荧光猝灭法对肉桂酸与人血清白蛋白间的相互作用的研究

白蛋白是血液循环系统中最丰富的一种蛋白质,能与许多物质结合,并起着运输蛋白的作用。文章利用荧光光谱法研究了中药有效成分肉桂酸与人血清蛋白间的非共价结合特性。研究表明,在pH7.4作用液、286nm激发波长条件下,肉桂酸对人血清白蛋白的荧光发射有较强猝灭作用。当作用温度为37和47℃时,肉桂酸与人血清蛋白间的结合常数K分别为1.2767×103和3.4041×103L.mol-1,结合位点数n分别为0.7586和0.8356,表明温度升高有利于两者的结合;同时,根据不同作用温度时非共价结合复合物的热力学参数变化,证明肉桂酸与人血清白蛋白分子间的结合力主要是疏水作用。研究结果为进一步研究肉桂酸的药理作用,尤其是对血浆蛋白构像的影响提供了重要信息。

Study on the Interaction between Cinnamic Acid and Human Serum Albumin by Fluorescence Quenching Method

The albumin is the richest protein in blood circulatory system, which can combine with many drugs and play an important role in transporing protein. In the present work, the non-covalent interaction between human serum albumin and cinnamic acid was studied by using fluorescence quenching method. The results showed that cinnamic acid had a powerful ability to quench the fluorescence of human serum albumin at excitation and emission wavelengths of lambda(ex) = 286 nm and lambda(ex) = 340 nm, respectively, in the reaction solution of pH 7.4. The binding constants(K) at 37 and 47 degrees C were found to be 1.276 7 x 10(3) and 3.404 1 x 10(3) L x mol(-1), with the number of binding site(n) of 0.758 6 and 0.835 6, respectively, suggesting that the reaction temperature is advantageous for the binding reaction in a way. The changes in the thermodynamic parameters of binding interaction at 37 and 47 degrees C indicated that the main binding force between cinnamic acid and human serum albumin was hydrophobic force. These provide important information for studying the pharmacological effects of cinnamic acid and the influence of cinnamic acid on the configuration change of HSA.