Fig 4. Polyamines regulate the in vitro activity of the purified DNA gyrases from S. Typhimurium and E. coli.

Topoisomerase-treated plasmid DNA was incubated with purified DNA gyrase alone (reference for 0% variation in DNA gyrase activity) and with the indicated amounts of each polyamine. The experiment was performed with the DNA gyrases from E. coli and (separately) from S. Typhimurium. DNA gyrase activity was calculated as ΔLk/hour from agarose/chloroquine gels and normalized to the activity of the purified DNA gyrase without polyamines. Coloured circles quantitatively represent added concentrations of putrescine (blue) or spermidine (green). Lowercase letters indicate pairwise statistical significance (Tukey’s HSD, p<0.05, n = 2).