荧光法研究二氧化硫衍生物与牛血清白蛋白的相互作用

Study on interaction between SO_2 derivative and bovine serum albumin by fluorescence spectrophotometry

目的:研究二氧化硫衍生物与牛血清白蛋白(BSA)的相互作用。方法:用荧光猝灭光谱法和紫外可见吸收光谱法分析BSA及BSA-二氧化硫衍生物相互作用后体系的光谱特征。结果:①在不同温度下,二氧化硫衍生物能使BSA的内源荧光发生有规律的猝灭,猝灭作用可能为静态猝灭。②得出了二氧化硫衍生物和BSA相互作用的热力学常数、结合常数和结合位点数;相互作用力主要为氢键和范德华力,且作用力较弱。③三维荧光光谱表明,二氧化硫衍生物对BSA的构象影响不明显。结论:二氧化硫衍生物与BSA可能的结合方式为二氧化硫衍生物与蛋白质的氨基酸残基发生结合反应,生成不发荧光或者荧光强度较弱的基态复合物,使BSA荧光发生部分猝灭,但对BSA构象影响不明显,具体作用机制还需进一步探讨。

Objective： To study the interaction between SO2 derivative and bovine serum albumin （BSA）. Methods： The spectral features of BSA and BSA-SO2 derivative system were observed by fluorescence spectrophotometry and ultraviolet absorbance spectrophotometry. Results： （1） At different temperatures, the fluorescence of BSA was quenched regularly by SO2 derivative and relevent dynamic constants were obtained. The quenching mechanism possibly belongs to static quenching. （2） The thermodynamic parameters, binding constants and number of binding sites at different temperatures were obtained. The binding forces between them are mainly hydrophobic and Van der Waals forces, but they are weak. （3） The influence of SO2 derivative on the structure of BSA is not obvious. Conclusion： The binding mechanism between SO2 derivative and BSA may be that the molecules of SO2 derivative entered the hydrophilic area of protein, then bound with tryptophan and produced ground state complexes with no or weak fluorescence, leading to the partial quenching of the fluorescence of BSA. The mechanism needs further study.