Figure 3.

Comparison of the inhibition of the relaxation activity of hTopIB by 1 (left) and 2 (right). One unit hTopIB was assayed in a plasmid DNA relaxation assay for 30 min at 37 °C in the presence of 1–100 µM of either acids 1 or 2. Reaction products were resolved in agarose gel and subsequently visualized by ethidium bromide staining. The relative position of the negatively supercoiled DNA substrate is indicated by Sc, R is the relaxed DNA, whereas the ladder of relaxed DNA topoisomer bands is shown in between. Reactions were stopped with a mixture of 1% SDS and 6.1 µg of proteinase K. Lane 1 contains 0.5 µg of pSK plasmid DNA and lane 2, indicated by a 0, is 10% DMSO.