexes: Toward Understanding Heme-Copper Oxidase Structure and Function. Chem Rev 2018; 118:10840-11022. [PMID: 30372042 PMCID: PMC6360144 DOI: 10.1021/acs.chemrev.8b00074] [Citation(s) in RCA: 145] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Heme-copper oxidases (HCOs) are terminal enzymes on the mitochondrial or bacterial respiratory electron transport chain, which utilize a unique heterobinuclear active site to catalyze the 4H+/4e- reduction of dioxygen to water. This process involves a proton-coupled electron transfer (PCET) from a tyrosine (phenolic) residue and additional redox events coupled to transmembrane proton pumping and ATP synthesis. Given that HCOs are large, complex, membrane-bound enzymes, bioinspired synthetic model chemistry is a promising approach to better understand heme-Cu-mediated dioxygen reduction, including the details of proton and electron movements. This review encompasses important aspects of heme-O2 and copper-O2 (bio)chemistries as they relate to the design and interpretation of small molecule model systems and provides perspectives from fundamental coordination chemistry, which can be applied to the understanding of HCO activity. We focus on recent advancements from studies of heme-Cu models, evaluating experimental and computational results, which highlight important fundamental structure-function relationships. Finally, we provide an outlook for future potential contributions from synthetic inorganic chemistry and discuss their implications with relevance to biological O2-reduction.
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Affiliation(s)
- Suzanne M. Adam
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Gayan B. Wijeratne
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Patrick J. Rogler
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Daniel E. Diaz
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - David A. Quist
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Jeffrey J. Liu
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Kenneth D. Karlin
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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Huang X, Groves JT. Oxygen Activation and Radical Transformations in Heme Proteins and Metalloporphyrins. Chem Rev 2018; 118:2491-2553. [PMID: 29286645 PMCID: PMC5855008 DOI: 10.1021/acs.chemrev.7b00373] [Citation(s) in RCA: 591] [Impact Index Per Article: 98.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Indexed: 12/20/2022]
Abstract
As a result of the adaptation of life to an aerobic environment, nature has evolved a panoply of metalloproteins for oxidative metabolism and protection against reactive oxygen species. Despite the diverse structures and functions of these proteins, they share common mechanistic grounds. An open-shell transition metal like iron or copper is employed to interact with O2 and its derived intermediates such as hydrogen peroxide to afford a variety of metal-oxygen intermediates. These reactive intermediates, including metal-superoxo, -(hydro)peroxo, and high-valent metal-oxo species, are the basis for the various biological functions of O2-utilizing metalloproteins. Collectively, these processes are called oxygen activation. Much of our understanding of the reactivity of these reactive intermediates has come from the study of heme-containing proteins and related metalloporphyrin compounds. These studies not only have deepened our understanding of various functions of heme proteins, such as O2 storage and transport, degradation of reactive oxygen species, redox signaling, and biological oxygenation, etc., but also have driven the development of bioinorganic chemistry and biomimetic catalysis. In this review, we survey the range of O2 activation processes mediated by heme proteins and model compounds with a focus on recent progress in the characterization and reactivity of important iron-oxygen intermediates. Representative reactions initiated by these reactive intermediates as well as some context from prior decades will also be presented. We will discuss the fundamental mechanistic features of these transformations and delineate the underlying structural and electronic factors that contribute to the spectrum of reactivities that has been observed in nature as well as those that have been invented using these paradigms. Given the recent developments in biocatalysis for non-natural chemistries and the renaissance of radical chemistry in organic synthesis, we envision that new enzymatic and synthetic transformations will emerge based on the radical processes mediated by metalloproteins and their synthetic analogs.
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Affiliation(s)
- Xiongyi Huang
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
- Department
of Chemistry, California Institute of Technology, Pasadena, California 91125, United States
| | - John T. Groves
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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Oszajca M, Franke A, Brindell M, Stochel G, van Eldik R. Redox cycling in the activation of peroxides by iron porphyrin and manganese complexes. ‘Catching’ catalytic active intermediates. Coord Chem Rev 2016. [DOI: 10.1016/j.ccr.2015.01.013] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Abstract
In order to address how diverse metalloprotein active sites, in particular those containing iron and copper, guide O₂binding and activation processes to perform diverse functions, studies of synthetic models of the active sites have been performed. These studies have led to deep, fundamental chemical insights into how O₂coordinates to mono- and multinuclear Fe and Cu centers and is reduced to superoxo, peroxo, hydroperoxo, and, after O-O bond scission, oxo species relevant to proposed intermediates in catalysis. Recent advances in understanding the various factors that influence the course of O₂activation by Fe and Cu complexes are surveyed, with an emphasis on evaluating the structure, bonding, and reactivity of intermediates involved. The discussion is guided by an overarching mechanistic paradigm, with differences in detail due to the involvement of disparate metal ions, nuclearities, geometries, and supporting ligands providing a rich tapestry of reaction pathways by which O₂is activated at Fe and Cu sites.
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Franke A, Fertinger C, van Eldik R. Axial Ligand and Spin-State Influence on the Formation and Reactivity of Hydroperoxo-Iron(III) Porphyrin Complexes. Chemistry 2012; 18:6935-49. [DOI: 10.1002/chem.201103036] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 12/29/2011] [Indexed: 11/12/2022]
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Egawa T, Yoshioka S, Takahashi S, Hori H, Nagano S, Shimada H, Ishimori K, Morishima I, Suematsu M, Ishimura Y. Kinetic and spectroscopic characterization of a hydroperoxy compound in the reaction of native myoglobin with hydrogen peroxide. J Biol Chem 2003; 278:41597-606. [PMID: 12902339 DOI: 10.1074/jbc.m210383200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The reaction of metmyoglobin with H2O2 was investigated in a pH range between 8.5 and 6.0 with the aid of stopped flow-rapid scan and rapid freezing-EPR techniques. Singular value decomposition analyses of the stopped flow data at pH 8.5 revealed that a spectral species previously unknown accumulated during the reaction and exhibited a Soret absorption maximum at >/=423 nm. In the EPR experiments, the new species exhibited a set of g values at 2.32, 2.19, and 1.94, indicating that the species was assignable to a ferric hydroperoxy (Fe(III)[O-O-H]-) compound. In contrast, the hydroperoxy compound scarcely accumulated in the reaction at pH 6.0, and the dominant intermediate species accumulated was compound I, which was derived from the oxygen-oxygen bond cleavage of the hydroperoxy compound. The accumulated amount of the hydroperoxy compound relative to compound I showed a pH dependence with an apparent pKa (pKaapp) from 6.95 to 7.27 depending on the metmyoglobins examined. This variation in pKaapp paralleled that in pKa of the acid-alkaline transition (pKaAB) of metmyoglobins, suggesting that the accumulation of hydroperoxy compound is controlled by the distal histidine. We propose that the H2O2 activation by metmyoglobin is promoted at the acidic condition due to the imidazolium form of the distal histidine, and we further propose that the controlled protonation state of the distal histidine is important for the facile O-O bond cleavage in heme peroxidases.
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Affiliation(s)
- Tsuyoshi Egawa
- Department of Biochemistry, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan.
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Denisov IG, Ikeda-Saito M, Yoshida T, Sligar SG. Cryogenic absorption spectra of hydroperoxo-ferric heme oxygenase, the active intermediate of enzymatic heme oxygenation. FEBS Lett 2002; 532:203-6. [PMID: 12459490 DOI: 10.1016/s0014-5793(02)03674-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Using radiolysis with (32)P enriched phosphate as an internal source of ionizing radiation, the formation of hydroperoxo-ferric complex from oxy-ferrous precursor with a high yield was monitored at 77 K in heme oxygenase (HO) by means of optical absorption spectroscopy. Well-resolved absorption spectra (maxima at 421 nm, 530 nm, 557 nm) of hydroperoxo-ferric intermediate of this heme enzyme were measured in 70% glycerol/buffer frozen glasses. After annealing at 210-215 K this complex converts to the product complex, alpha-meso hydroxyheme-HO. No heme degradation products were formed in control experiments with ferric HO or other heme proteins.
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Affiliation(s)
- Ilia G Denisov
- Department of Biochemistry, University of Illinois, 116 Morrill Hall, 505 S. Goodwin Avenue, Urbana-Champaign, IL 61801, USA
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Denisov IG, Makris TM, Sligar SG. Formation and decay of hydroperoxo-ferric heme complex in horseradish peroxidase studied by cryoradiolysis. J Biol Chem 2002; 277:42706-10. [PMID: 12215454 DOI: 10.1074/jbc.m207949200] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Using radiolytic reduction of the oxy-ferrous horseradish peroxidase (HRP) at 77 K, we observed the formation and decay of the putative intermediate, the hydroperoxo-ferric heme complex, often called "Compound 0." This intermediate is common for several different enzyme systems as the precursor of the Compound I (ferryl-oxo pi-cation radical) intermediate. EPR and UV-visible absorption spectra show that protonation of the primary intermediate of radiolytic reduction, the peroxo-ferric complex, to form the hydroperoxo-ferric complex is completed only after annealing at temperatures 150-180 K. After further annealing at 195-205 K, this complex directly transforms to ferric HRP without any observable intervening species. The lack of Compound I formation is explained by inability of the enzyme to deliver the second proton to the distal oxygen atom of hydroperoxide ligand, shown to be necessary for dioxygen bond heterolysis on the "oxidase pathway," which is non-physiological for HRP. Alternatively, the physiological substrate H2O2 brings both protons to the active site of HRP, and Compound I is subsequently formed via rearrangement of the proton from the proximal to the distal oxygen atom of the bound peroxide.
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Affiliation(s)
- Ilia G Denisov
- Department of Biochemistry, Center for Biophysics and Computational Biology, University of Illinois, Urbana-Champaign, Illinois 61801, USA
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Huy NT, Kamei K, Yamamoto T, Kondo Y, Kanaori K, Takano R, Tajima K, Hara S. Clotrimazole binds to heme and enhances heme-dependent hemolysis: proposed antimalarial mechanism of clotrimazole. J Biol Chem 2002; 277:4152-8. [PMID: 11707446 DOI: 10.1074/jbc.m107285200] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Two recent studies have demonstrated that clotrimazole, a potent antifungal agent, inhibits the growth of chloroquine-resistant strains of the malaria parasite, Plasmodium falciparum, in vitro. We explored the mechanism of antimalarial activity of clotrimazole in relation to hemoglobin catabolism in the malaria parasite. Because free heme produced from hemoglobin catabolism is highly toxic to the malaria parasite, the parasite protects itself by polymerizing heme into insoluble nontoxic hemozoin or by decomposing heme coupled to reduced glutathione. We have shown that clotrimazole has a high binding affinity for heme in aqueous 40% dimethyl sulfoxide solution (association equilibrium constant: K(a) = 6.54 x 10(8) m(-2)). Even in water, clotrimazole formed a stable and soluble complex with heme and suppressed its aggregation. The results of optical absorption spectroscopy and electron spin resonance spectroscopy revealed that the heme-clotrimazole complex assumes a ferric low spin state (S = 1/2), having two nitrogenous ligands derived from the imidazole moieties of two clotrimazole molecules. Furthermore, we found that the formation of heme-clotrimazole complexes protects heme from degradation by reduced glutathione, and the complex damages the cell membrane more than free heme. The results described herein indicate that the antimalarial activity of clotrimazole might be due to a disturbance of hemoglobin catabolism in the malaria parasite.
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Affiliation(s)
- Nguyen Tien Huy
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
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Kagan VE, Kozlov AV, Tyurina YY, Shvedova AA, Yalowich JC. Antioxidant mechanisms of nitric oxide against iron-catalyzed oxidative stress in cells. Antioxid Redox Signal 2001; 3:189-202. [PMID: 11396475 DOI: 10.1089/152308601300185160] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Three distinct antioxidant pathways are considered through which iron-catalyzed oxidative stress may be regulated by nitric oxide (NO). The first two pathways involve direct redox interactions of NO with iron catalytic sites and represent a fast response that may be considered an emergency mechanism to protect cells from the consequences of acute and intensive oxidative stress. These are (i) NO-induced nitrosylation at heme and non-heme iron catalytic sites that is capable of directly reducing oxoferryl-associated radicals, (ii) formation of nitrosyl complexes with intracellular "loosely" bound redox-active iron, and (iii) an indirect regulatory pathway that may function as an adaptive mechanism that becomes operational upon long-term exposure of cells to NO. In the latter pathway, NO down-regulates expression of iron-containing proteins to prevent their catalytic prooxidant reactions.
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Affiliation(s)
- V E Kagan
- Department of Environmental and Occupational Health, University of Pittsburgh, PA 15238, USA.
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12
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Satoh W, Masumoto S, Yamamoto Y, Akiba KY. Synthesis and properties of group 15 element porphyrin peroxides. HETEROATOM CHEMISTRY 2001. [DOI: 10.1002/hc.1065] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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13
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Sobolev A, Babushkin D, Talsi E. Stability and reactivity of low-spin ferric hydroperoxo and alkylperoxo complexes with bipyridine and phenantroline ligands. ACTA ACUST UNITED AC 2000. [DOI: 10.1016/s1381-1169(00)00197-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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14
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Davydov RM, Yoshida T, Ikeda-Saito M, Hoffman BM. Hydroperoxy-Heme Oxygenase Generated by Cryoreduction Catalyzes the Formation of α-meso-Hydroxyheme as Detected by EPR and ENDOR. J Am Chem Soc 1999. [DOI: 10.1021/ja992425v] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Tajima K, Tada K, Jinno J, Edo T, Mano H, Azuma N, Makino K. Mechanisms for the formation of six-coordinate Fe(III)TPP-peroxide complexes studied by simultaneous ESR and optical measurements. Inorganica Chim Acta 1997. [DOI: 10.1016/s0020-1693(96)05131-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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16
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Sobolev AP, Babushkin DE, Talsi EP. Formation of low-spin peroxoiron(III) complexes in Gif-type catalytic systems. MENDELEEV COMMUNICATIONS 1996. [DOI: 10.1070/mc1996v006n01abeh000567] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Tajima K, Oka S, Edo T, Miyake S, Mano H, Mukai K, Sakurai H, Ishizu K. Optical absorption and EPR studies on a six-coordinate iron(III)–tetramesitylporphyrin–hydrogen peroxide complex having a nitrogenous axial ligand. ACTA ACUST UNITED AC 1995. [DOI: 10.1039/c39950001507] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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18
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Kinetics and intermediates in the autoxidation of (cyclidene)iron(II) dioxygen carriers in a variety of solvent systems. Coord Chem Rev 1993. [DOI: 10.1016/0010-8545(93)80026-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Tajima K, Mikami K, Tada K, Oka S, Ishizu K, Ohya-Nishiguchi H. Autoreduction of a six-coordinate Fe(III)TPP-peroxide complex by heterolytic ironoxygen bond cleavage. Inorganica Chim Acta 1992. [DOI: 10.1016/s0020-1693(00)85823-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Jinno J, Shigematsu M, Tajima K, Sakurai H, Ohya-Nishiguchi H, Ishizu K. Coordination structure and chemical reactivity of hemoprotein-butyl peroxide complex. Biochem Biophys Res Commun 1991; 176:675-81. [PMID: 1850999 DOI: 10.1016/s0006-291x(05)80237-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
ESR and optical spectra ascribed to be the hemoprotein-butylperoxide complex were detected for the frozen aqueous solution containing whale met-Mb and t- or n-butylhydroperoxide at pH 10. The observed ESR and optical parameters of the complex were characteristic to those of six coordinate ferric low-spin complexes, having the butylperoxide anion at the axial position of heme. pH dependent ESR measurements demonstrated the formation of the complex in the biological pH regions (7.0). Time dependent ESR and optical measurements indicated that the complex may be one of the intermediate species in the processes of heme degradation reaction induced by butylperoxide.
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Affiliation(s)
- J Jinno
- Research Institute, Ohtsuka Pharmaceutical Co., Ltd., Tokushima, Japan
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22
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Heme-Hydrogen Peroxide Complex Formation as Studied by ESR and Optical Spectroscopy. ACTA ACUST UNITED AC 1991. [DOI: 10.1016/s0167-2991(08)62846-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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23
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Structure and Reactivity of Fe(III)TPP-Oxygen-Skatole Ternary Complex in Tryptophan Dioxygenase Model Reaction System. ACTA ACUST UNITED AC 1991. [DOI: 10.1016/s0167-2991(08)62863-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Tajima K, Yoshino M, Mikami K, Edo T, Ishizu K, Ohya-Nishiguchi H. Important role of Fe(III)TPP-oxygen-skatole ternary complex in tryptophan dioxygenase model reaction system. Inorganica Chim Acta 1990. [DOI: 10.1016/s0020-1693(00)80454-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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25
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Tajima K. Formation of hemoprotein-alkylperoxide complexes demonstrated by ESR and optical absorption spectroscopy. Inorganica Chim Acta 1990. [DOI: 10.1016/s0020-1693(00)80520-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Tajima K, Shigematsu M, Jinno J, Kawano Y, Mikami K, Ishizu K, Ohya-Nishiguchi H, Shigamatsu M. A possible model of hemoprotein-fatty acid peroxide complex demonstrated by electron spin resonance. Biochem Biophys Res Commun 1990; 166:924-30. [PMID: 2154224 DOI: 10.1016/0006-291x(90)90899-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Coordination reaction between linolenic-acid-hydroperoxide (LHPO) and chloro(5, 10, 15, 20-tetraphenyl)-porphyrinato iron (III), Fe(III)TPPCl, was investigated by means of ESR. ESR spectra of the ferric low-spin complex (g1 = 2.336, g2 = 2.174 and g3 = 1.929) was recorded for the mixture prepared by mixing Fe(III)TPPCl and LHPO at -78 degrees C in the presence of alkaline reagent. ESR line width of complex was broadened when 17O2 labeled LHPO was used for ESR measurement. In terms of the g-parameters of the ferric low-spin species, this complex was concluded to be Fe(III)TPP(-OCH3)(-OO-linolenic acid) type complex.
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Affiliation(s)
- K Tajima
- Department of Chemistry, Faculty of Science, Ehime University, Matsuyama, Japan
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Tajima K, Shigematsu M, Jinno J, Ishizu K, Ohya-Nishiguchi H. Generation of FeIIIOEP-hydrogen peroxide complex (OEP = octaethylporphyrinato) by reduction of FeIIOEP–O2with ascorbic acid sodium salt. ACTA ACUST UNITED AC 1990. [DOI: 10.1039/c39900000144] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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