金(Ⅲ)与血清白蛋白的结合及其后续效应研究

Binding Equilibrium Study between Au(Ⅲ) and Serum Albumin

在生理pH(7.43±0.02)条件下,用平衡透析法和紫外光谱、荧光光谱研究了金(Ⅲ)与人血清白蛋白(human serum albumin,简称HSA)或牛血清白蛋白(bovine serum albumin,简称BSA)的结合.Scatchard图分析表明,金(Ⅲ)在HSA或BSA中有强弱两类结合部位,通过计算机拟合获得结合的逐级稳定常数值.利用荧光猝灭法计算出金(Ⅲ)-HSA和金(Ⅲ)-BSA体系的Sterm-Volmer常数和双分子猝灭速率常数.紫外扫描发现金(Ⅲ)与HSA或BSA的结合存在可能诱导蛋白质构象发生缓慢变化(A^B),测得并讨论了这一构象变化的速度常数和活化参数.我们认为金(Ⅲ)能与血清白蛋白中的硫、氧、氮等结合形成平面四方型的配合物.

This paper has minutely studied the interaction between Au（Ⅲ） and serum albumin. The binding of between An（Ⅲ） to human serum albumin（HSA） or bovine serum albumin（BSA） has been studied by equilibrium dialysis at pH （7.43 ± 0.02）. The Scatchard analysis indicates that there exists several strong binding sites of Au（ Ⅲ ） in both HSA or BSA. A notable hysteretic effect has been observed in the interaction of Au（ Ⅲ ） and serum albumin using UV-visible spectrometry at pH（（7.43 ±0.02）, which shows that the binding between Au（ Ⅲ ） and serum albumin might induce a slow transition of HSA or BSA from the conformation of weaker affinity for Au（ Ⅲ ） to one of stronger affinity （A-B transi- tion）. The rate constants and activation parameters of these transition parameters of this transition were measured and discussed. The binding equilibrium has been also studied by fluorescence quenching.