Spectroscopic studies on the binding of a new quinolone antibacterial agent: sinafloxacin to DNA.

The binding of sinafloxacin to DNA has been studied by fluorescence spectroscopy and UV-vis absorption spectroscopy. The variations in the spectroscopic characteristics of sinafloxacin upon addition of DNA were observed. Salt concentration effect, KI quenching, fluorescence polarization, DNA denaturation experiments, melting temperature (T(m)) curves and viscosity measurements were studied to investigate the binding mechanism. It was proved that the fluorescence quenching of sinafloxacin is a result of the formation of sinafloxacin-DNA complex. Quenching constants were determined using the Stern-Volmer equation. From the experiment evidence, the major binding mode of sinafloxacin with DNA was evaluated to be the groove binding.