Abstract: By means of fluorescence and resonance light scattering spectrometries, the comparison of the interactions was made between metronidazole and bovine serum albumin(BSA). The apparent binding constant KA was found to be 2.22×104 L·mol-1 and the binding sits n to be 1.06±0.02 at 298 K by fluorescence quenching method. The quenching mechanism was discussed referring to metronidazole against the fluorescence and the resonance light scattering of BSA. The thermodynamic parameters of binding reaction were determined as follows: the molar change of enthalpy ΔrHm=6.42 kJ·mol-1, the molar change of Gibbs function ΔrGm=-23.0 kJ·mol-1, and the molar change of entropy ΔrSm=98.8 J·mol-1·K-1 at 298 K. The binding power between metronidazole and bovine serum albumin was also discussed. Furthermore, the binding distance of 3.16 nm was obtained between metronidazole and bovine serum albumin based on the mechanism of Forster non-radiation energy transfer. The effect of metronidazole on the conformation of BSA was analyzed by using the synchronous fluorescence spectroscopy.

Key words: Metronidazole, Bovine serum albumin, Fluorescence spectrum, Resonance rayleigh light scattering spectrum