荧光光谱法研究锆离子存在下槲皮素及人血清白蛋白的相互作用

Interactions between quercetin and human serum albumin in presence of zirconium ion by fluorescence spectrometry

目的采用荧光光谱法研究有无锆离子(Zr4+)共存时槲皮素与人血清白蛋白(HSA)的相互作用。方法于10 mL的比色管中,依次加入0.20 mol/LTris-HCl缓冲溶液(pH 7.40)2.50 mL,0.10 mol/L NaCl溶液1.0 mL,一定量的HSA溶液,Zr4+溶液,槲皮素溶液,用二次蒸馏水定容至10 mL。HSA荧光激发/发射波长为281/352 nm,激发和发射光狭缝宽度为3 nm,在波长300～500 nm内记录荧光光谱。结果测得了有无锆离子存在时槲皮素-HSA结合反应的平衡常数和结合摩尔位点数分别为1.032×106L/mol、2.964×105L/mol,1.13、1.07;确定槲皮素-HSA的作用类型为静态猝灭过程。结论锆离子、槲皮素对HSA荧光均有猝灭作用,而且二者共存时对HSA荧光有协同猝灭作用,其猝灭机制为槲皮素与锆离子形成配合物后再对HSA的荧光有猝灭作用,而不是槲皮素和锆离子各自猝灭的简单累加。

Objective To study the interactions between quercetin（Qct） and human serum albumin（HSA） with or without zirconium ion（Zr4＋） coexisting by fluorescence spectrometry.Methods A series of solutions,0.20 mol/L Tris-HCl buffer solution（pH 7.40） 2.50 mL,0.10 mol/L NaCl solution 1.0 mL,a certain amount of HSA stock solution,Zr4＋ solution,Qct solution,and ddH2O were successively added into a 10 mL colorimetric tubes.The fluorescence excitation/emission wavelengths of HSA was 281/352 nm,the slit width of excitation/emission was 3 nm,and the fluorescence spectrometry of the solution was scanned from 300 to 500 nm.Results For Qct-Zr4＋-HSA and Qct-HSA,the effective quenching constants（Ka） and binding molar site number were 1.032 × 106 L/mol and 2.964 × 105 L/mol,1.13 and 1.07,respectively.The interaction between Qct and HSA was static quenching process.Conclusion The results show that both Zr4＋ and Qct have quenching effects on HSA,and coexisting of the both has the synergic quenching effects on HSA.The study on the quenching mechanism reveals that the quenching effects of Qct-Zr4＋ on HSA is due to the complex of Qct and Zr4＋rather than the simple accumulation of respective quenching of Qct and Zr4＋.