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. 2019 Feb 22;4(2):4049–4055. doi: 10.1021/acsomega.8b03428

Figure 4.

Figure 4

Inhibition of relaxation of plasmid DNA in the presence of increasing concentrations of fluoroquinolones. A: Plasmid DNA was incubated with ATP in the absence (−T) or presence (+T) of topoisomerase IIα (Top2A, top gel) or IIβ (Top2B, bottom gel). Reactions were performed with 10–300 μM of gemifloxacin (Gemi), ciprofloxacin (Cipro), or desethylene-ciprofloxacin (D-Cipro). Positions of relaxed (Rel) and supercoiled (SC) plasmid are shown on the left. Representative gels are shown, and experiments were performed at least three times. B: Structure of desethylene-ciprofloxacin. C: Quantified plasmid double-stranded DNA cleavage with topoisomerase IIα (Top2A) or IIβ (Top2B) in the presence of 30 μM etoposide (Etop, black bars) or 300 μM desethylene-ciprofloxacin (D-Cipro, red bars) is shown. Dotted line represents the level of DNA cleavage in the presence of DMSO. Error bars represent the standard deviation of three or more independent experiments.