Fig. 3

Inhibition of DNA gyrase-catalysed supercoiling by ciprofloxacin. a 1% agarose gel, stained with EtBr, showing plasmid pBR322 being supercoiled by DNA gyrase, and inhibition of this reaction by ciprofloxacin. DNA indicates relaxed DNA alone; +ve indicates gyrase only; all other tracks contain gyrase and the amounts of ciprofloxacin (in µM) indicated. b Electropherogram of the same samples as in (a); colours indicate the individual samples from (a). c Digital gel image of the same samples