光谱法研究氨基己酸与牛血清白蛋白的相互作用

Spectroscopic Studies on the Interaction between Amidocaproic Acid and Bovine Serum Albumin

利用荧光光谱、紫外-可见吸收光谱及圆二色(CD)光谱研究了模拟生理条件下的氨基己酸(ACA)与牛血清白蛋白(BSA)的相互作用。实验结果分析表明,氨基己酸对BSA的内源性荧光具有猝灭作用,属于动态猝灭过程。计算了2种温度下ACA-BSA体系的结合常数、结合位点数及反应的热力学参数ΔG、ΔH和ΔS分别约为-21.00kJ/mol、-0.64kJ/mol和-72.00kJ/(mol·K),由此推出了二者主要通过氢键和范德华力形成摩尔比为1:1的复合物。依据Frster非辐射能量转移理论求得二者之间的结合距离为2.3nm。位点取代实验指出氨基己酸主要结合在位点SiteI。CD光谱表明,氨基己酸诱导了BSA分子二级结构微变。

The interaction between amidocaproic acid （ACA） and bovine serum albumin （BSA） was investigated by spectroscopic techniques including fluorescence,UV visible absorption and circular dichroism （CD） spectroscopies under simulative physiological conditions.The fluorescence quenching mechanism of BSA by ACA could be attributed to a dynamic quenching according to the Stern-Volmer equation and UV absorption spectra of BSA.Hydrogen bondings and van der Waals interactions are responsible for their interaction on the basis of the calculated thermodynamic parameters,binding constants and binding site numbers.A 2.3 nm binding distance between ACA and BSA was obtained based on the theory of Frster＇s non-radiation energy transfer.From displacement experiments it was identified that ACA binds to protein BSA at site I.Moreover,CD spectra demonstrated that the second structure of BSA induced a slight structural change after binding ACA.