EPR STUDY ON CALCINEUR IN B SUBUNIT AND CALMODULIN
钙调神经磷酸酶B亚基及钙调素的EPR研究

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.