钙调神经磷酸酶B亚基及钙调素的EPR研究

EPR STUDY ON CALCINEUR IN B SUBUNIT AND CALMODULIN

根据顺磁离子Mn^(2+)的取代特性,用EPR方法研究了钙调神经磷酸酶B亚基与其4个Ca^(2+)的结合位点,以及它们亲和力的细微差别。并同时进行了钙调素的对比研究。实验和Scatchard作图表明,B亚基有4个Ca^(2+)结合位点,2个高亲和力结合位点,其解离常数为4×10^(-6)mol/L;2个低亲和力结合位点,解离常数为9×10^(-5)mol/L。钙调素也有2个Ca^(2+)高亲和力结合位点,其解离常数为8×10^(-6)mol/L,2个低亲和力结合位点,解离常数为7×10^(-5)mol/L。钙调神经磷酸酶B亚基和钙调素Mn^(2+)结合位点的EPR研究对B亚基和钙调素在共同调节钙调神经磷酸酶中的作用提供了有用的信息。

Ca^(2+) binding sites to calcineurin B subunit (CaN B sub.) and calmodulin (CaM) have been studied with EPR techniques by using paramagnetic metal ion Mn2+ as substitutes for Ca2+.Experiment results and Scatchard Plots showed the stoichiometry and different affinity of Ca2+ sites of CaN B sub. and CaM. There are 4 Mn2+ binding sites in CaN B sub, two high affinity binding sites with KD 4 × 10^(-8) Mol/L and two low affinity binding sites with KD 9 × 10^(-5) Mol/L. In CaM there are 4 Mn2+ binding sites also, two high affinty binding sites with KD 8 × 10^(-6) Mol/L and two low affinity binding sites with KD 7 × 10^(-5) Mol/L.EPR study of Mn2+ binding CaN B sub. and CaM provided useful information for the mechanism of cooperative regulating CaM by CaN B sub. andCaM.