Hydrogen peroxide lethality is associated with a decreased ability to maintain positive DNA supercoiling

Andrew T M Vaughan, D. J. Gordon

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Hydrogen peroxide is more toxic to mammalian cells at 37 °C than 0 °C at all concentrations studied. Histone-free nuclei (nucleoids) extracted from treated cells have a reduced ability to maintain positive DNA supercoiling, with the maximum effect at the higher temperature. Prior exposure of cells to sodium ascorbate at 0 °C increased both toxicity and the inhibition of nuclear supercoil rewinding. After exposure at 0 °C, normal levels of supercoiling returned with both a fast and a slow component, kinetics characteristic of DNA single-strand break repair; the fast component was eliminated when cells were exposed at 37 °C due to in situ rejoining. At least a portion of the lethal lesions induced by hydrogen peroxide are DNA double-strand breaks (dsb) because the dsb repair-deficient mutant, xrs-5, is approximately two to three times more sensitive than wild-type cells over the initial portion of the survival curve. However, the increased toxicity found after exposure at 37 °C is observed equally in both cell lines, indicating that temperature-dependent cell killing is not directly linked to DNA dsb. It is suggested that cell killing at 37 °C is mediated through two linked processes. First, hydrogen peroxide may disrupt cation-stabilized nuclear supercoiling by direct ion oxidation. Second, as a part of the oxidation process, hydrogen peroxide will produce potentially cytotoxic free radicals close to the DNA-linked metal site, limited in extent only by the presence of chemicals capable of reducing metal ions prior to reoxidation.

Original languageEnglish (US)
Pages (from-to)376-380
Number of pages5
JournalExperimental Cell Research
Issue number2
StatePublished - 1992
Externally publishedYes

ASJC Scopus subject areas

  • Cell Biology


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