The interaction between baicalin and human serum albumin (HSA) was investigated by fluorescence spectroscopy, circular dichroism, UV absorption spectroscopy, Fourier transform infrared spectroscopy and molecular modeling under simulated physiological conditions. The results indicated that the binding constants at 299 K and 309 K were calculated to be 1.28 × 105 L · mol-1 and 0. 91 × 105 L · mol-1, respectively. The thermodynamic parameters(the enthalpy change (△H): -26. 2 kJ · mol-1; the entropy change(△S): 10. 1 J · mol-1 · K-1) suggested that electrostatic interaction was the predominant force in the baicalin - HSA complex, though there was hydrophobic interaction. Molecular modeling suggested that baicalin was located in subdomain li A by hydrophobic and electrostatic forces, which agreed with the results obtained by fluorescence spectroscopy. The formation of the baicalin - HSA complex did not change the secondary structure of HSA by circular dichroism and Fourier transform infrared spectroscopy. Synchronous fluorescence showed that baicalin binding to HSA had changed the microenvironment around tryptophan(Trp) with polarity increasing.%利用紫外光谱、荧光光谱、傅立叶红外谱、圆二色谱及分子模型等技术,在生理pH条件下,研究了黄芩苷与人血清白蛋白(HSA)的相互作用,并计算了其结合常数和热力学参数.分子模型研究表明,黄芩苷与HSA在亚结构域ⅡA结合,二者间的作用主要为静电作用和疏水作用,与荧光光谱结果基本一致.红外光谱和圆二色谱显示黄芩苷与HSA结合后未改变HSA的二级结构.同步荧光光谱表明黄芩苷与HSA作用后使色氨酸残基所处的环境极性增加.
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