Pb~(2+)与人血清白蛋白的相互作用

用平衡透析和差示吸收光谱法详细研究了Pb2+与人血清白蛋白(HSA)的相互作用.平衡透析研究结果表明,Pb2+与HSA的相互作用明显受到缓冲溶液pH影响,在pH 6.3和pH 5.4时,Pb2+在HSA上的强结合位点数分别是2.1个和1.1个,弱结合位点数分别为7.0个和2.4个,通过非线性最小二乘法拟合Bjerrum方程,首次报道了Pb2+-HSA体系的逐级稳定常数,Hill系数表明Pb2+与HSA的结合具有负协同效应.使用差示吸收光谱法研究物质的量比为1∶1的Pb2+-HSA体系的电荷转移谱带,发现组氨酸咪唑基是Pb2+在白蛋白中的优先配位基团.进一步根据Zn2+与Pb2+竞争结合HSA上的强结合位点,推断Pb2+在HSA中优先结合位点是位点A.

Interaction Between Pb2+Ions and Human Serum Albumin

The binding of Pb2+ to human serum albumin(HSA) has been studied by equilibrium dialysis.The results showed that the interaction between Pb2+ions and HSA was significantly influenced by pH of buffer solution.There existed 2.1 and 1.1 strong bindings site within HSA at pH 6.3 and pH 5.4,respectively.The successive stability constants which are reported for the first time are obtained by non linear least square method fitting Bjerrum formula.For Pb2+-HSA systems,the analyses of Hill plot indicate that there exists weak negative cooperative effect in Pb2+-HSA systems.The charge transition absorption bands of 1∶1 Pb2+-HSA system was further studied with differential absorption spectrum.The results indicated that histidine imidazole nitrogen was the preferential binding groups of Pb2+ions in HSA.The results of Pb2+ions competing with Zn2+ions to bind to the strong binding site in HSA suggested that the primary binding site for Pb2+ions was site A in albumin.