过氧化氢对铜锌超氧化物歧化酶活性及某些理化性质的影响

用H_2O_2作用于牦牛红细胞铜锌超氧化物歧化酶。观察到酶活性随H_2O_2浓度升高及作用时间增加而下降;酶分子连接的铜和锌有所丢失;PAGE图谱中三条酶活性带成为四条酶活性带;等电点下降;680nm处表征二价铜光学性质的可见光吸收减弱;紫外吸收增加,表现为增色效应;内源性荧光减弱;在含有3.0mol/LKCl的PH3.8—5.4琥珀酸缓冲液中溶解度下降;酶对胰蛋白酶水解的敏感性增加。

Effect of Hydrogen Peroxide on the Activity and Physicochemical Properties of Yak Superoxide Dismutase

Yak erythrocyte superoxide dismutase (SOD)inactivated irreversibly by H_2O_2 was dependent upon its concentration and the exposure time. The physicochemical properties of SOD were changed by the treatment of H_2O_2 as shown by that (1) a new band stained by SOD activity in PAGE pattern was found besides the original three bands, (2) the contents of the copper and zinc in SOD were decreased, (3) the isoelectric point and intrinsic fluorescence of SOD as well as its absorbance at 680nm were also decreased, (4) the ultraviolet absorbance of SOD increased with the increase of H_2O_2 concentration, showing the characteristics of hyperchromic effect, (5) increased hydrophobicity of SOD was found as indicated by loss of its solubility, (6) the susceptibility of SOD to trypsin hydrolysis was increased. It is suggested that the hydroxyl radical yielded by the reaction of H_2O_2 with the copper in the active site of SOD or the metal lost from it may be respossible for the physicochemical properties changes of the treated SOD.