共振光散射法研究硫酸粘杆菌素与牛血清白蛋白间的反应机理

在pH 7.40缓冲溶液条件下，以牛血清白蛋白(BSA)为检测对象，利用共振光散射法分别研究了298，310，318 K三个温度下BSA和硫酸粘杆菌素(CS)之间的相互作用机理。结果证明：该体系在反应过程中，主要的猝灭方式为生成新物质的静态猝灭;n值约为1，表明CS与BSA发生作用时只有一个结合位点;由热力学参数得知该体系的反应过程是自发进行的，药物与蛋白质主要是通过静电力结合;Hill系数约等于1，表现为零协同作用。将所得实验数据与荧光猝灭法所得数据进行比较，比较显示：利用共振光散射法所计算的猝灭参数(K_sv，K_q，n，K_a)与荧光猝灭法所得猝灭参数数值相似，猝灭结论一致，验证了该方法的正确性，说明共振光散射法用于研究蛋白质与药物的相互作用是可行的。共振光散射法与检测物质本身有无内源荧光无关，因此也可以用于没有内源荧光物质的研究，这使小分子与蛋白质相互作用的研究方法得到拓宽。

The Investigation on the Interaction of Colistin Sulfate with Bovine Serum Albumin with Resonance Light Scattering Spectroscopy

The interaction between colistin sulfate (CS)with bovine serum albumin in physiological buffer (pH 7.4)was investi-gated with resonance light scattering spectroscopy at 298,310,and 318 K.The analysis of data indicated that quenching mecha-nism of BSA-CS was probably static.The value of n was approximately 1 ,indicating there was only a single class of binding sites on BSA for CS compounds.The thermodynamic parameters were calculated at different temperatures,implying that the interac-tion was spontaneous and electrostatic force played major role in the binding between CS and BSA.The values of nH were equal to 1 at different temperatures,indicating there was non-cooperative reaction between BSA and CS.The feasibility of resonance light scattering spectroscopy was verified by fluorescence quenching spectroscopy.The quenching reactive parameters (KSV ,Kq , n,Ka )from two methods were similar,suggesting resonance light scattering spectroscopy could be used to study the binding in-teraction between protein and drugs.Resonance light scattering spectroscopy can be used to explore the substance without intrin-sic fluorescence,suggesting that the application of resonance light scattering spectroscopy broadens the understanding of the in-teraction between small molecules and protein.