Photoaddition of Ru(tap)sub2(bpy)super2+ to DNA: A new mode of covalent attachment of metal complexes to duplex DNA

The chemical nature of the species produced by the reaction of photooxidizing ruthenium(II) complexes with double-helical DNA is investigated. Photolysis of Ru(tap)sub2(bpy)super2+ in the presence of native (calf thymus) DNA formed products that were enzymatically excised. The photochemical reaction of RU(tap)sub3super2_ with guanosine 5'-monophosphate formed a covalent linkage between a tap ligand and the 2-NHsub2 guanine group.