Quinolone Interactions with DNA and DNA Gyrase

One of the most powerful methods for investigating the molecular mechanism of drug action is the use of radioligand binding technique. The method allows investigators to pinpoint the direct target of the drug, and the nature of the interaction in terms of binding affinity, specificity, and cooperativity as well as molar binding ratios. These parameters are crucial for deducing a mechanistic model for the drug’s action and thereby assist in the process of drug design by furthering our understanding of the established structure-activity relationship of that class of compounds. The method has been best exemplified by the investigations of mode of action of quinolone antibacterials that target the bacteria-specific type II DNA topoisomerase, DNA gyrase (reviewed in refs. 1 –5 ).