含磷三足体稀土铕(Ⅲ)配合物与牛血清白蛋白的作用机理

Mechanism of the Interaction Between a Phosphorus-containing Tripod Ligand Europium( Ⅲ) Complex and Bovine Serum Albumin

在p H=7.3的Tris-HCl缓冲溶液(模拟生理条件)中,采用荧光光谱、循环伏安曲线和紫外光谱研究了N-二(苯-二氨基甲酰基)甲基磷酸铕(Ⅲ)配合物[Eu(pic)3L]与牛血清白蛋白(BSA)的相互作用.实验结果表明:配合物与BSA可以形成1∶1结合型无荧光复合物Eu(pic)3L-BSA,Eu(pic)3L对BSA内源荧光的猝灭类型为静态猝灭.根据双对数回归方程计算出二者在不同温度下的结合常数K及结合位点数n,通过热力学参数得出配合物与BSA之间以氢键和范德华力为主.根据Foster的偶极-偶极无辐射能量转移机理可知配合物与BSA之间可能以偶极-偶极无辐射能量转移方式进行能量传递.分别考察了Fe3+和Cu2+对配合物与BSA结合作用的影响,推测Fe3+和Cu2+可能在配合物与BSA间起"离子架桥"作用,使Eu(pic)3L-BSA复合物的稳定性增强.循环伏安法研究结果表明配合物与BSA相互作用形成无电活性的Eu(pic)3L-BSA复合物,使得溶液中游离的配合物浓度降低.

Under the simulated physiological condition （Tris-HC1 buffer, pH = 7.3 ）, the interaction of N-bis （benzene-diamino formyl）methyl phosphate europium（ Ⅲ ） complex[ Eu （pic）3L] and bovine serum albumin （BSA） was studied by fluorescence spectrometry, cyclic vohammetry and UV spectroscopy. The results indicate that no fluorescent compound[ Eu （pie）3L-BSA （ratio 1 ： 1 ） is formed and the complex can markedly quench the intrinsic fluorescence of BSA via a static quenching process. The binding constant（K） and binding site number（n） were calculated according to the double logarithm regression equation under different temperatures, the thermodynamic parameters show that the main force between complex and BSA is hydrogen bonding and van der Waals forces. The complex and BSA may have dipole-dipole non-radiation energy transfer according to the Foster＇ s theory of dipole-dipole non-radiation energy transfer. The effects of metal ions Fe3＋ and Cu2＋on the interactions between BSA and complex were investigated, and the results show that Fe3＋and Cu2＋ may play ＂ion bridge＂ role in complex and BSA, making the stability of Eu（ pic）3L-BSA enhanced. Cyclic voltammetry results indicate that non-electri（c activity compound Eu （pic）3 L-BSA is formed, which lower the free complex concentration in the solution.