吲哚美辛与牛血清白蛋白相互作用的光谱研究

Spectroscopic studies on the interaction of indomethacin with bovine serum albumin

在模拟生理条件下,用荧光光谱法结合圆二色谱法研究了吲哚美辛(IM)与牛血清白蛋白(BSA)的相互作用。实验结果表明,IM对BSA的猝灭机制属于形成复合物的静态猝灭过程,由修正的Stern-Volmer方程求出不同温度下相应的结合常数分别为11.87×104、8.351×104、6.110×104 L.mol-1。利用范特霍夫方程及结合常数的数据分别计算体系的焓变、熵变和吉布斯自由能变。焓变值(-42.54 kJ.mol-1)和熵变值(-45.65J.mol-1.K-1)表明,氢键和van der Waals是IM与BSA之间缔合作用的主要作用力。圆二色谱、三维荧光光谱的研究结果显示,在与IM结合后,BSA中α-螺旋的含量减少,说明在与IM结合反应过程中,BSA的微环境和构型发生了改变。

The interaction between indomethacin（IM）and bovine serum albumin（BSA）was investigated by fluorescence spectroscopy combined with circular dichroism spectroscopy under simulative physiological conditions.The experiment results showed that the fluorescence intensity of BSA was dramatically decreased owing to the formation of IM-BSA complex.The corresponding effective quenching constants（Ka）between IM and BSA at three different temperatures（298,304 and 310 K）were 11.87×104,8.351×104 and 6.110×104 L·mol-1,respectively.The thermodynamics parameters：enthalpy change（ΔH）and entropy change（ΔS）were calculated to be-42.54 kJ·mol-1 and-45.65 J·mol-1· K-1,which suggested that hydrogen bond,van der Waals force interaction was the predominant intermolecular force in stabilizing the complex.The conformational investigation showed that the presence of IM decreased the α-helical content of BSA and induced the slight unfolding of the polypeptides of protein,which confirmed some micro-environmental and conformational changes of BSA molecules.