A New CoII Complex as a Bulge-Specific Probe for DNA.

Bulge cleavage of two or three bases occurs when a DNA substrate is specifically cleaved oxidatively by [CoII (tfa)2 (happ)] (see picture). Hydrogen peroxide is necessary for the activation of this octahedral complex, which suggests that hydroxyl radicals are the reactive species. The complex has no significant reactivity towards the corresponding sequence in a single-stranded DNA region, and it exhibits only a low affinity towards double-stranded DNA. happ=macrocyclic ligand based on 1,10-phenanthroline, tfa=trifluoroacetate.