Mechanism of reduction of bleomycin-cu(II) by CO-2 and oxidation of bleomycin - cu(i) by h2o2 in the absence and presence of DNA

Sara Goldstein*, Gidon Czapski

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

The reduction reaction of bleomycin - Cu(II) by CO-2 has been studied by γ and pulse radiolysis at pH7. The CO-2 radical reduces bleomycin - Cu(II) at a rate of (6·7 ± 0·7) × 108 dm3 mol-1 s-1. In the presence of calf thymus DNA the rate of the reduction decreased as the concentration of DNA increased, indicating that the reduction reaction proceeds through free bleomycin - Cu(II). The stoichiometry and the kinetics of the oxidation of bleomycin - Cu(I) by H2O2 in the presence and absence of DNA have been studied. Our observations suggest that the OH· radical is not produced during this reaction and the degradation of the drug occurs in the absence and presence of DNA. We assume that bleomycin - Cu(II) in the presence of a reducing agent and molecular oxygen or H2O2 does not cleave DNA since the oxidizing species, which are formed during the oxidation reaction by H2O2, attack the drug even in the presence of DNA.

Original languageEnglish
Pages (from-to)693-706
Number of pages14
JournalInternational Journal of Radiation Biology
Volume51
Issue number4
DOIs
StatePublished - 1987

Keywords

  • Bleomycin
  • Copper
  • DNA damage
  • OH radical

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