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Willem H. Koppenol - One of the best experts on this subject based on the ideXlab platform.
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On the Chemical and Electrochemical One-Electron Reduction of Peroxynitrous Acid
The journal of physical chemistry. A, 2005Co-Authors: Christophe Kurz, Reinhard Kissner, Xiuqiong Zeng, Stefan Hannemann, Willem H. KoppenolAbstract:Peroxynitrous Acid was reduced by cathodic linear sweep voltammetry at a gold electrode and by iodide at pH 3.2 and 5.6. The cathodic reduction wave was identified by measuring its decay in time, which was the same as observed by optical spectroscopy. The iodide oxidation was followed by optical measurement of the triiodide formation. Both reductions show one-electron stoichiometry, with the product nαα = 0.23 ± 0.04 from the electrochemical experiments, in which α is the transfer coefficient and nα the number of electrons transferred, and an diiodine yield of ca. 0.5 equiv per equivalent of Peroxynitrous Acid. The voltammetric reduction was irreversible up to scan rates of 80 V s-1. Both reductions were pH independent in the range studied. The voltammetric reduction is most likely an irreversible elemental reaction followed by a chemical decay that cannot be observed directly. Because of the pH independence, we conclude that both reductions have a common short-lived intermediate, namely [HOONO]•-. We est...
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Peroxynitrous Acid--where is the hydroxyl radical?
IUBMB Life, 2004Co-Authors: Reinhard Kissner, Thomas Nauser, Christophe Kurz, Willem H. KoppenolAbstract:Peroxynitrite is an inorganic toxin of physiological interest, formed from the diffusion-controlled reaction of superoxide and nitrogen monoxide with a rate constant of (1.6 ± 0.3) × 1010 M - 1 s - 1. On the basis of three experiments we conclude that homolysis of the O-O bond in Peroxynitrous Acid is unlikely: (1) the yield of nitrite from the decomposition of peroxynitrite shows a dependence on the peroxynitrite concentration and is lower than expected for homolysis; (2) the yield of [15N]nitrate from the reaction of [15N]nitrite with Peroxynitrous Acid predicted by homolysis does not correspond to that found experimentally, and (3) the reaction of Peroxynitrous Acid with monohydroascorbate does not yield ascorbyl radicals. Activation volumes determined from high-pressure kinetic studies are inconclusive. IUBMB Life, 55: 567-572, 2003
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Rapid scavenging of Peroxynitrous Acid by monohydroascorbate.
Free radical biology & medicine, 2003Co-Authors: Christophe Kurz, Reinhard Kissner, Thomas Nauser, Daniel Perrin, Willem H. KoppenolAbstract:Abstract The reaction of Peroxynitrous Acid with monohydroascorbate, over the concentration range of 250 μM to 50 mM of monohydroascorbate at pH 5.8 and at 25°C, was reinvestigated and the rate constant of the reaction found to be much higher than reported earlier (Bartlett, D.; Church, D. F.; Bounds, P. L.; Koppenol, W. H. The kinetics of oxidation of L-ascorbic Acid by peroxynitrite. Free Radic. Biol. Med. 18: 85–92; 1995; Squadrito, G. L.; Jin, X.; Pryor, W. A. Stopped-flow kinetics of the reaction of ascorbic Acid with peroxynitrite. Arch. Biochem. Biophys. 322: 53–59; 1995). The new rate constants at pH 5.8 are k 1 = 1 × 10 6 M −1 s −1 and k −1 = 500 s −1 for 25°C and k 1 = 1.5 × 10 6 M −1 s −1 and k −1 = 1 × 10 3 s −1 for 37°C. These values indicate that even at low monohydroascorbate concentrations most of Peroxynitrous Acid forms an adduct with this antioxidant. The mechanism of the reaction involves formation of an intermediate, which decays to a second intermediate with an absorption maximum at 345 nm. At low monohydroascorbate concentrations, the second intermediate decays to nitrate and monohydroascorbate, while at monohydroascorbate concentrations greater than 4 mM, this second intermediate reacts with a second monohydroascorbate to form nitrite, dehydroascorbate, and monohydroascorbate. EPR experiments indicate that the yield of the ascorbyl radical is 0.24% relative to the initial Peroxynitrous Acid concentration, and that this small amount of ascorbyl radicals is formed concomitantly with the decrease of the absorption at 345 nm. Thus, the ascorbyl radical is not a primary reaction product. Under the conditions of these experiments, no homolysis of Peroxynitrous Acid to nitrogen dioxide and hydroxyl radical was observed. Aside from monohydroascorbate's ability to “repair” oxidatively modified biomolecules, it may play a role as scavenger of Peroxynitrous Acid.
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Oxidation of Nitrite by Peroxynitrous Acid
The Journal of Physical Chemistry A, 2003Co-Authors: Patrick Maurer, Chris F. Thomas, Reinhard Kissner, Heinz Rüegger, Oswald Greter, † Ursula Röthlisberger, Willem H. KoppenolAbstract:The kinetics of the oxidation of nitrite to nitrate by Peroxynitrous Acid at pH 5.2 is best described by the rate law kobs = kiso + k‘[NO2-] + k‘ ‘[NO2-]2, in which the Peroxynitrous Acid isomerization rate constant kiso = (1.10 ± 0.05) s-1, k‘ = (3.2 ± 0.1) M-1 s-1, and k‘ ‘ = (4.2 ± 0.3) M-2s-1, at 25 °C. The ternary reaction may involve initial formation of an adduct between nitrite and peroxynitrite, followed by reaction with a second nitrite to form two nitrite and a nitrate. Ab initio calculations indicate that there is only a small intrinsic barrier to the net transfer of HO+ from Peroxynitrous Acid to the nitrogen atom of nitrite. A similar transfer to either of the two oxygens of nitrite produces the reactants, and would not lead to an increase in the rate of disappearance of Peroxynitrous Acid, as observed. The low rate constant is most likely due to stringent orientational constraints. Formal transfer of HO+ to 15NO2- results in formation of 15NO3-, as experimentally observed. HO+ transfer is c...
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Peroxynitrous Acid--where is the hydroxyl radical?
IUBMB life, 2003Co-Authors: Reinhard Kissner, Thomas Nauser, Christophe Kurz, Willem H. KoppenolAbstract:Peroxynitrite is an inorganic toxin of physiological interest, formed from the diffusion-controlled reaction of superoxide and nitrogen monoxide with a rate constant of (1.6 +/- 0.3) x 10(10) M(-1) s(-1). On the basis of three experiments we conclude that homolysis of the O-O bond in Peroxynitrous Acid is unlikely: (1) the yield of nitrite from the decomposition of peroxynitrite shows a dependence on the peroxynitrite concentration and is lower than expected for homolysis; (2) the yield of [15N]nitrate from the reaction of [15N]nitrite with Peroxynitrous Acid predicted by homolysis does not correspond to that found experimentally, and (3) the reaction of Peroxynitrous Acid with monohydroascorbate does not yield ascorbyl radicals. Activation volumes determined from high-pressure kinetic studies are inconclusive.
Michael J. Davies - One of the best experts on this subject based on the ideXlab platform.
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cross linking and modification of fibronectin by Peroxynitrous Acid mapping and quantification of damage provides a new model for domain interactions
Journal of Biological Chemistry, 2021Co-Authors: Michele Mariotti, Per Hägglund, Adelina Rogowskawrzesinska, Michael J. DaviesAbstract:Abstract Fibronectin (FN) is an abundant glycoprotein found in plasma and the extracellular matrix (ECM). It is present at high concentrations at sites of tissue damage, where is it exposed to oxidants generated by activated leukocytes, including Peroxynitrous Acid (ONOOH) formed from nitric oxide (from inducible nitric oxide synthase) and superoxide radicals (from NADPH oxidases and other sources). ONOOH reacts rapidly with the abundant tyrosine and tryptophan residues in ECM proteins, resulting in the formation of 3-nitroTyr, di-tyrosine, and 6-nitrotryptophan (6-nitroTrp). We have shown previously that human plasma fibronectin is readily modified by ONOOH, but the extent and location of modifications, and the role of fibronectin structure (compact versus extended) in determining these factors is poorly understood. Here we provide a detailed LC-MS analysis of ONOOH-induced fibronectin modifications, including the extent of their formation and the sites of intra- and inter-molecular cross-links, including Tyr-Tyr, Trp-Trp and Tyr-Trp linkages. The localization of these cross-links to specific domains provides novel data on the interactions between different modules in the compact conformation of plasma FN, and allows us to propose a model of its unknown quaternary structure. Interestingly, the pattern of modifications is significantly different to that generated by another inflammatory oxidant, HOCl, in both extent and sites. The characterization and quantification of these modifications offers the possibility of the use of these materials as specific biomarkers of extracellular matrix modification and turnover in the many pathologies associated with inflammation-associated fibrosis.
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Peroxynitrous Acid (ONOOH) modifies the structure of anastellin and influences its capacity to polymerize fibronectin.
Redox biology, 2020Co-Authors: Eva Ramos Becares, Michael J. Davies, Peter W. Thulstrup, Luke F. Gamon, Jannik Nedergaard Pedersen, Daniel E. Otzen, Pontus Gourdon, Per HägglundAbstract:Anastellin (AN), a fragment of the first type III module in fibronectin (FN), initiates formation of superfibronectin, a polymer which resembles the native cell-derived fibrillar FN found in the extracellular matrix of many tissues, but which displays remarkably different functional properties. Here we demonstrate that exposure of AN to the biologically-important inflammatory oxidant, Peroxynitrous Acid (ONOOH), either as a bolus or formed at low levels in a time-dependent manner from SIN-1, impairs the capability of AN to polymerize FN. In contrast, exposure of FN to ONOOH does not seem to affect superfibronectin formation to the same extent. This oxidant-induced loss-of-function in AN occurs in a dose-dependent manner, and correlates with structural perturbations, loss of the amino Acid tyrosine and tryptophan, and dose-dependent formation of modified amino Acid side-chains (3-nitrotyrosine, di-tyrosine and 6-nitrotryptophan). Reagent ONOOH also induces formation of oligomeric species which decrease in the presence of bicarbonate, whereas SIN-1 mainly generates dimers. Modifications were detected at sub-stoichiometric (0.1-fold), or greater, molar excesses of oxidant compared to AN. These species have been localized to specific sites by peptide mass mapping. With high levels of oxidant (>100 times molar excess), ONOOH also induces unfolding of the beta-sheet structure of AN, thermal destabilization, and formation of high molecular mass aggregates. These results have important implications for the understanding of FN fibrillogenesis in vivo, and indicates that AN is highly sensitive to pathophysiological levels of oxidants such as ONOOH.
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Exposure of tropoelastin to Peroxynitrous Acid gives high yields of nitrated tyrosine residues, di-tyrosine cross-links and altered protein structure and function.
Free radical biology & medicine, 2017Co-Authors: Georg Degendorfer, Christine Y. Chuang, Astrid Hammer, Ernst Malle, Per Hägglund, Michele Mariotti, Gerald Hoefler, Steven G. Wise, Michael J. DaviesAbstract:Elastin is an abundant extracellular matrix protein in elastic tissues, including the lungs, skin and arteries, and comprises 30-57% of the aorta by dry mass. The monomeric precursor, tropoelastin (TE), undergoes complex processing during elastogenesis to form mature elastic fibres. Peroxynitrous Acid (ONOOH), a potent oxidising and nitrating agent, is formed in vivo from superoxide and nitric oxide radicals. Considerable evidence supports ONOOH formation in the inflamed artery wall, and a role for this species in the development of human atherosclerotic lesions, with ONOOH-damaged extracellular matrix implicated in lesion rupture. We demonstrate that TE is highly sensitive to ONOOH, with this resulting in extensive dimerization, fragmentation and nitration of Tyr residues to give 3-nitrotyrosine (3-nitroTyr). This occurs with equimolar or greater levels of oxidant and increases in a dose-dependent manner. Quantification of Tyr loss and 3-nitroTyr formation indicates extensive Tyr modification with up to two modified Tyr per protein molecule, and up to 8% conversion of initial ONOOH to 3-nitroTyr. These effects were modulated by bicarbonate, an alternative target for ONOOH. Inter- and intra-protein di-tyrosine cross-links have been characterized by mass spectrometry. Examination of human atherosclerotic lesions shows colocalization of 3-nitroTyr with elastin epitopes, consistent with TE or elastin modification in vivo, and also an association of 3-nitroTyr containing proteins and elastin with lipid deposits. These data suggest that exposure of TE to ONOOH gives marked chemical and structural changes to TE and altered matrix assembly, and that such damage accumulates in human arterial tissue during the development of atherosclerosis.
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Peroxynitrous Acid induces structural and functional modifications to basement membranes and its key component, laminin.
Free radical biology & medicine, 2015Co-Authors: Georg Degendorfer, Christine Y. Chuang, Astrid Hammer, Ernst Malle, Michael J. DaviesAbstract:Basement membranes (BM) are specialized extracellular matrices underlying endothelial cells in the artery wall. Laminin, the most abundant BM glycoprotein, is a structural and biologically active component. Peroxynitrous Acid (ONOOH), a potent oxidizing and nitrating agent, is formed in vivo at sites of inflammation from superoxide and nitric oxide radicals. Considerable data supports ONOOH formation in human atherosclerotic lesions, and an involvement of this oxidant in atherosclerosis development and lesion rupture. These effects may be mediated, at least in part, via extracellular matrix damage. In this study we demonstrate co-localization of 3-nitrotyrosine (a product of tyrosine damage by ONOOH) and laminin in human atherosclerotic lesions. ONOOH-induced damage to BM was characterized for isolated murine BM, and purified murine laminin-111. Exposure of laminin-111 to ONOOH resulted in dose-dependent loss of protein tyrosine and tryptophan residues, and formation of 3-nitrotyrosine, 6-nitrotryptophan and the cross-linked material di-tyrosine, as detected by amino Acid analysis and Western blotting. These changes were accompanied by protein aggregation and fragmentation as detected by SDS-PAGE. Endothelial cell adhesion to isolated laminin-111 exposed to 10 μM or higher levels of ONOOH was significantly decreased (~25%) compared to untreated controls. These data indicate that laminin is oxidized by equimolar or greater concentrations of ONOOH, with this resulting in structural and functional changes. These modifications, and resulting compromised cell-matrix interactions, may contribute to endothelial cell dysfunction, a weakening of the structure of atherosclerotic lesions, and an increased propensity to rupture.
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Laminin, a key component of tissue extracellular matrix, is a major target for Peroxynitrous Acid
Free Radical Biology and Medicine, 2015Co-Authors: Georg Degendorfer, Christine Y. Chuang, Astrid Hammer, Ernst Malle, Michael J. DaviesAbstract:Basement membranes (BM) are specialized extracellular matrices underlying endothelial cells in the artery wall. Laminin, the most abundant BM glycoprotein, is a structural and biologically active component. Peroxynitrous Acid (ONOOH), a potent oxidizing and nitrating agent, is formed in vivo at sites of inflammation from superoxide and nitric oxide radicals. Considerable data supports ONOOH formation in human atherosclerotic lesions, and an involvement of this oxidant in atherosclerosis development and lesion rupture. These effects may be mediated, at least in part, via extracellular matrix damage. In this study we demonstrate co-localization of 3-nitrotyrosine (a product of tyrosine damage by ONOOH) and laminin in human atherosclerotic lesions. ONOOH-induced damage to laminin was characterized with purified murine laminin-111, and murine BM extracts containing multiple matrix components. Exposure of laminin-111 to ONOOH resulted in dose-dependent loss of protein tyrosine and tryptophan residues, and formation of 3-nitrotyrosine, 6-nitrotryptophan and the cross-linked material di-tyrosine, as detected by amino Acid analysis and Western blotting. This damage was modulated by bicarbonate, a known modifier of ONOOH reactions. These changes were accompanied by protein aggregation and fragmentation as detected by SDS-PAGE. Significant damage was detected with equimolar or greater concentrations of ONOOH. Endothelial cell adhesion to isolated laminin-111 was significantly decreased (~25%) compared to controls, on exposure to 10 μM or higher levels of ONOOH. These data indicate that laminin is oxidized by equimolar or greater concentrations of ONOOH, with this resulting in structural and functional changes. These modifications, and resulting compromised cell-matrix interactions, may contribute to endothelial cell dysfunction, a weakening of the structure of atherosclerotic lesions, and an increased propensity to rupture.
Xianglei Cheng - One of the best experts on this subject based on the ideXlab platform.
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Diversity of chemiluminescence from fluoroquinolones in the presence of Peroxynitrous Acid
Journal of Photochemistry and Photobiology A: Chemistry, 2016Co-Authors: Lijun Wei, Jing Liu, Hongcheng Liu, Tong Zhou, Hongping Cai, Xianglei ChengAbstract:Abstract In this article, eight fluoroquinolone analogs showed intriguing chemiluminescence (CL) diversity in the presence of Peroxynitrous Acid. Compared to current literature, these studied fluoroquinolones exhibit many novel characteristics on CL spectra, CL quantum yield and reaction routes. Furthermore, when the distribution of CL was comparable to its fluorescence, a diversity of differences between the analogs were observed. These results indicate that the hydroxyl radical OH and excited state Peroxynitrous Acid may account for these observations. This discovery could deepen the understanding of mechanisms in CL systems and change the traditional theories about CL phenomena.
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chemiluminescence parameters of Peroxynitrous Acid in the presence of short chain alcohols and ru bpy 32
Chemical Papers, 2011Co-Authors: Lijun Wei, Tong Zhou, Huifen Xia, Zhaopin Wang, Ping Yuan, Baojun Zhang, Xianglei ChengAbstract:The chemiluminescence behaviour and mechanism of Peroxynitrous Acid and Ru(bpy) 3 2+ were studied in the presence of short-chain alcohols (methanol, ethanol, propan-1-ol, propan-2-ol, butanol, 2-methylpropan-1-ol, pentanol). It was found that the chemiluminescence intensity of Peroxynitrous Acid and Ru(bpy) 3 2+ system could be significantly enhanced by these seven short-chain alcohols. The maximum chemiluminescence wavelength of 608 nm of [Ru(bpy) 3 2+ ]* in the excited state was attributed to the reaction between Ru(bpy) 3 2+ and dihydroxyalkyl radicals which were generated during the redox course of Peroxynitrous Acid and alcohols. In addition, the chemiluminescence signals of the system presented depended largely on the solubility and branched-chain structure as well as the length of carbon chain. The analytical characteristics and parameters of the Peroxynitrous Acid/Ru(bpy) 3 2+ /alcohols chemiluminescence system were investigated under optimum conditions.
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Chemiluminescence parameters of Peroxynitrous Acid in the presence of short-chain alcohols and Ru(bpy)32+
Chemical Papers, 2011Co-Authors: Lijun Wei, Tong Zhou, Huifen Xia, Zhaopin Wang, Ping Yuan, Baojun Zhang, Xianglei ChengAbstract:The chemiluminescence behaviour and mechanism of Peroxynitrous Acid and Ru(bpy) 3 2+ were studied in the presence of short-chain alcohols (methanol, ethanol, propan-1-ol, propan-2-ol, butanol, 2-methylpropan-1-ol, pentanol). It was found that the chemiluminescence intensity of Peroxynitrous Acid and Ru(bpy) 3 2+ system could be significantly enhanced by these seven short-chain alcohols. The maximum chemiluminescence wavelength of 608 nm of [Ru(bpy) 3 2+ ]* in the excited state was attributed to the reaction between Ru(bpy) 3 2+ and dihydroxyalkyl radicals which were generated during the redox course of Peroxynitrous Acid and alcohols. In addition, the chemiluminescence signals of the system presented depended largely on the solubility and branched-chain structure as well as the length of carbon chain. The analytical characteristics and parameters of the Peroxynitrous Acid/Ru(bpy) 3 2+ /alcohols chemiluminescence system were investigated under optimum conditions.
Reinhard Kissner - One of the best experts on this subject based on the ideXlab platform.
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On the Chemical and Electrochemical One-Electron Reduction of Peroxynitrous Acid
The journal of physical chemistry. A, 2005Co-Authors: Christophe Kurz, Reinhard Kissner, Xiuqiong Zeng, Stefan Hannemann, Willem H. KoppenolAbstract:Peroxynitrous Acid was reduced by cathodic linear sweep voltammetry at a gold electrode and by iodide at pH 3.2 and 5.6. The cathodic reduction wave was identified by measuring its decay in time, which was the same as observed by optical spectroscopy. The iodide oxidation was followed by optical measurement of the triiodide formation. Both reductions show one-electron stoichiometry, with the product nαα = 0.23 ± 0.04 from the electrochemical experiments, in which α is the transfer coefficient and nα the number of electrons transferred, and an diiodine yield of ca. 0.5 equiv per equivalent of Peroxynitrous Acid. The voltammetric reduction was irreversible up to scan rates of 80 V s-1. Both reductions were pH independent in the range studied. The voltammetric reduction is most likely an irreversible elemental reaction followed by a chemical decay that cannot be observed directly. Because of the pH independence, we conclude that both reductions have a common short-lived intermediate, namely [HOONO]•-. We est...
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Peroxynitrous Acid--where is the hydroxyl radical?
IUBMB Life, 2004Co-Authors: Reinhard Kissner, Thomas Nauser, Christophe Kurz, Willem H. KoppenolAbstract:Peroxynitrite is an inorganic toxin of physiological interest, formed from the diffusion-controlled reaction of superoxide and nitrogen monoxide with a rate constant of (1.6 ± 0.3) × 1010 M - 1 s - 1. On the basis of three experiments we conclude that homolysis of the O-O bond in Peroxynitrous Acid is unlikely: (1) the yield of nitrite from the decomposition of peroxynitrite shows a dependence on the peroxynitrite concentration and is lower than expected for homolysis; (2) the yield of [15N]nitrate from the reaction of [15N]nitrite with Peroxynitrous Acid predicted by homolysis does not correspond to that found experimentally, and (3) the reaction of Peroxynitrous Acid with monohydroascorbate does not yield ascorbyl radicals. Activation volumes determined from high-pressure kinetic studies are inconclusive. IUBMB Life, 55: 567-572, 2003
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Rapid scavenging of Peroxynitrous Acid by monohydroascorbate.
Free radical biology & medicine, 2003Co-Authors: Christophe Kurz, Reinhard Kissner, Thomas Nauser, Daniel Perrin, Willem H. KoppenolAbstract:Abstract The reaction of Peroxynitrous Acid with monohydroascorbate, over the concentration range of 250 μM to 50 mM of monohydroascorbate at pH 5.8 and at 25°C, was reinvestigated and the rate constant of the reaction found to be much higher than reported earlier (Bartlett, D.; Church, D. F.; Bounds, P. L.; Koppenol, W. H. The kinetics of oxidation of L-ascorbic Acid by peroxynitrite. Free Radic. Biol. Med. 18: 85–92; 1995; Squadrito, G. L.; Jin, X.; Pryor, W. A. Stopped-flow kinetics of the reaction of ascorbic Acid with peroxynitrite. Arch. Biochem. Biophys. 322: 53–59; 1995). The new rate constants at pH 5.8 are k 1 = 1 × 10 6 M −1 s −1 and k −1 = 500 s −1 for 25°C and k 1 = 1.5 × 10 6 M −1 s −1 and k −1 = 1 × 10 3 s −1 for 37°C. These values indicate that even at low monohydroascorbate concentrations most of Peroxynitrous Acid forms an adduct with this antioxidant. The mechanism of the reaction involves formation of an intermediate, which decays to a second intermediate with an absorption maximum at 345 nm. At low monohydroascorbate concentrations, the second intermediate decays to nitrate and monohydroascorbate, while at monohydroascorbate concentrations greater than 4 mM, this second intermediate reacts with a second monohydroascorbate to form nitrite, dehydroascorbate, and monohydroascorbate. EPR experiments indicate that the yield of the ascorbyl radical is 0.24% relative to the initial Peroxynitrous Acid concentration, and that this small amount of ascorbyl radicals is formed concomitantly with the decrease of the absorption at 345 nm. Thus, the ascorbyl radical is not a primary reaction product. Under the conditions of these experiments, no homolysis of Peroxynitrous Acid to nitrogen dioxide and hydroxyl radical was observed. Aside from monohydroascorbate's ability to “repair” oxidatively modified biomolecules, it may play a role as scavenger of Peroxynitrous Acid.
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Oxidation of Nitrite by Peroxynitrous Acid
The Journal of Physical Chemistry A, 2003Co-Authors: Patrick Maurer, Chris F. Thomas, Reinhard Kissner, Heinz Rüegger, Oswald Greter, † Ursula Röthlisberger, Willem H. KoppenolAbstract:The kinetics of the oxidation of nitrite to nitrate by Peroxynitrous Acid at pH 5.2 is best described by the rate law kobs = kiso + k‘[NO2-] + k‘ ‘[NO2-]2, in which the Peroxynitrous Acid isomerization rate constant kiso = (1.10 ± 0.05) s-1, k‘ = (3.2 ± 0.1) M-1 s-1, and k‘ ‘ = (4.2 ± 0.3) M-2s-1, at 25 °C. The ternary reaction may involve initial formation of an adduct between nitrite and peroxynitrite, followed by reaction with a second nitrite to form two nitrite and a nitrate. Ab initio calculations indicate that there is only a small intrinsic barrier to the net transfer of HO+ from Peroxynitrous Acid to the nitrogen atom of nitrite. A similar transfer to either of the two oxygens of nitrite produces the reactants, and would not lead to an increase in the rate of disappearance of Peroxynitrous Acid, as observed. The low rate constant is most likely due to stringent orientational constraints. Formal transfer of HO+ to 15NO2- results in formation of 15NO3-, as experimentally observed. HO+ transfer is c...
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Peroxynitrous Acid--where is the hydroxyl radical?
IUBMB life, 2003Co-Authors: Reinhard Kissner, Thomas Nauser, Christophe Kurz, Willem H. KoppenolAbstract:Peroxynitrite is an inorganic toxin of physiological interest, formed from the diffusion-controlled reaction of superoxide and nitrogen monoxide with a rate constant of (1.6 +/- 0.3) x 10(10) M(-1) s(-1). On the basis of three experiments we conclude that homolysis of the O-O bond in Peroxynitrous Acid is unlikely: (1) the yield of nitrite from the decomposition of peroxynitrite shows a dependence on the peroxynitrite concentration and is lower than expected for homolysis; (2) the yield of [15N]nitrate from the reaction of [15N]nitrite with Peroxynitrous Acid predicted by homolysis does not correspond to that found experimentally, and (3) the reaction of Peroxynitrous Acid with monohydroascorbate does not yield ascorbyl radicals. Activation volumes determined from high-pressure kinetic studies are inconclusive.
Horst Elias - One of the best experts on this subject based on the ideXlab platform.
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Fast Oxygen Atom Transfer from in Situ Generated Peroxynitrous Acid to Thiolato Sulfur Coordinated to Cobalt(III).
Inorganic chemistry, 1999Co-Authors: Stéphane Vayssié, Horst EliasAbstract:Peroxynitrous Acid, ON-OOH, a very powerful, but unstable oxidant, when generated in situ from H2O2 and HNO2, can rapidly oxidize thiolato sulfur in the cation [(en)2Co(SCH2CH2NH2)]2+ to form coordinated sulfenato sulfur in [(en)2Co(S{O}CH2CH2NH2)]2+.
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Fast Oxidation of Organic Sulfides by Hydrogen Peroxide by In Situ Generated Peroxynitrous Acid.
Angewandte Chemie (International ed. in English), 1998Co-Authors: Stéphane Vayssié, Horst EliasAbstract:A powerful oxidant and an unstable isomer of HNO3 , Peroxynitrous Acid ONOOH is generated by the fast reaction of H2 O2 with HNO2 in Acidic medium [Eq. (1)]. If sulfides R2 S are present, ONOOH sulfoxidizes them in minutes. This reaction occurs faster than the decay of ONOOH to HNO3 and allows the fast preparation of sulfoxides with H2 O2 . (1).