Deoxyoligonucleotide chain cleavage reactions by phenanthroline and bleomycin

To elucidate the mechanisms of double-stranded DNA chain cleavage by 1,10-phenanthroline-Cu(I) and bleomycin-Fe(II) complexes in oxygen-dependent reactions, self-complementary deoxyoligonucleotides were treated with the complexes and the degradation products were characterized. The degradation products of d(C-G) by the phenanthroline complex were fully identified by UV, proton and carbon-13 NMR and paper electrophoresis. It is assumed that the DNA chain cleavage and concomitant base release are caused by oxidation of Cl' of the deoxyribose moiety. A duplex of d(ATACGCGTAT) was cleaved by both complexes. Bleomycin shows some sequence specificity but phenanthroline does not.