S1 nuclease sensitivity to cis- and trans-diamminedichloro-platinum(II) modified DNAs: Influence of (G+C) content and nucleotide sequence

The sensitivity of S1 nuclease to cis- and trans-(NH sub(3)) sub(2)PtCl sub(2) modified DNAs is examined as a function of (1) the level of cis- and trans-(NH sub(3)) sub(2)PtCl sub(2) bound, (2) the % (G+C) content in DNA from different sources and (3) the sequence dependence in poly(dG) multiplied by poly(dC) and poly(dG-dC) multiplied by poly(dG-dC). The extent of DNA digested increases with increasing levels of either isomer and is inversely influenced by the % (G+C) content of the DNA. However, the difference in the extent of digestion between the cis- and trans-(NH sub(3)) sub(2)PtCl sub(2) modified DNAs at equivalent levels of bound isomer follows the order, calf-thymus . M. lysodeikticus) > poly(dG-dC) multiplied by poly(dG-dC).