Cu,Zn-SOD酶模型配合物催化O_2^-歧化作用的研究

STUDY OF THE CATALYTIC ACTIVITY OF THE MODEL COMPLEXES OF Cu,Zn-SOD IN O2- DISPROPORTIONATION

为了解Cu,Zn-SOD酶中Cu周围环境对催化O_2^-歧化作用活性的影响,本文用NBT法测定了Cu,Zn-SOD酶及一系列咪唑桥异核模型配合物催化O_2^-歧化作用的活性,并用ESR方法鉴测了其中一个配合物与O_2^-作用的中间过程。结果表明,具有平面四方构型或轴向有弱配位H_2O或ClO_4^-基团的四方锥构型的Cu^(2+)配合物具有较高活性,说明配合物催化歧化O_2^-过程中,Cu^(2+)可能首先以轴向与O_2^-配位,形成Cu^(2+)-O_2^-中间化合物,紧接着Cu^(2+)被还原成Cu^+。

In order to elucidate the relationship between the structure of active site and the activity of Cu,Zn-SOD, the catalytic activity of the model complexes of Cu,Zn-SOD in disproportionation of O2 was determined by NBT method at pH = 8.8. The results indicate the complexes with Cu in N4 or N2O2 planar square of square pyramid with weak bonding H2O or C1O4 in the axial position have higher activity of O2 disproportionation. This is possibly because in the catalytic process O2 attaches itself to the Cu atom from the axial direction or replaces the weakly bound H2O or C1O4 in the axial position with the formation of a Cu-O2 intermediate complex.