同步荧光光谱法结合分子对接研究金雀花碱与牛血清白蛋白间相互作用

金雀花碱(Cy)是一种生物碱，主要存在于豆科毒豆属植物种子中。Cy具有较强的生物活性，特别是作为戒烟药物已得到广泛应用。在模拟生理条件下，应用荧光光谱法研究了Cy同牛血清白蛋白(BSA)之间的相互作用以及Cy猝灭BSA荧光发射的机理。详细考查了水浴温度、水浴时间以及溶液pH等因素对荧光猝灭的影响，并且通过Stem-Volmer方程计算了Cy与BSA间的结合类型、结合位点数目以及结合常数。结果表明，Cy与BSA可形成摩尔比为1∶1的非共价复合物，其结合常数为5.6×103，其猝灭类型为静态猝灭。同步荧光光谱研究结果表明，Cy的结合主要影响BSA 的Trp残基的荧光发射。进一步应用分子对接研究表明，氢键与疏水作用是Cy与BSA形成复合物的主要推动力。Cy与BSA中Trp213及其周围的氨基酸残基间存在氢键与疏水作用，这种作用将改变Trp213所处微环境的疏水情况，从而导致BSA的荧光发生猝灭。

Intermolecular Interactions between Cytisine and Bovine Serum Albumin: A Synchronous Fluorescence Spectroscopic Analysis and Molecular Docking Research

Cytisine (Cy) is one of the alkaloids that exist naturally in the plant genera Laburnum of the family Fabaceae. With strong bioactivities, Cy is commercialized for smoking cessation for years. In this work, the study of intermolecular interactions between Cy and bovine serum albumin (BSA) was performed by applying fluorescence spectroscopic methods under simulated physiological conditions. The mechanism of fluorescence quenching of BSA by Cy was also studied. Parameters such as bathing temperature, time and solution pH were investigated to optimize the fluorescence quenching. The binding type, binding ratio and binding constant between BSA and Cy were calculated by using the Stem-Volmer equation. Experimental results indicated that Cy can quench the fluorescent emission of BSA statically by forming a 1∶1 type non-covalent complex and the binding constant is 5.6×103 L·mol-1. Synchronous fluorescence spectral research shows Cy may affect the fluorescence emission of Trp residues of BSA. Furthermore, molecular docking is utilized to model the complex and probe the plausible quenching mechanism. It can be noted that the hydrogen bindings and hydrophobic interactions between Cy and BSA change the micro-environment of Trp213, which leads to the fluorescence quenching of BSA.