熊果酸与血清白蛋白的结合反应机制研究

Study on the Binding Interaction between Ursolic Acid and Serum Albumin

采用荧光光谱法研究牛血清白蛋白(BSA)和人血清白蛋白(HSA)与熊果酸(UA)分子之间的结合作用机制。基于荧光猝灭法测定反应的结合常数(K)分别为:KUA-BSA=0.335 7×105L/mol,KUA-HSA=0.244 3×105L/mol,依据F嵀rster非辐射能量转移机制确定授体-受体间的结合距离(r)及能量转移效率(E)分别为:rUA-BSA=0.73 nm,rUA-HSA=0.88 nm,EUA-BSA=0.17,EUA-HSA=0.18;通过同步荧光技术确认熊果酸结合血清白蛋白反应过程中对其构象的影响并不显著,应用荧光相图技术解析得出血清白蛋白与熊果酸结合反应中蛋白质折叠变化型态为"二态"模型。此外,探讨金属离子Ni(Ⅱ)存在下熊果酸与血清白蛋白的结合反应,得到相互作用机制具有一定差别的结论。

The interaction between ursolic acid（UA） and serum albumin,namely bovine serum albumin（BSA） and human serum albumin（HSA） respectively has been studied by fluorescence spectroscopy.Based on the method of florescence quenching,the binding constants（K） for UA with BSA/HSA were determined to be KUA-BSA=0.3357×10^5L/mol and KUA-HSA=0.2443×10^5L/mol,respectively.The binding distance（r）and energy-transfer efficiency（E）between UA and BSA/HSA were also obtained by virtue of the Fōrster theory of non-radiation energy transfer to be as follows： rUA-BSA=0.73nm,rUA-HSA=0.88nm,EUA-BSA=0.17,EUA-HSA=0.18.The effect of UA acting on the conformation of BSA/HSA analyzed by synchronous fluorescence spectroscopy was not significant.The unfolding procedure of BSA/HSA induced by UA was analyzed by fluorescence phase diagram to be a two-state model.In the presence of Ni（Ⅱ）,interaction between UA and BSA/HSA was explored to be somewhat different.