铜离子对铜锌超氧化物歧化酶二聚作用的影响

The effect of copper ion on the dimerization of Cu,Zn superoxide dismutase

观测了Cu^2＋在脱辅基SOD（apoSOD）二聚过程中的作用．探讨了过氧化氢和pH值对SOD二聚体形成的影响，以及缺锌多铜SOD（Cu^2＋SOD）诱导其他蛋白质聚集的作用．结果显示Cu^2＋SOD自聚集成二聚体，在SDS作用下不解聚；pH值为5．6～6．8最有利于Cu^2＋SOD二聚体的形成．而过氧化氢的存在导致Cu^2＋SOD二聚体解聚成单体．另一方面，发现Cu^2＋SOD能够诱导结构类似的apoSOD，Zn4SOD和Cu2Zn2SOD形成不被SDS解聚的二聚体，而对其他蛋白质没有影响，表明Cu^2＋SOD诱导蛋白质聚集时有一定的空间结构选择性．

It has been proposed that the altered metal binding properties within the Cu, Zn superoxide dismutase （Cu2Zn2SOD）, and the resulting SOD dimer might be contributors to the toxic functional gain of the enzyme. Here, the roles of Cu^2＋ in the apoSOD dimerization, and the effect of H2O2 and pH on formation of the apoSOD dimer were examined. In addition, the co-aggregation of the Zn-deficient, Cu-containing SOD （Cu.SOD） with other proteins was also studied. The results show that the Cu.SOD spontaneously converts into a dimer, and pH5.6-6.8 facilitates this dimerization. The addition of H2O2 led to the conversion of the Cu.SOD dimer into a monomer. It was also found the Cu.SOD can produce a co-aggregation with the proteins apoSOD, Zn4SOD, and Cu2Zn2SOD, which have an overall structure similar to the Cu.SOD.