牛血清白蛋白对超氧化物歧化酶的化学修饰

目的：通过化学修饰提高超氧化歧化酶（SOD）的稳定性，考察金属离子在不同浓度下对SOD活性的影响。方法：用戊二醛作为交联剂，用牛血清白蛋白（BSA）将牛红细胞超氧化物歧化酶进行化学修饰，得到SOD的修饰酶。对比研究三种SOD：修饰酶，混合酶及天然酶的理化性质。结果：修饰酶等电点降低，对温度、pH的稳定性较天然酶有很大提高，对胰蛋白酶和胃蛋白酶也表现出很强的耐水解性。二价离子Mg^2 、Mn^2 对天种SOD活力均有不同程度的抵制作用，Ca^2 、Zn^2 、Cu^2 对修饰酶活力有激活作用,一价离子K^ 对三种OSD活力均无明显影响.结论:修饰酶较天然酶的稳定性有很大的提高,加入Ca^2 、Zn^2 、Cu^2 可提高修饰酶的活力。

Chemical Modification of Superoxide Dismutase with Bovine Sermn Albumin

Object:The experiment increased the stability of superoxide dismutase through chemical modification and also assayed the effect of different metal ions in different concentration on the activities of the natural,modified and mixed SOD.Methods:The superoxide dismutase(SOD) of bovine erythrocytes has been linked with bovine serum albumin(BSA) by glutaric dialdehyde.The properties of the modified SOD were studied and compared with the natural SOD and SOD-BSA mixture.Results:The results indicated that the isoelectric point of the modified SOD decreased and the stabilities of heat and pH increased compared with natural SOD.The modified SOD also showed great resistance to the degradation by pepsin and trypsin.The result showed that Mg2+,Mn2+could inhibit the activities of the three SODs above to different extent,Ca2+,Cu2+,Zn2+ could activate the modified SOD,but K+ had no obvious effect.Conclusion:The stabilities of modified SOD have increased greatly compared with natural SOD.And Ca2+,Cu2+,Zn2+ could increase the activity of modified SOD.