Figure 6.
CPT resistance of Cs-TopIB on DNA relaxation. (A) Time courses assays were carried out from 1 to 30 min at 30°C in the presence of 5% DMSO or 50 mM of CPT and 200 ng of a negatively supercoiled pBR322. (B) Time courses assays were carried out from 1 to 30 min at 30°C in the presence of 5% DMSO or 50 mM of CPT and 200 ng of a positively supercoiled pBR322. Assays in (A) or (B) were done with addition of 10, 6 and 5 nM of Cs-TopIB, Hs-Top1mt and Hs-Top1 respectively. SC−: negatively supercoiled DNA; SC+: positively supercoiled DNA; R: relaxed DNA; C:control reaction without enzyme. Asterisk represents the open circular form in the control and a mix of the open form and the entirely relaxed form of the plasmids for the assays with enzymes.