Degradation of Nucleic Acid in Aqueous Solution by Ionizing Radiation. I. Loss of Ultra-violet Absorption of Solutions of Thymine or Thymine Derivatives on X-irradiation

De, Hoard; Fn, Hayes; Wb, Goad

doi:10.1080/09553007414550801

Cited by 2 publications

(1 citation statement)

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“…Both direct and indirect effects involving radiation processes cause strand breaks and base modifications of cellular DNA which are potentially a causative factor in carcinogenesis, mutagenesis, lethal cellular lesions, and a variety of human diseases. As a broad feature, the OH radical reactions of free nucleoside or nucleotide are classified as hydrogen atom abstraction from the 2-deoxyribose moieties (∼20%), leading to DNA strand breaks, and attacks on the base constituents (∼80%), leading to their modification …”

Section: Introductionmentioning

confidence: 99%

OH Radical Reaction of 5-Substituted Uracils: Pulse Radiolysis and Product Studies of a Common Redox-Ambivalent Radical Produced by Elimination of the 5-Substituents

et al. 2001

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Using a redox titration method in the pulse radiolysis of N 2 O-saturated phosphate buffer solution, the redox properties of the intermediate radicals derived from OH radical reactions of 5-substituted uracils 1c-h (R ) F, Cl, Br, NO 2 , NH 2 , OH) have been characterized. While the primary intermediates were oxidizing C(5) radicals 2c-h and reducing C(6) radicals 3c-h of the respective OH adducts, a common allyl-type radical of "redox ambivalence" with limiting mesomeric forms of reducing carbon-centered 5-oxo-5,6-dihydrouracil-6-yl radical (4) and oxidizing oxygen-centered uracil-5-oxyl radical (5) was secondarily formed via elimination of 5-substituents from 3c-h. The rate of 5-substituent elimination decreased with varying structures of the 5-substituents in the order halo > amino, nitro > hydroxy groups. The common radical 4/5 showed weaker reducing/oxidizing abilities than the typical pyrimidine C(6) and C(5) radicals. The product study demonstrated that the one-electron reduction of 5-oxyl radical 5 by N,N,N′,N′-tetramethyl-p-phenylenediamine ((2.0 ( 0.1) × 10 8 dm 3 mol -1 s -1 ) increased the yield of isobarbituric acid (1h), while the one-electron oxidation of 5-oxo C(6) radical 4 by tetranitromethane increased the yield of isodialuric acid (6).

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Section: Introductionmentioning

confidence: 99%