荧光猝灭法研究大黄酚与牛血清白蛋白的相互作用

Investigation of Interaction between Chrysophanol and Bovine Serum Albumin by Fluorescence Quenching Method

目的:运用荧光猝灭光谱研究了模拟人体生理条件下大黄酚与牛血清白蛋白(BSA)的相互作用。方法:以BSA为荧光剂,大黄酚为荧光猝灭剂,在激发波长278 nm下的荧光光谱,根据Stern-Volmer方程、位点结合模型和Lineweawer-Burk双倒数曲线方程,求出了大黄酚与BSA结合的结合类型、结合位点数和结合常数等参数。并利用Van’t Hoff方程求得反应的热力学参数,讨论了大黄酚与蛋白质的主要作用力类型。结果:大黄酚与BSA形成复合物从而猝灭BSA的内源荧光,且其荧光猝灭机理符合静态机制。在25℃和37℃下大黄酚与BSA结合的结合常数分别为:4.923×104 L.mol-1和5.928×104 L.mol-1;结合分子数分别为:0.8551和1.0583。热力学数据表明大黄酚与BSA以疏水作用为主,同时也存在较弱的静电作用。结论:大黄酚在体内能够被血清白蛋白存储和转运,且结合时可能改变了BSA的构象。

In present work,the interaction of chrysophanol with bovine serum albumin（BSA） under physiological condition was studied by fluorescence quenching spectra.The fluorescence was measured at 278 nm（excitation wavelength） with BSA as a fluorescence reagent,and Aloe-emodin as fluorescence quenching reagent.In addition,the drug-binding mode,binding constants,number of binding sites and thermodynamic parameters between chrysophanol and BSA were studied by Stern-Volmer equation,Lineweawer-Burk and Van＇t Hoff equation.The experiment demonstrated that chrysophanol has the ability to quench the intrinsic fluorescence of BSA because of its complex form.And the quenching mechanism is static quenching.At different temperatures（between 25℃ and 37℃）,the binding parameters of chrysophanol and bovine serum albumin were shown as： binding constants were 4.923×104 L·mol-1 and 5.928×104 L·mol-1;the number of binding sites were 0.8551 and 1.0583.The thermodynamic parameters showed that the interaction of them was driven mainly by hydrophobic force and electrostatic interaction.It is concluded that chrysophanol can be deposited and transported by serum protein in vivo.Besides,chrysophanol might have effect on the serum protein conformation.