Studies on Escherichia coli X-Ray Endonuclease Specificity: Roles of Hydroxyl and Reducing Radicals in the Production of DNA Lesions

DNA strand breakage induced by X irradiation, by X irradiation and alkali treatment, or by X irradiation and subsequent incubation with Escherichia coli X-ray endonuclease was measured by the conversion of PM2 Type I DNA to Type II. The hydroxyl radical was found to mediate the formation of alkali-l...

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Bibliographic Details
Published in:Radiation research 1977-02, Vol.69 (2), p.328-338
Main Authors: Armel, Paul R., Strniste, Gary F., Wallace, Susan S.
Format: Article
Language:English
Subjects:
Alkalies
Binding Sites - drug effects
Binding Sites - radiation effects
Chemical bases
DNA
DNA - radiation effects
DNA damage
Endonucleases - pharmacology
Enzymes
Escherichia coli - enzymology
Free Radicals
Hydroxyl radicals
Hydroxylation
Irradiation
Lesions
Nucleic Acid Conformation - drug effects
Nucleic Acid Conformation - radiation effects
Osmium
Osmium - pharmacology
Oxidation-Reduction
Radiation damage
Space life sciences
Species Specificity
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Summary:DNA strand breakage induced by X irradiation, by X irradiation and alkali treatment, or by X irradiation and subsequent incubation with Escherichia coli X-ray endonuclease was measured by the conversion of PM2 Type I DNA to Type II. The hydroxyl radical was found to mediate the formation of alkali-labile lesions and to a lesser extent simple strand breaks. All alkali-labile lesions were found also to be enzyme-sensitive sites. In addition, when the effective concentration of hydroxyl radicals was reduced by radical scavenging, reducing species appeared to produce enzyme sensitive sites which were not alkali labile. Tryptone-glucose-yeast extract medium, which was used in an attempt to simulate cellular conditions, protected against strand breakage, alkali-labile lesions, and non-alkali-labile enzyme-sensitive damages. Last, the E. coli X-ray endonuclease recognized osmium tetroxide-induced DNA damages which are identical to the radiolysis products of thymine produced by ionizing radiation.
ISSN:0033-7587
1938-5404
DOI:10.2307/3574440