The Effect of Oxygen on the Radiolysis of Tyrosine in Aqueous Solutions

Čudina, I.; Josimović, Lj.

doi:10.2307/3576947

Cited by 37 publications

(17 citation statements)

References 20 publications

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“…It is assumed that in the presence of O 2 À the phenoxyl radicals are partially reduced to phenol, which causes the diminution of the initial degradation yield. Such electron transfer processes were reported previously for tyrosine (Cudina and Josimovic, 1987) and for the semiquinone radicals of catechol derivatives (Bors et al, 1979).…”

Section: Experiments In Tap Watersupporting

confidence: 82%

Degradation of catechol by ionizing radiation, ozone and the combined process ozone-electron-beam

Kubesch

Zona

Solar

et al. 2005

Radiation Physics and Chemistry

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Section: Experiments In Tap Watersupporting

confidence: 82%

Degradation of catechol by ionizing radiation, ozone and the combined process ozone-electron-beam

Kubesch

Zona

Solar

et al. 2005

Radiation Physics and Chemistry

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“…In tyrosine, the principal reaction product with HO • was 3,4-dihydroxyphenylalanine (dopa), regardless of the presence of dioxygen [57,58]. In the presence of dioxygen, the yields of dopa were equal to the loss of the amino acid and to the amount of HO • generated, demonstrating that dopa was virtually the sole stable product [59]. Analogous results were obtained with peptides of glycine and tryptophan, again showing that tryptophan was the main residue attacked.…”

Section: Generalmentioning

confidence: 82%

The kinetics of oxidation of GSH by protein radicals

Nauser

Koppenol

Gebicki

2005

Biochemical Journal

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Current studies provide evidence that proteins are initial targets of ROS (reactive oxygen species) in biological systems and that the damaged proteins can in turn damage other cell constituents. This study was designed to test the possibility that protein radicals generated by ROS can oxidize GSH and assess the probability of this reaction in vivo by measurement of the rate constant of this reaction. Lysozyme radicals were generated by hydroxyl and azide radicals in steady-state gamma ray radiolysis. In the absence of dioxygen, a range of protein carbon-centred amino acid radicals were produced by the hydroxyl radicals, and defined tryptophan radicals by the azide radicals. In the presence of dioxygen, each carbon-centred radical was converted to a protein peroxyl radical. Each of the peroxyl radicals was able to oxidize a molecule of GSH, regardless of its location in the protein. The peroxyl radicals were 10 and 20 times more effective GSH oxidants than the carbon-centred radicals produced randomly in the lysozyme, or the defined tryptophan lysozyme radicals respectively. We obtained for the first time the rate constant of reaction between a protein free-radical and GSH. Lysozyme tryptophan carbon radicals generated by nanosecond pulse radiolysis and flash photolysis oxidized GSH with a rate constant of (1.05+/-0.05)x10(5) M(-1) x s(-1). Overall, the results are consistent with the hypothesis that protein radicals may be important intermediates in the pathway linking oxidative stress and damage in living organisms and emphasize the strongly enhancing role of dioxygen in this process.

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“…Oxyhemoglobin-It has been reported that the protein radical formed in ferrylmyoglobin could decay (i) by tyrosine addition to the heme group, as described by Catalano et al (20) for myoglobin, (ii) by dityrosine crosslink formation as in sperm whale myoglobin (19), or (iii) by an oxygen addition to the aromatic radical in either hemoglobin or myoglobin (32,33). The latter mechanism, oxygen addition to the aromatic radical, would yield a peroxyl tyrosine radical, which could be proposed as the initial step in the formation of oxidation products.…”

Section: Mechanism Of Formation Of Tyrosine Oxidation Products and DImentioning

confidence: 99%

Mechanism of the Formation and Proteolytic Release of H2O2-induced Dityrosine and Tyrosine Oxidation Products in Hemoglobin and Red Blood Cells

Giulivi

Davies

2001

Journal of Biological Chemistry

113

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Oxyhemoglobin exposed to a continuous flux of H 2 O 2 underwent oxidative modifications, including limited release of fluorescent fragmentation products. The main fragments formed were identified as oxidation products of tyrosine, including dopamine, dopamine quinone, and dihydroxyindol. Further release of these oxidation products plus dityrosine was only seen after proteolytic degradation of the oxidatively modified hemoprotein. A possible mechanism is proposed to explain the formation of these oxidation products that includes cyclization, decarboxylation, and further oxidation of the intermediates. Release of dityrosine is proposed as a useful technique for evaluating selective proteolysis after an oxidative stress, because dityrosine is metabolically stable, and it is only released after enzymatic hydrolysis of the oxidatively modified protein. The measurement can be accomplished by high performance liquid chromatography with fluorescence detection or by high efficiency thin layer chromatography. Comparable results, in terms of dityrosine release, were obtained using red blood cells of different sources after exposing them to a flux of H 2 O 2 . Furthermore, dityrosine has been reported to occur in a wide variety of oxidatively modified proteins. These observations suggest that dityrosine formation and release can be used as a highly specific marker for protein oxidation and selective proteolysis.

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The Effect of Oxygen on the Radiolysis of Tyrosine in Aqueous Solutions

Cited by 37 publications

References 20 publications

Degradation of catechol by ionizing radiation, ozone and the combined process ozone-electron-beam

Degradation of catechol by ionizing radiation, ozone and the combined process ozone-electron-beam

The kinetics of oxidation of GSH by protein radicals

Mechanism of the Formation and Proteolytic Release of H2O2-induced Dityrosine and Tyrosine Oxidation Products in Hemoglobin and Red Blood Cells

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