Oxygen is not required for degradation of DNA by glutathione and Cu(II)

Previous studies by others have shown that thiols, such as glutathione, cause cleavage of DNA in the presence of Cu(II) ions and that the hydroxyl radical derived from molecular oxygen is the major cleaving species. In this paper, we present several lines of evidence that strongly suggest that molecular oxygen is not essential for DNA cleavage and that thiyl radicals may also be involved. Indirect evidence is presented to indicate that glutathione may substitute oxygen as an electron acceptor. In addition, DNA degradation occurs to a significant extent under anaerobic conditions and no inhibition of single-strand cleavage of supercoiled plasmid DNA is seen in the presence of superoxide dismutase and catalase. In view of the ubiquitous presence of glutathione, these results could be of interest under certain diseased conditions where copper concentrations are elevated.