3,3',4',7-四羟基黄酮醇与人血清白蛋白结合的光谱学表征

应用荧光光谱和紫外光谱对3,3’,4’,7-四羟基黄酮醇(FIS)与人血清白蛋白(HSA)的结合机理进行了表征。在生理pH7.4下,FIS对HSA的内源荧光有显著的猝灭现象,在实验浓度范围内(药物与蛋白质浓度比0.1至10之间)其荧光猝灭机理主要是静态猝灭。研究结果表明,FIS和HSA之间形成了1∶1的复合物,结合常数为(1.05±0.18)×105L·mol-1。利用紫外光谱研究了FIS在不同pH值条件下的解离行为,发现FIS在生理条件下以离子和中性分子的混合形式存在。与蛋白质的结合使FIS的紫外吸收光谱Ⅰ带发生了明显的红移(与中性分子相比红移幅度超过40nm),证明了药物分子离子状态以静电力与蛋白质发生结合。其紫外光谱的二阶导数谱显示,药物分子与蛋白质的结合可分为特征和非特征形式。由于激发态质子转移,与蛋白质的相互作用引起了FIS内源荧光发射峰强度的明显增加,进一步证实了它们与蛋白质的结合。

Spectroscopic Characterization of Binding between Human Serum Albumin and 3,3',4',7-Tetradroxyflavone

The binding mechanism of human serum albumin with 3,3', 4', 7-tetradroxyflavone (FIS) was characterized by fluorescence and UV absorption spectra. The intrinsic fluorescence of HSA was significantly quenched by FIS in the physiological condition (pH 7.4), and the quenching mechanism is mainly static quenching process in the drug to protein molar ratio ranging from 0.1 to 10. The results revealed that the drug and protein formed 1 : 1 complex with the binding constants of (1.05 +/- 0.18) x 10(5) L x mol(-1). The dissociation behaviors of FIS in different pH conditions were investigated by UV absorption spectra, and it was found that FIS existed in the mixtures of ionic and neutral species. The UV absorption band I of FIS has a significant red shift (above 40 nm) after combination with HSA, demonstrating that FIS was bound to protein in ionic species which was driven by electrostatic force. The second derivative spectra of FIS showed that the combination included specific and non-specific forms. The intrinsic fluorescence of FIS was conspicuously enhanced in the presence of HSA due to the excited-state proton transfer (ESPT) and this further confirmed the complex formation of HSA with FIS.