荧光光谱法研究偶氮胂Ⅲ与牛血清白蛋白的相互作用

Study on the Interaction of Arsenazo Ⅲ with Bovine Serum Albumin by Fluorescence Spectrum Method

目的为了研究偶氮胂Ⅲ与牛血清白蛋白(BSA)在不同pH条件下(pH=2.0～9.0)的相互作用机理。方法采用荧光光谱法研究偶氮胂Ⅲ对BSA荧光的影响,通过计算获得作用机理的诸多信息。结果偶氮胂Ⅲ对BSA有较强的荧光猝灭作用,猝灭机制为生成复合物的静态猝灭;偶氮胂Ⅲ与BSA间的结合常数在pH 3.0～5.0最大,结合位点数为1;pH=3.5和4.5时偶氮胂Ⅲ与BSA色氨基酸残基间的结合距离在4.10 nm左右;两者主要靠静电引力结合;金属离子Mg2+、Ba2+和Ca2+对两者结合作用有影响。结论偶氮胂Ⅲ及偶氮胂Ⅲ-Ba2+、偶氮胂Ⅲ-Ca2+可作为优良的光谱探针,用于蛋白质的定量测定。

Objective To investigate the interaction mechanism of arsenazo Ⅲ with bovine serum albumin （BSA） in Britton - Robinson buffer （ pH = 2.0 N 9.0）. Methods The fluorescence spectrum of BSA under the influence of arsenazo Ⅲ were determined by fluorescence spectrum method. And many parameters of the interaction mechanism were calculated. Results Arsenazo Ⅲ can strongly quench the fluorescence of BSA, and the quenching mechanism is static quenching with forming the complex. The binding constants reache maximum value at pH 3.0 - 5.0, the number of binding sites are about 1. The binding distances are about 4. 10 nm. The interaction between arsenazo Ⅲ and BSA is driven mainly by electrostatic forces. The binding constants change in presence of Mg^2＋ , Ba^2＋ and Ca^2＋. Conclusions Arsenazo Ⅲ , Arsenazo Ⅲ - Ba2＋ and Arsenazo Ⅲ - Ca^2＋ are good spectral probe for determination of proteins.