On the chemical reactivity of superoxide ion

Sawyer, Donald T.; Gibian, Morton J.; Morrison, Mark M.; Seo, Eddie T.

doi:10.1021/ja00470a046

Cited by 111 publications

(60 citation statements)

References 2 publications

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“…For example, the nearer E 1/2 value is that of the complex 1 which is observed at −0.660 instead of −0.622 V under nitrogen atmosphere. So, under the same experimental conditions and under oxygen atmosphere, the superoxide species are exclusively produced as reported by Sawyer et al [60]. For this reason, all the complexes 1, 2, and 3 (Table 1: E 1/2 < −750 mV) may be considered as catalysts activating the molecular oxygen like P450 cytochrome [18].…”

Section: Complexes Without Axialmentioning

confidence: 56%

“…Each of them shows a redox system at the cathodic potentials appearing before −0.75 V corresponding to the redox system of molecular oxygen [60]. In this case, we have only studied the Ru(III)/Ru(II) redox system according to the following equation: (2), and −0.507 V/SCE (3) These half-wave potentials (E 1/2 = (E pa − E pc )/2), involve E pa and E pc as potential values of oxidation and reduction waves of a redox couple.…”

Section: Complexesmentioning

confidence: 99%

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Synthesis, Characterization, and Electrochemical Study of Tetradentate Ruthenium‐Schiff Base Complexes: Dioxygen Activation with a Cytochrome P450 Model Using 1‐ or 2‐Methylimidazole as Axial Bases

Ourari

Khelafi

Aggoun

et al. 2011

Advances in Physical Chemistry

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Salicylaldehyde, 2-hydroxyacetophenone, and 3,5-dichlorosalicylaldehyde react with 1,2-diaminoethane to give three symmetrical Schiff bases H 2 L 1 , H 2 L 2 , and H 2 L 3 , respectively. With Ru(III) ions, these ligands lead to three complexes: Ru(III)ClL 1 (1), Ru(III)ClL 2 (2), and Ru(III)ClL 3 (3). The purity of these compounds was estimated by TLC technique and microanalysis while their structures were supported by the usual spectroscopic methods such as NMR, infrared, and electronic spectra. The cyclic voltammetry in acetonitrile showed irreversible waves for all three ligands. Under the same experimental conditions, it was proved that the ruthenium is coordinated in the three complexes 1, 2, and 3 showing quasireversible redox systems. The behavior of these complexes and their comparison with cytochrome P450 are investigated using them as catalysts in the presence of molecular oxygen with an apical nitrogen base: 1-or 2-methylimidazole.

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Section: Complexes Without Axialmentioning

confidence: 56%

Section: Complexesmentioning

confidence: 99%

Synthesis, Characterization, and Electrochemical Study of Tetradentate Ruthenium‐Schiff Base Complexes: Dioxygen Activation with a Cytochrome P450 Model Using 1‐ or 2‐Methylimidazole as Axial Bases

Ourari

Khelafi

Aggoun

et al. 2011

Advances in Physical Chemistry

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“…[27] was adjusted since the values reported therein are larger by approximately 0.2V than those from Refs. [23] and [19] for common compounds.…”

Section: Aro-h þ Coor ! Aroc þ H-oor ð1þmentioning

confidence: 99%

Unexpected Acid Catalysis in Reactions of Peroxyl Radicals with Phenols

et al. 2009

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Weak organic acids in millimolar concentrations increase the reactivity of peroxyl radicals with common phenolic antioxidants dramatically. This counterintuitive phenomenon relies on a substantially different reaction mechanism from that in the absence of an acid: rate‐determining electron transfer occurs from the hydrogen‐bonded phenol to the hydroperoxide cation radical present in equilibrium with the peroxyl radical under these conditions (see scheme).

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“…•-is essentially obligatory for this substrate to be amenable to reduction (26). Thus, one anticipates that O 2…”

Section: •-mentioning

confidence: 99%

“…•- (26). Moreover, the identities of the O atoms that receive H-bonds are important to the outcome of O 2…”

Section: Figurementioning

confidence: 99%

Anion Binding Properties of Reduced and Oxidized Iron-Containing Superoxide Dismutase Reveal No Requirement for Tyrosine 34

2005

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We report the first spectroscopic observation of substrate analogue binding to the reduced state of iron superoxide dismutase from Escherichia coli (Fe 2+ SOD) and demonstrate that the pH dependence reflects inhibition of anion binding by ionized Tyr34, not loss of a positive contribution on the part of Tyr34's labile proton. This can also explain the pH dependence of the K M of Fe 2+ SOD. Thus, it appears that substrate binding to Fe 2+ SOD occurs in the second sphere and is not strongly coupled to hydrogen bond donation. Parallel investigations of substrate analogue binding to the oxidized state (Fe 3+ SOD) confirm formation of a six-coordinate complex and resolve the apparent conflict with earlier nuclear magnetic relaxation dispersion (NMRD) results. Thus, we propose that two F -ions can bind to the oxidized Fe 3+ SOD active site, either displacing the coordinated solvent or lowering its exchange rate with bulk solvent. We show that neutral Tyr34's unfavorable effect on binding of the substrate analogue N 3 -can be ascribed to steric interference, as it does not apply to the smaller substrate analogues F -and OH -. Finally, we report the first demonstration that HS -can act as a substrate analogue with regard both to redox reactivity with FeSOD and to ability to coordinate to the active site Fe 3+ . Indeed, it forms a novel green complex. Thus, we have begun to evaluate the relative importance of different contributions that Tyr34 may make to substrate binding, and we have identified a novel, redox active substrate analogue that offers new possibilities for elucidating the mechanism of FeSOD.

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On the chemical reactivity of superoxide ion

Cited by 111 publications

References 2 publications

Synthesis, Characterization, and Electrochemical Study of Tetradentate Ruthenium‐Schiff Base Complexes: Dioxygen Activation with a Cytochrome P450 Model Using 1‐ or 2‐Methylimidazole as Axial Bases

Synthesis, Characterization, and Electrochemical Study of Tetradentate Ruthenium‐Schiff Base Complexes: Dioxygen Activation with a Cytochrome P450 Model Using 1‐ or 2‐Methylimidazole as Axial Bases

Unexpected Acid Catalysis in Reactions of Peroxyl Radicals with Phenols

Anion Binding Properties of Reduced and Oxidized Iron-Containing Superoxide Dismutase Reveal No Requirement for Tyrosine 34

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