Complex sentence: The potency of novobiocin is considerably higher than that of the fluoroquinolones that also target DNA gyrase but at a different site on the enzyme the GyrA subunit involved in the DNA nicking and ligation activity.
Split into simpler sentences: The potency of novobiocin is considerably higher than that of the fluoroquinolones that also target DNA gyrase, but at a different site on the enzyme. The GyrA subunit is involved in the DNA nicking and ligation activity.