Selective Free Radical Reactions with Proteins and Enzymes: Reactions of Inorganic Radical Anions with Amino Acids

Adams, G. E.; Aldrich, John E.; Bisby, Roger H.; Cundall, R. B.; Redpath, J. L.; Willson, R. L.

doi:10.2307/3573266

Cited by 248 publications

(98 citation statements)

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“…•− and Br 2 •− had typical absorptions at around 340 and 360 nm, respectively [23,24]. In ionic liquids, the stabilization effect should be even stronger as a result of the smaller energy of solvation of the anions and the greater stabilization by large radical anions.…”

Section: Pulse Radiolysis Of Neat Ionic Liquidsmentioning

confidence: 99%

Pulse radiolysis studies of functionally substituted imidazolium-based ionic liquids

Zhang

Cao

et al. 2012

Chin. Sci. Bull.

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The reactions of imidazolium-based ionic liquids having different substituent groups on the ring with hydrated electrons (e − aq ), hydroxyl radicals (  OH), and sulfate anion radicals (SO 4 − ) were investigated using nanosecond pulse radiolysis techniques. The spectra of these ionic liquids on reaction with e aq − all exhibited a similar peak at about 320 nm, and a typical peak for e − aq in aqueous ionic liquid solutions. The reaction rate constants for 1,3-disubstituted imidazolium-based ionic liquid hexafluorophosphates (BMIPF 6 ) with e aq − were deduced to be 10 10 L mol −1 s −1 , however the values were lower for trisubstituted ionic liquids. For example, the rate constant for 1-butyl-2,3-dimethylimidazolium tetrafluoroborate (BMMIBF 4 ) was 5.5×10 9 L mol −1 s −1 . Imidazolium-based ionic liquids reacted with hydroxyl radicals via adducts to produce a mixture of isomeric OH adducts, and the pk a value of the OH adducts was deduced to be 8.4±0.4 for 1-butyl-3-methylimdazolium tetrafluoroborate (BMIBF 4 ). Moreover, imidazolium cations were also oxidized by SO 4 − to produce bivalent cation radicals, which exhibit a peak at 320 nm, and these rate constants are of the same order of magnitude, i.e., 10 9 L mol −1 s −1 , except that for 1-(2-hydroxyethyl)-3-methylimdazolium tetrafluoroborate with SO 4 − (k=2.8×10 8 L mol −1 s −1 ). Theoretical calculations were carried out to estimate the structures of the products of reduction by e aq − and the results were related to the experimental data.pulse radiolysis, imidazolium-based ionic liquids, kinetics, rate constants Citation:Fu H Y, Xing Z G, Cao X Y, et al. Pulse radiolysis studies of functionally substituted imidazolium-based ionic liquids.

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Section: Pulse Radiolysis Of Neat Ionic Liquidsmentioning

confidence: 99%

Pulse radiolysis studies of functionally substituted imidazolium-based ionic liquids

Zhang

Cao

et al. 2012

Chin. Sci. Bull.

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“…CO 3 . can participate in electron transfer reactions, addition, or hydrogen abstraction reactions (9,10). CO 3 .…”

Section: Oxidative Reactions Of Comentioning

confidence: 99%

“…CO 3 . , although less reactive than the hydroxyl radical, is a more selective oxidant that may diffuse over a longer distance, thereby causing oxidative damage to distant biological targets (9,10). We measured the peroxidase activity of SOD1 under anaerobic conditions by using the nitrite anion (NO 2 Ϫ ) as a peroxidase substrate (4).…”

mentioning

confidence: 99%

Bicarbonate Enhances the Peroxidase Activity of Cu,Zn-Superoxide Dismutase

Goss

Singh

Kalyanaraman

1999

Journal of Biological Chemistry

128

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“…Carbonate radical anion is the conjugate base of a strong acid (pK a Ͻ 0) (35) and a strong oxidant (36) with a characteristic spectrum in the visible (⑀ 600 ϭ 1860 M Ϫ1 cm Ϫ1 ) (32,33). Nevertheless, its reactivity is somewhat selective, and its potential targets in biological systems include sulfur-containing and aromatic amino acids (37,38).…”

mentioning

confidence: 99%

Reactions of Manganese Porphyrins with Peroxynitrite and Carbonate Radical Anion

Ferrer-Sueta

Vitturi

Batinić‐Haberle

et al. 2003

Journal of Biological Chemistry

159

208

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We have studied the reaction kinetics of ten manganese porphyrins, differing in their meso substituents, with peroxynitrite (ONOO ؊ ) and carbonate radical anion (CO 3 . ) using stopped-flow and pulse radiolysis, re- . by manganese porphyrins could occur in vivo because of the catalytic reduction at the expense of a number of cellular reductants. Additionally, we determined the pK a of the axial water molecules of the Mn(III) complexes at pH 7.5-13.2 by spectrophotometric titration. Results were consistent with two acid-base equilibria for most of the complexes studied. The pK a values also correlated with the resonance and inductive effects of the substituents. The correlations of E1 ⁄2 with the rate constants with ONOO ؊ and with the pK a values display a deviation from linearity when N-alkylpyridinium substituents included N-alkyl moieties longer than ethyl, which is interpreted in terms of a decrease in the local dielectric constant.Metalloporphyrins catalyze numerous redox reactions (1); in particular, manganese porphyrins have been used as redox catalysts in several model systems relevant to biochemistry, for instance, as superoxide dismutase (2, 3) and catalase (4) mimics. Some of the N-alkylpyridinium substituted complexes afforded protection of superoxide dismutase-deficient Escherichia coli from O 2 toxicity (5) and in several rodent models of transient brain ischemia (6, 7), diabetes (8), sickle cell disease (9), and radiation injury (10). Moreover, Mn III TCPP 1 has been effective in a number of model studies of oxidative stressmediated injury (for a review see Ref. 11) despite having low superoxide dismutase and catalase activities.Our group (12-14) and others (15) Given the ubiquity of CO 2 , its high concentration (1 to 2 mM in human tissues), and the reactivity of CO 3. (25), a useful peroxynitrite scavenger needs to out-compete the target molecules and CO 2 and/or be able to efficiently scavenge CO 3 . .We have proposed that complexes such as Mn III TM-2-PyP can efficiently inhibit peroxynitrite-mediated oxidations even in the presence of CO 2 (13). Moreover, the reaction of Mn III TM-2-PyP with ONOO Ϫ in the presence of CO 2 produced more oxidation of the metal complex than expected based on simple competition kinetics (13), suggesting a probable reaction of the complex with CO 3. . The possible reaction of Mn(III) porphyrins with CO 3 . has also been proposed recently (26) in experiments related to the effect of bicarbonate on the peroxidase activity of Cu,Zn superoxide dismutase. In aerated aqueous solution, the stable oxidation state of

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Selective Free Radical Reactions with Proteins and Enzymes: Reactions of Inorganic Radical Anions with Amino Acids

Cited by 248 publications

References 0 publications

Pulse radiolysis studies of functionally substituted imidazolium-based ionic liquids

Pulse radiolysis studies of functionally substituted imidazolium-based ionic liquids

Bicarbonate Enhances the Peroxidase Activity of Cu,Zn-Superoxide Dismutase

Reactions of Manganese Porphyrins with Peroxynitrite and Carbonate Radical Anion

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