Studies on Horseradish Peroxidase. XII. A Kinetic Study of the Oxidation of Sulfite and Nitrite by Compounds I and II

Roman, R.; Dunford, H. Brian

doi:10.1139/v73-089

Cited by 75 publications

(36 citation statements)

References 11 publications

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“…1A). The calculated value of 1.04 ± 0.04 × 10 3 M −1 s −1 at pH 7.4 is over 10-fold faster than that reported for HRP-compound I and sulfite (7.6 ± 0.8 × 10 M −1 s −1 ) [30]. …”

Section: Resultsmentioning

confidence: 80%

Formation of reactive sulfite-derived free radicals by the activation of human neutrophils: An ESR study

Ranguelova

Rice

Khajo

et al. 2012

Free Radical Biology and Medicine

114

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The objective of the present study is to determine the effect of (bi)sulfite (hydrated sulfur dioxide) on human neutrophils and the ability of these immune cells to produce reactive free radicals due to (bi)sulfite oxidation. Myeloperoxidase (MPO) is an abundant heme protein in neutrophils that catalyzes the formation of cytotoxic oxidants implicated in asthma and inflammatory disorders. In the present study sulfite (•SO3−) and sulfate (SO4•−) anion radicals are characterized with the ESR spin-trapping technique using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) in the reaction of (bi)sulfite oxidation by human MPO and human neutrophils via sulfite radical chain reaction chemistry. After treatment with (bi)sulfite, PMA-stimulated neutrophils produced DMPO-sulfite anion radical, -superoxide, and -hydroxyl radical adducts. The latter adduct probably resulted, in part, from the conversion of DMPO-sulfate to DMPO-hydroxyl radical adduct via a nucleophilic substitution reaction of the radical adduct. This anion radical (SO4•−) is highly reactive and, presumably, can oxidize target proteins to protein radicals, thereby initiating protein oxidation. Therefore, we propose that the potential toxicity of (bi)sulfite during pulmonary inflammation or lung-associated diseases such as asthma may be related to free radical formation.

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“…1A). The calculated value of 1.04 ± 0.04 × 10 3 M −1 s −1 at pH 7.4 is over 10-fold faster than that reported for HRP-compound I and sulfite (7.6 ± 0.8 × 10 M −1 s −1 ) [30]. …”

Section: Resultsmentioning

confidence: 80%

Formation of reactive sulfite-derived free radicals by the activation of human neutrophils: An ESR study

Ranguelova

Rice

Khajo

et al. 2012

Free Radical Biology and Medicine

114

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“…The addition of nitrite did not significantly affect the ESR spectrum (Fig. 1C) (31). Only a weak, unrelated ESR signal was detected with HRP i alone (Fig.…”

Section: Direct Esr Detection Of the Tyrosyl Radical And The Tyrosinementioning

confidence: 83%

Tyrosine Iminoxyl Radical Formation from Tyrosyl Radical/Nitric Oxide and Nitrosotyrosine

Sturgeon

Glover

Chen

et al. 2001

Journal of Biological Chemistry

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Chem., 272, 17086 -17090). Although the iminoxyl radicals detected in the photosystem II and prostaglandin H synthase-2 systems strongly suggest a mechanism involving 3-nitrosotyrosine, the iminoxyl radical ESR spectrum was not unequivocally identified as originating from tyrosine. We report here the detection of the non-protein L-tyrosine iminoxyl radical generated by two methods: 1) peroxidase oxidation of synthetic 3-nitroso-N-acetyl-L-tyrosine and 2) peroxidase oxidation of free L-tyrosine in the presence of nitric oxide. A newly developed ESR technique that uses immobilized enzyme was used to perform the ESR experiments. Analysis of the high resolution ESR spectrum of the tyrosine iminoxyl radical generated from free tyrosine and nitric oxide reveals a 28.4-G isotropic nitrogen hyperfine coupling and a 2.2-G proton hyperfine coupling assigned to the proton originally ortho to the phenoxyl oxygen.Protein-derived radicals play an important role in enzymatic catalysis (1). The tyrosyl radical has been identified in a number of enzyme systems including photosystem II (2, 3), ribonucleotide reductase (4, 5), prostaglandin H synthase (6), DNA photolyase (7,8), and bovine liver catalase (9). Modified tyrosyl radicals have been observed in galactose oxidase (10, 11) and cytochrome c oxidase (12). The reaction of a tyrosyl radical cofactor with nitric oxide has been shown to inhibit enzyme activity. When photosystem II is exposed to NO, the stable tyrosyl radical cofactor Y D ⅐ is reversibly quenched (13). In addition, NO reversibly quenches the redox-active Y Z ⅐ in manganese-depleted photosystem II and the S3 state (an exchangecoupled complex involving Y Z ⅐ ) in acetate-treated photosystem II (14). When ribonucleotide reductase is exposed to NO, enzymatic activity is diminished; in addition the tyrosyl radical cofactor that resides on the R2 subunit is reversibly quenched (15)(16)(17). These studies with photosystem II and ribonucleotide reductase provide important insights into the reactivity of the tyrosyl radical and NO but provide little information regarding the nature of the tyrosyl radical/NO interaction.Exposure of photosystem II to NO followed by illumination at 200 K results in the quenching of the tyrosyl radical and the formation of an additional radical species that was assigned by ESR 1 as the tyrosine iminoxyl radical (ϾCϭN-O ⅐ ) based on the large nitrogen hyperfine-coupling constant (A iso ϭ 29.3 G) (18). When prostaglandin H synthase-2 is exposed to NO, the tyrosyl radical associated with enzymatic turnover is eliminated, and an additional radical species, similar to the one seen during the NO exposure/illumination in photosystem II, is detected. This radical is also assigned to the tyrosine iminoxyl radical (19,20). The observation of the tyrosine iminoxyl radical species in photosystem II and prostaglandin H synthase-2 prompted the proposal of Scheme 1.The reaction between tyrosyl radical (Scheme 1, A) and NO is near diffusion limited (1-2 ϫ 10 9 M Ϫ1 s Ϫ1 ) (21); a major product is expected t...

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“…[7] cthich gace a best fit to the experiinental data ~vith the parameter values given in Table 4. The rnodel seems equally appropriate in both H 2 0 and D 2 0 .…”

Section: Recrctions O F Cornpo~rnd~s I and 11 ~Citlz Frrr~ocj~rmiu'imentioning

confidence: 99%

Horseradish peroxidase. XXIX. Reactions in water and deuterium oxide: cyanide binding, compound I formation, and reactions of compounds I and II with ferrocyanide

Dunford¹,

Hewson²,

Steiner³

1978

Can. J. Chem.

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The kinetics of the reactions of hydrogen peroxide and cyanide with native horseradish peroxidase, as me11 as reactions of compounds I and IT with ferrocyanide have been studied in ordinary water and in deuteriuni oxide at 25'C and ionic strength 0.1 1 \:sing a stopped-flow apparatus. Rate constants for all reactions were measurcd over a wide range of acidity in both solvents from which equilibriunl and kinetic isotope effccts \\ere evaluated. Protonation of an ionizable group on the enzyme with a pK., value of 4.15 r 0.05 in ~vater inhibits the reactions with both hydrogen peroxide and cyanide. A significant kinetic isotope effect, k,, k , = 1.6 i 0.1, mas measured for compound 1 formation ahcreai no significant kinetic isotcpe effect was found for cyanide binding. On the basis of these findings, a partial niechanisn~ for compound 1 formation is proposed in which the group of pK, 4.15 plays a crucial role. The pH dependencies of the ferrocyanide reaction in the pH interval 4.5-10.8 confirnled the role of an acid group with a pK, of5.2 for compound I and for compound 11 a pK, of 8.6 and another with a val~ie loner than that encolupassed hy the pH range of the study. Eq~lilibri~lm isotope effects Mere found but no kinetic isotope effects for either the reaction of compound I or of compound 11. This suggests that there are no rate-limiting proton transfers in the reactions between ferrocyanide and compounds I and 11 of horseradish peroxidase. The only redcrcing substrates which cvhihit positive I<,, k , values possess a labile proton. H. BRIAU UL\FORD, W. DO\ALD HLWSON et HXKAN S T~I \~R .Can. j. Chem. 56.2844Chem. 56. (1978 Faisaat appel B un appareil B flux stoppi., on a Ctudie la cinetique des reactions du peroxyde

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Studies on Horseradish Peroxidase. XII. A Kinetic Study of the Oxidation of Sulfite and Nitrite by Compounds I and II

Cited by 75 publications

References 11 publications

Formation of reactive sulfite-derived free radicals by the activation of human neutrophils: An ESR study

Formation of reactive sulfite-derived free radicals by the activation of human neutrophils: An ESR study

Tyrosine Iminoxyl Radical Formation from Tyrosyl Radical/Nitric Oxide and Nitrosotyrosine

Horseradish peroxidase. XXIX. Reactions in water and deuterium oxide: cyanide binding, compound I formation, and reactions of compounds I and II with ferrocyanide

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