Figure 7.

Effects of bis-3-chloropiperidine 1 on DNA integrity and decatenation by human topoisomerase IIα. Lane B contains kinetoplast DNA (kDNA) used as initial nucleic acid substrate. Lane C contains a mixture of kDNA and topoisomerase IIα (topo IIα) incubated for 1 h at 37°C (see Experimental Section for details). Lane 1, 2, and 3 contain kDNA samples treated respectively with 0.5, 5, and 50 μM of bis-3-chloropiperidine 1, which were incubated for 2 h at 37°C. Lane 1t, 2t, and 3t contain samples with the same compositions of those analyzed in Lane 1–3, which were further incubated with topo IIα for 1 h at 37°C. Lane 4–6 and 4t-6t contain samples analogous to those analyzed in Lane 1–3 and 1t-3t, which were instead reacted for 18 h prior to addition of topo IIα. To facilitate the interpretation, we included arrows to indicate the position of detected decatenated monomers; dashed arrow indicates the position of decatenated monomers migrating more slowly.