On the Nature of Biochemically Generated Hydroxyl Radicals Studies using the Bleaching of p-Nitrosodimethylaniline as a Direct Assay Method

Studies using the Bleaching of p-Nitrosodimethylaniline as a Direct Assay Method

Authors

  • Wolf BORS,

    1. Abteilung für Strahlenbiologie, Institut für Biologie, Gesellschaft für Strahlen- und Umweltforschung mbH, Ingolstädter Landstraße 1, D-8042 Neuherberg, Federal Republic of Germany
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  • Christa MICHEL,

    1. Abteilung für Strahlenbiologie, Institut für Biologie, Gesellschaft für Strahlen- und Umweltforschung mbH, Ingolstädter Landstraße 1, D-8042 Neuherberg, Federal Republic of Germany
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  • Manfred SARAN

    1. Abteilung für Strahlenbiologie, Institut für Biologie, Gesellschaft für Strahlen- und Umweltforschung mbH, Ingolstädter Landstraße 1, D-8042 Neuherberg, Federal Republic of Germany
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Abstract

An efficient scavenger for radiolytically generated hydroxyl (OH) radicals, p-nitrosodimethyl-aniline, was used to try to substantiate the presence of this oxygen radical species in several biochemical systems. Most of these systems which were investigated had previously been assumed to generate OH radicals, e.g. the autoxidation of 6-hydroxydopamine, the hydroxylating system NADH/phenazine methosulfate, and the oxidation of xanthine or acetaldehyde by xanthine oxidase.

We did not observe inhibition of the bleaching of p-nitrosodimethylaniline in oxygenated solutions by other scavengers of OH radicals nor, in the case of xanthine/xanthine oxidase, by catalase and superoxide dismutase. We therefore conclude that, under biochemical conditions as opposed to radiolysis or photolysis, no freely diffusable OH radicals are formed. Rather, a strongly oxidizing OH-analogous complex is considered to represent the p-nitrosodimethylaniline-detectable species formed under these conditions.

Enzymes
 

Catalase (EC 1.11.1.6)

 

superoxide dismutase (EC 1.15.1.1)

 

xanthine oxidase (EC 1.2.3.2)

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