Time-resolved EPR studies on the reaction rates of peroxyl radicals of poly(acrylic acid) and of calf thymus DNA with glutathione. Re-examination of a rate constant for DNA.
Electron paramagnetic resonance (EPR) signals of peroxyl radicals of poly(acrylic acid), PAA, and of single- and double-stranded DNA were generated at 293 K and pH 6.6 by in situ photolysis of O2-saturated aqueous solutions containing the macromolecules and H2O2. From time-resolved EPR measurements upper limits for the rate constants of reaction of glutathione (GSH) with the peroxyl radicals of PAA [kb < or = (0.8 +/- 0.2) x 10(2) dm3 mol-1S-1] and of single- and double-stranded DNA from calf thymus [kb < or = (2 +/- 2) x 10(2) dm3 mol-1S-1] were determined. The low value of kb for reaction of GSH with DNA peroxyl radicals is in agreement with the observed lack of protective effect of the thiol in radiation-induced DNA strand break reactions (Liphard et al. 1990).
Hildenbrand
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Max-Planck-Institut für Strahlenchemie, Mülheim a.d. Ruhr, Germany.
Schulte-Frohlinde
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D000180:Acrylic Resins; D000818:Animals; D002417:Cattle; D004247:DNA / Q000737:chemistry* / Q000528:radiation effects; D004249:DNA Damage; D004277:DNA, Single-Stranded / Q000737:chemistry*; D004228:Dithionitrobenzoic Acid; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D005978:Glutathione / Q000031:analogs & derivatives / Q000737:chemistry*; D019803:Glutathione Disulfide; D006861:Hydrogen Peroxide; D007700:Kinetics; D010084:Oxidation-Reduction; D010545:Peroxides; D013950:Thymus Gland; D013997:Time Factors
D000180:Acrylic Resins; D004277:DNA, Single-Stranded; D010545:Peroxides; C049375:perhydroxyl radical; C006903:carbopol 940; D004247:DNA; D004228:Dithionitrobenzoic Acid; D006861:Hydrogen Peroxide; D005978:Glutathione; D019803:Glutathione Disulfide