用荧光光谱和共振光散射光谱研究甲硝唑与牛血清白蛋白的相互作用

用荧光光谱和共振光散射光谱对甲硝唑与牛血清白蛋白的作用进行了对比研究, 测定了该反应的结合常数、结合位点数. 探讨了甲硝唑对牛血清白蛋白荧光和共振光散射猝灭的机理． 利用热力学参数确定了分子间的作用力性质；根据非辐射能量转换机制, 确定了甲硝唑-牛血清白蛋白间的结合距离. 采用同步荧光技术考察了甲硝唑对牛血清白蛋白构象的影响．

Interaction of Metronidazole with Bovine Serum Albumin by Using Fluorescence and Resonance Light Scattering Spectra

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.