Further evidence for double-strand breaks originating from a paired radical precursor from studies of oxygen fixation processes

Kevin Prise, N.E. Gillies, B.D. Michael

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

By using a fast reaction technique which employs H2S gas as a fast-reacting chemical repair agent, it is possible to measure the competition kinetics between chemical repair reactions and oxygen fixation reactions in model DNA and cellular systems. In plasmid pBR322 DNA irradiated with electrons, we have compared the oxygen fixation reactions of the free radical precursors that lead to the production of single-strand (SSBs) and double-strand breaks (DSBs). For the oxygen-dependent fixation of radical damage leading to SSBs, a second-order rate constant of 2.3 x 10(8) dm(3) mol(-1) s(-1) was obtained compared to 8.9 x 10(7) dm(3) mol(-1) s(-1) for DSBs. The difference is in general agreement with predictions from a multiple-radical model where the precursor of a DSB originates from two radicals. The fixation of this precursor by oxygen will require both radicals to be fixed for the DSB to be formed, which will have slower kinetics than that of single free-radical precursors of SSBs. (C) 1999 by Radiation Research Society.
Original languageEnglish
Pages (from-to)635-641
Number of pages7
JournalRadiation Research
Volume151
Issue number6
Publication statusPublished - Jun 1999

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Biophysics
  • Radiology Nuclear Medicine and imaging
  • Radiation

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