Spectroscopic studies on the interaction of pazufloxacin with calf thymus DNA

Fluorescence spectra, absorption spectra, DNA viscosity titrations, competition experiment, and iodide quenching experiment were used to study the interaction of DNA with pazufloxacin. DNA quenches the fluorescence of pazufloxacin significantly. No red shift and isobestic points are observed in UV titration experiment. DNA viscosity and iodide quenching results suggest that pazufloxacin does not intercalate into DNA. SsDNA has a stronger quenching effect on pazufloxacin than dsDNA has. Pazufloxacin interacts with DNA in a different mode from ethidium bromide, which is a typical intercalator of DNA. All these results indicate that pazufloxacin interacts with calf thymus DNA in the mode of groove binding. The quenching constant and thermodynamic constants have also been determined.