This product includes 150 ul of 10 x assay buffer (Buffer T4), 105 ul of 10 x concatenated DNA, 30 ul of 50 x ATP (10 mM),120 ul of 0.4 M EDTA, 160 ul of 20 x fluorescence dye and 20 spin columns for 20 DNA decatenation assays. The assay buffer is optimized for bacterial topoisomerase IV. Bacterial topoisomerase IV enzymes are provided separately.