This product includes 480 ul of 10 x Buffer, 405 ul of 10 x supercoiled plasmid DNA, 45 ul of 100 x E. coli topoisomerase IV, 420 ul of 10 mM ATP and 20 ul of 1500 x fluorescence dye H19 for 100 assays of DNA relaxation reactions in a 96-well assay format.