光谱法研究7-[(8-喹啉)偶氮]-8-羟基喹啉-5-磺酸与蛋白质相互作用

The interaction between 8-hydroxy-7-(quinolin-8-ylazo)- quinoline-5-sulfonic acid and protein by spectroscopy

应用紫外吸收光谱法和荧光光谱法研究了7-[（8-喹啉）偶氮]-8-羟基喹啉-5-磺酸（简称主体）与蛋白质的相互作用.在p H=7.40的Tris-HCl缓冲溶液中,主体分子在400 nm处发射弱荧光,其荧光强度随白蛋白的加入明显增强.据此建立测定微量蛋白质的新方法.在相同的实验条件下,测定牛血清白蛋白和人血清白蛋白,线性范围分别为1.0×10^-6~2.7×10^-5mol/L和2.5×10^-7~9.5×10^-6mol/L,检测限分别为8.09×10^-7mol/L、1.05×10^-7mol/L.同时讨论7-[（8-喹啉）偶氮]-8-羟基喹啉-5-磺酸对白蛋白内源荧光的猝灭机理,测定牛血清白蛋白和人血清白蛋白结合常数分别为3.38×10^5和7.28×10^6,结合位点数分别为1.218和1.412.依据Forster非辐射能量转移理论,确定了主体-受体间的结合距离rBSA=3.98 nm,rHSA=3.04 nm及能量转移效率EBSA=0.038,EHSA=0.161,用同步荧光技术考察主体对蛋白质构象的影响。

The binding characteristics of 8-hydroxy-7-（quinolin-8-ylazo）-quinoline-5-sulfonic acid （host） and serum albumin were studied by fluorescence and absorption spectroscopy in aqueous solution.The host gave fluorescence emission at 400 nm （Aox=320 nm）in a Tris-HC1 buffer solution （pH=7.40）. A new method for the determination of trace protein HSA has been developed based on the enhanced fluorescence emission in the presence of a certain amount of protein. Under the same conditions the liner range concentration was at 1.0×10^-6-2.7×10^-5 mol/L and 2.5×10^-7-9.5×10^-6 mol/L, for bovine serum albumin and human serum albumin, respectively. The detection limit was 8.09×10×-7 mol/L, 1.05×10^-7 mol/L.At the same time, the results show that the binding constants, the number of binding sites and the quenching mechanism of fluorescence of serum albumin by host indicate a static quenching procedure for bovine serum albumin and human serum albumin.The binding constants is 3.38 × 10^5 and 7.28 × 10^6, the number of binding sites is 1.218 and 1.412. The binding distance between host （rBSA=3.98 nm, rHSA=3.04 nm） and serum albumin and the energy transfer efficiency （EBSA=0.038, EHSA=0.161） are obtained based on the theory of Forester spectroscopy energy transfer. The effect of host on the conformation of serum albumin is further analyzed by synchronous fluorescence spectrometry.