大黄酸及大黄素和牛血清白蛋白的相互作用

Interaction of Rhein and Emodin with Bovine Serum Albumin

采用荧光猝灭和红外光谱方法考察了两种大黄蒽醌类化合物(大黄酸和大黄素)与模型蛋白牛血清白蛋白之间的相互作用。结果表明,大黄酸和大黄素主要通过静电作用与牛血清白蛋白形成基态化合物,从而使其内部荧光猝灭,并获得了二者相互作用的结合常数、结合位点数及大黄酸和大黄素与色氨酸结合的空间距离。金属离子对这两种大黄蒽醌类化合物与牛血清白蛋白的结合具有一定的影响。红外光谱显示大黄酸和大黄素均可引起牛血清白蛋白二级结构的变化。通过比较大黄酸、大黄素和其他几种大黄蒽醌类化合物发现酚羟基的个数以及C(3)位取代基的极性对于化合物的活性具有重要意义。

The interaction between two anthraquinones（rhein and emodin） and model protein（bovine serum albumin） was investigated by fluorescence quenching technique and infrared spectroscopy.The results showed that rhein and emodin mainly formed ground-state complex with bovine serum albumin by electrostatic interaction,which led to the quenching of intrinsic fluorescence of bovine serum albumin.The binding constant,number of binding site and the distance between rhein,emodin and tryptophan residue were determined.Some metal ions had effect on the binding of these two anthraquinones and bovine serum albumin.The infrared spectra showed that both rhein and emodin induced secondary structure change of bovine serum albumin.The interaction was also compared with other three anthraquinones,which indicated that the number of phenolic hydroxyl group and the polarity of the substituent group on C（3） had a significant effect on the activity of the compounds.