山奈素与牛血清蛋白相互作用:Tachiya模型与Stern-Volmer方程的对比研究

Study on the Interaction of Kaempferide with Bovine Serum Albumin: Comparison of Tachiya Model and Stern-Volmer Equation

在模拟人体生理条件下,利用荧光光谱、紫外吸收光谱研究了不同温度(298、304、310 K)时,山奈素(KF)与BSA之间的相互作用。分别使用Tachiya模型与Stern-Volmer方程探讨了KF-BSA之间的结合常数、结合位点数及结合距离。结果表明,使用Tachiya模型时,体系结合常数与结合距离均随温度的升高而增大,这种趋势与Stern-Volmer方程得到的结果变化趋势一致。由Stern-Volmer方程获得的结合位点数几乎不随着温度变化而变化,但由Tachiya模型得到的实际结合位点数则随温度的改变而变化很大。Tachiya模型得到的结果更符合小分子与生物大分子相互作用的实际情况。热力学数据表明KF与BSA之间主要依靠疏水作用力结合。并利用同步荧光光谱法研究了KF对BSA构象的影响。

Under the simulated physiological conditions （at pH 7.4 and ionic strength of O. 15 mol L-l） , the interaction between kaempferide （KF） and bovine serum albumin （BSA） was assessed via fluorescence spectroscopy and ultra-violet absorption spectra under different temperatures, such as 298, 304 and 310 K. The binding constant, number of binding sites and binding distance between KF and BSA were analyzed and contrasted by aid of the Taehiya model and Stern - Volmer e- quation, respectively. The result showed that, for Taehiya model, the binding constant and the binding distance increased with the increase of the temperature, the same as the change trend for Stern - Volmer equation. But the number of binding sites obtained by Tachiya model was much differ- ent from that by Stem - Volmer equation. The number of binding sites obtained by Stern - Volmer e- quation almost had no change with the temperature increasing; To the contrary, the number of bind- ing sites obtained by Tachiya model had a great change with the temperature increasing. The result obtained by Tachiya model corresponds more closely to the practical conditions of interaction between small molecular and biological molecules than that by the Stem - Volmer equation. The thermody- namic parameters were calculated according to the van＇t Hoff equation. The enthalpy change AH, and the entropy change AS were found to be 179. 87 kJ mol-1 , 705.61 J mol-1 . K-1, respec- tively. The thermodynamic results suggest that hydrophobic force plays a major role in stabilizing KF - BSA complex. The effect of KF on the conformation of BSA was also studied by synchronous flu- orescence spectra. It indicated that the binding of KF to BSA leads to changes in the conformation of BSA. The interaction between KF and BSA was realized through the combination of KF and trypto- phan residue.