This Kit is designed to assay any type II topoisomerase, either eu- or prokaryotic. Specifically, our Top2 Assay facilitates the purification and characterization of type II enzymes and contains all reagents necessary for routine assays of type II topoisomerases. The assay is based upon decatentation of kinetoplast DNA (kDNA) and because it is specific for type II activity (not type I), it can be carried out with crude cell extracts. Reaction products are resolved using a novel gel system that allows extremely rapid and unambiguous detection of topo II activity. The appropriate buffers, DNA substrates and DNA markers are included. The assay will detect poisons that stimulate DNA cleavage by topo II as well as agents that simply inhibit catalytic activity. The advantage of kDNA based assays is that the assays are fast and easy to allow activity guided purification of inhibitors from crude mixtures or extracts.