Yan ShuLian, Liu YongLi, Tian XiaoJuan, Zhang YingXia, Zhou HaiMeng
Department of Chemistry, Capital University of Medical Science, Beijing, P.R. China.
J Protein Chem. 2003 May;22(4):371-5. doi: 10.1023/a:1025394224669.
The effect of extraneous zinc on calf intestinal alkaline phosphatase was studied for quick reversible binding and slow irreversible binding of zinc ions at various concentrations. Under the conditions of slow binding of zinc to CIP increasing Zn2+ (less than 1.0 mM, nM/nE 1.0 x 10(6)) inhibited enzymatic activity, and further increasing Zn2+ resulted in an increase of activity. For quick reversible binding of Zn2+, the effect on CIP activity changed at lower concentrations of substrate, indicating a complex cooperativity between Zn2+ and pNPP. Both protein intrinsic emission fluorescence and ANS-bound protein fluorescence, as well as circular dichroism spectra have shown that the binding of zinc ions changed the enzyme conformation, which was the reason for the changes in enzyme activity induced by extraneous zinc.
研究了外源锌对小牛肠碱性磷酸酶的影响，考察了不同浓度锌离子的快速可逆结合和缓慢不可逆结合情况。在锌与小牛肠碱性磷酸酶缓慢结合的条件下，增加Zn2+（小于1.0 mM，nM/nE 1.0×10(6)）会抑制酶活性，而进一步增加Zn2+则导致活性增加。对于Zn2+的快速可逆结合，在较低底物浓度下对小牛肠碱性磷酸酶活性的影响发生变化，表明Zn2+与对硝基苯磷酸酯之间存在复杂的协同作用。蛋白质固有发射荧光、ANS结合蛋白荧光以及圆二色光谱均表明，锌离子的结合改变了酶的构象，这是外源锌诱导酶活性变化的原因。
