Designed double-strand DNA cleavage with chelate-appended porphyrins

The first example of DNA double-strand cleavage mediated by a synthetic porphyrin is described. Two new porphyrins, each with two metal complexing appendages, were shown to mediate the oxidative double-strand cleavage of pBR322 plasmid DNA. By contrast, a porphyrin with one appendage was found to mediate only single-strand breaks.