荧光猝灭法研究Mn(Ⅱ)和Zn(Ⅱ)与牛血清白蛋白的结合竞争

Study on Binding Competition Between Mn(Ⅱ) and Zn(Ⅱ) to Bovine Serum Albumin by Fluorescence Quenching Method

应用荧光光谱法研究了Mn(Ⅱ)与牛血清白蛋白(BSA)间的结合作用;采用荧光猝灭法计算出不同温度下Mn(Ⅱ)与BSA结合的结合常数、结合位点数、热力学参数;采用同步荧光技术考察了Mn(Ⅱ)对BSA构象的影响,并讨论了Mn(Ⅱ)与BSA的结合模式。结果表明,Mn(Ⅱ)与BSA的结合位点数为1,猝灭过程为动态猝灭,结合过程主要是熵驱动,相互作用力主要为疏水作用力。在此基础上采用荧光猝灭法进一步研究了Mn(Ⅱ)-BSA-Zn(Ⅱ)双金属体系中Mn(Ⅱ)、Zn(Ⅱ)与BSA的相互作用;在Stern-Volmer方程的基础上推导出双金属体系中荧光猝灭的缔合公式;在与单金属体系对比后,推测出Zn(Ⅱ)会竞争Mn(Ⅱ)与BSA的结合。

The binding between MN（ Ⅱ ） and bovine serum albumin（BSA） was investigated by fluorescence spectrum. The binding constant, the number of binding site and thermodynamic parameters were measured at different temperatures by fluorescence quenching method. The effect of Mn（ Ⅱ ） on the conformation of BSA had also been analyzed using synchronous fluorescence spectroscopy and the binding mode between Mn（ Ⅱ ） and BSA was discussed. Experimental results showed that the number of binding site was 1,the quenching process was dynamic quenching, the binding process was mainly entropy-driven and the interaction was mainly hydro- phobic force. On this basis,the binding between Mn （ Ⅱ ） ,Zn （ Ⅱ ） to BSA in Mn（ Ⅱ ）-BSA-Zn（ Ⅱ ） bimetallic system was investigated by fluorescence quenching method. The fluorescence quenching association formula for the bimetallic system was derived on the basis of the Stern-Volmer equation. By contrasted with the single met- al system,it was suggested that Zn（ Ⅱ ） competed with Mn（ Ⅱ ） for binding BSA.