La(Ⅲ)与HSA或BSA的结合平衡研究

Binding Equilibrium Study Between La(Ⅲ) and HSA or BSA

用平衡透析法详细研究了 p H=6.3条件下 La( )与 HSA或 BSA的结合平衡 .Scatchard图分析表明 ,La( )在 HSA中有 2个强结合部位和 8个弱结合部位 ;在 BSA中有 2个强结合部位和 6个弱结合部位 .从 La( )与 Cu( ) ,Zn( )和 Cd( )等的竞争结合 HSA或 BSA的结果推测 :La( )在 HSA或 BSA中的一个强结合部位的配位原子可能全部是氧原子 .通过非线性最小二乘法拟合 Bjerrum方程 ,首次报道了La( ) -HSA和 La( ) -BSA体系的逐级稳定常数值 ,其 K1 的数量级为 1 0 4.Hill系数及自由能偶合分析表明 La( )与 HSA或 BSA的结合均产生一定的负协同效应 .

The binding of La(Ⅲ) to human serum albumin (HSA) or bovine serum albumin(BSA) has been studied by equilibrium dialysis at pH 6.3. The results from Scatchard plots indicate that there are two strong sites and eight weak sites in HSA and two strong sites and six weak sites in BSA, respectively. The results of La(Ⅲ)competing with Cu(Ⅱ), Zn(Ⅱ), Cd(Ⅱ) for binding to HSA or BSA suggest that one of the strong binding sites is most probably coordinated with atoms which are almost all oxygen. The successive stability constants which are reported for the first time are obtained by non linear least square method fitting Bjerrum formula. For both La(Ⅲ) HSA and La(Ⅲ) BSA systems, the order of magnitude of K 1 was found to be 10 4. The analyses of Hill coefficient and free energy coupling show that some negative cooperative effect was found in both La(Ⅲ) HSA and La(Ⅲ) BSA systems. [WT5HZ]