A versatile mismatch recognition agent: Specific cleavage of a plasmid DNAat a single base mispair

[Rh(bpy)(2)(chrysi)](3+) is a novel, sterically bulky DNA intercalator that has been designed to bind specifically in the destabilized regions near DN A base mismatches and, upon photoactivation, to cleave the DNA backbone. He re the molecule is shown to be both a general and remarkably specific misma tch recognition agent. Specific DNA cleavage is observed at over 80% of mis match sites in all the possible single base pair sequence contexts around t he mispaired bases. Moreover, the complex is highly site-specific; it is sh own to recognize and photocleave at a single base mismatch in a 2725 base p air linearized plasmid heteroduplex. Sterically demanding intercalators suc h as [Rh(bpy)(2)(chrysi)](3+) may have application both in mutation detecti on systems and as mismatch-specific chemotherapeutic agents.