大黄素铜锌配合物与牛血清白蛋白的相互作用研究

Study on the interaction between bovine serum albumin and emodin-Cu and emodin-Zn complex

采用荧光猝灭光谱、同步荧光和紫外光谱研究并比较大黄素及其铜、锌配合物与牛血清白蛋白(BSA)之间的相互作用。大黄素及其配合物均能显著猝灭BSA的内源荧光并以静态猝灭为主。在293K和300K时,大黄素及其铜、锌配合物与BSA结合常数分别为(L·mol^(-1)):4.57×10~4,1.76×10~4、1.28×10~5和2.72×10~4,0.980×104,2.34×10~4;根据热力学参数判断大黄素铜、锌配合物与BSA之间的作用力主要为范德华力和氢键;依据F9rster非辐射能量转移理论,计算出大黄素及其铜、锌配合物在蛋白质中的结合位置与色氨酸残基间的距离分别为为2.24、2.37和2.82 nm。结果还表明金属离子如铜、锌离子的存在会显著影响大黄酸与BSA的结合,同步荧光光谱研究表明大黄素铜、锌配合物都未能够使BSA构象发生变化。大黄素形成配合物后与BSA的结合发生较大变化,会对大黄素及金属离子的储运产生影响。

Fluorescence spectroscopy, synchro-fluorescence spectra and absorption spectra were utilized to study and compare the in-teraction between bovine serum albumin（ BSA） and emodin（EM）or its copper and zinc complexes. Emodin and its complexes could significantly quench the endogenous fluorescence of BSA mainly by a static mode. The binding constants Kh of E M , E M - C u , a n d E M - Zn with BSA are（L ·mol^-1）4. 57×10^ 4 ,l. 76×10^ 4,1. 28×10^ 5 at293K a n d 2. 72×10^ 4 ,0. 9 8 0×10^ 4 ,2. 3 4 ×10^ 4 at 3 0 0 K , respectively. Judged from the thermodynamics parameter,we can learn that the major forces between emodin or its complexes and the BSA are vander walls force and hydrogen bond. Based on Forster non-radiation energy transfer mechanism,the binding site were found to be 2. 24,2. 37. and 2. 82 nm away from tryptophan residue in BSA for EM,EM-Cu and EM-Zn,respectively. The results also show thatthe binding constant of EM with BSA can be significantly affected by co-existence of Cu2＋ ,Zn2＋. The binding ability of EM with BSA cannot significantly change after forming metal complexes and then affect the Storage and transportation of EM and metal ions.