Figure 4.

Inhibition of the catalytic activity of purified yeast DNA topoisomerase II by compounds 9, 14, 42 and 44 as measured by relaxation. Supercoiled pBR322 plasmid DNA (- TOPO II) was relaxed by purified yeast topoisomerase II in the absence (+ TOPO II) or presence of analyzed compounds 14, 42 and 44 at 1–150 μM concentrations or 1–50 μM for 9 (higher concentrations have not been tested due to the low solubility of the compound). The resulting topological forms of DNA were separated by gel electrophoreses. SC, supercoiled DNA; R, relaxed DNA; T, DNA topoisomers. Data shown are typical of three independent experiments and one set of representative pictures are shown. Original gels are presented in Supplementary Fig. S1.