This product includes 300 ul of 10 x assay buffer, 200 ul of 10 x concatenated DNA (60 ug/ml), 200 ul of 10 x ATP, 20 ul of 100 x human topoisomerase II alpha, 300 ul of 10 x MgCl2 and 550 ul of 5 x gel-loading buffer for 100 assays of human DNA decatenation reactions.