锌离子的血清蛋白质输运机制研究

Exploration of the transport mechanisms of zinc ion binding with serum protein

采用等温滴定量热法研究血清白蛋白输运锌离子的相互作用机制,测定反应体系的结合参数与热力学参数,并讨论结合反应的分子作用机理。结果表明,血清白蛋白输运锌离子过程中,锌离子与血清白蛋白的结合反应符合langmuir模型,拥有强、弱两类结合位点。强结合位点的结合常数K1=1.86×105L.mol-1,结合位点数N1=1.17;弱结合位点的结合常数K2=7.16×103L.mol-1,结合位点数N2=2.85。分析血清白蛋白输运锌离子的热力学参数表明,两类结合过程均为自发过程,两类结合过程的主要作用力为静电作用力,且均表现为以焓驱动为主的焓熵协同驱动过程。

The interaction between zinc ion and bovine serum albumin（BSA） was investigated by using nano-watt-scale isothermal titration calorimetry, and the transport mechanisms of Zn2＋ binding with BSA was explored comparatively. The results show that the binding model about the interaction between zinc ion and bovine serum albumin conforms to the Langmuir model through the experi- mental data fitting. There are two types of binding sites between BSA and zinc ion;one is high-affinity binding,and the other is low- affinity binding. The number of high-affinity binding site（ N1 ）is 1.17 ,the binding constant（KI ）is 1.86×10^5L·mol^-1. The number of low-affinity binding site（ N2 ） is 2. 85, the binding constant（ K2 ） is 7.16 ×10^3L·mol^-1. The analysis of the thermodynamic param- eters of serum albumin transport zinc ion show that both types of binding are spontaneous. The two classes of binding process are driven by favorable entropy increasing with a less favorable enthalpy decroase;the main driving forces are the electrostatic interac- tion.