Strand cleavage of supercoiled DNA by water-soluble peroxyl radicals. The overlooked importance of peroxyl radical charge

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DOIResolve DOI: http://doi.org/10.1021/bi991463o
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TypeArticle
Journal titleBiochemistry
ISSN0006-2960
Volume39
Issue14
Pages41294135; # of pages: 7
Subjectperoxy radical; article; cell protection; DNA cleavage; DNA degradation; DNA supercoiling; electricity; lipid peroxidation; nonhuman; oxygen saturation; priority journal; reaction analysis; reproducibility; solubilization; Animals; DNA; Electrostatics; Free Radicals; Humans; Nucleic Acid Conformation; Peroxides
AbstractIt is well established that the peroxyl radicals formed during the thermal decomposition of 2,2'-azobis(amidinopropane), ABAP, in oxygenated water can cleave double-stranded DNA, from which fact it has been concluded that peroxyl radicals, as a general class, can induce DNA strand scission. However, the ABAP-derived radicals are positively charged, and DNA is a negatively charged polyanion. Moreover, the relatively small and, therefore, free to diffuse peroxyl radicals likely to be formed in vivo will generally be negatively charged or neutral. Plasmid supercoiled DNA [pBR 322, 4361 base pairs (bp)] was reacted with known, equal fluxes of two positively charged peroxyl radicals, a negatively charged peroxyl radical, and a neutral peroxyl radical. The two positively charged peroxyl radicals degraded ≥80% of the supercoiled pBR 322 at a flux of 4 radicals/bp, but the negatively charged and neutral peroxyl radicals had no significant effect even at a flux as high as 24 radicals/bp. The same lack of effect on the DNA was also observed with high fluxes of superoxide/hydroperoxyl radicals. Similar results were obtained with another supercoiled DNA, pUC 19, except that pUC 19 is somewhat more sensitive to strand scission by positively charged peroxyl radicals than pBR 322. We conclude that most of the peroxyl radicals likely to be formed in vivo have little or no ability to induce DNA strand scission and that the potential role of electrostatics in radical/DNA reactions should always be considered.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada (NRC-CNRC); NRC Institute for Biological Sciences (IBS-ISB)
Peer reviewedYes
NPARC number21276763
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Record identifiere210776c-cbe7-45cb-baa0-27803af6237f
Record created2015-10-13
Record modified2016-05-09
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