Zhang Hai-Rong, Bian He-Dong, Pan Ying-Ming, Tian Jian-Niao, Yu Qing, Liang Hong, Chen Zhen-Feng
Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, Ministry of Education, Guangxi Normal University, Guilin 541004, China.
Guang Pu Xue Yu Guang Pu Fen Xi. 2009 Nov;29(11):3052-6.
In the present work, the interaction of catechin with bovine serum albumin (BSA) under physiological condition was studied by fluorescence quenching spectra in combination with Fourier transform infrared (FTIR) spectroscopy. The binding constants, the drug-binding mode, the binding site between catechin and BSA in aqueous solution at pH 7.40, and the effect of common ions were studied. The results show that catechin has the ability to quench the intrinsic fluorescence of BSA because of a complex formed, and the quenching mechanism is static quenching. The binding constants K under 296, 303 and 310 K were 2.368, 2.249 and 2.152 x 10(6) L x mol(-1) respectively. The thermodynamic parameters showed that the interaction between catechin and BSA was driven mainly by hydrophobic force and electrostatic interaction. The displacement experiment shows that catechin can bind to the site I of BSA. The distance between the 214 tryptophan residues in BSA and catechin was estimated to be 1.46 nm using Foster's equation on the basis of fluorescence energy transfer. According to FTIR, the secondary structure of BSA changed when catechin was added.
在本研究中，采用荧光猝灭光谱结合傅里叶变换红外（FTIR）光谱法研究了儿茶素在生理条件下与牛血清白蛋白（BSA）的相互作用。研究了结合常数、药物结合模式、pH 7.40水溶液中儿茶素与BSA的结合位点以及常见离子的影响。结果表明，儿茶素由于形成复合物而具有猝灭BSA固有荧光的能力，猝灭机制为静态猝灭。296、303和310 K下的结合常数K分别为2.368、2.249和2.152×10(6) L×mol(-1)。热力学参数表明，儿茶素与BSA之间的相互作用主要由疏水作用力和静电相互作用驱动。置换实验表明，儿茶素可与BSA的位点I结合。基于荧光能量转移，利用Foster方程估计BSA中214位色氨酸残基与儿茶素之间的距离为1.46 nm。根据FTIR结果，添加儿茶素后BSA的二级结构发生了变化。
