桑叶超氧化物歧化酶的提纯和性质的研究

Research on Purity and Features of Superoxide Dismutase of Mulbery Leaf

桑叶超氧化物歧化酶（Ｓｕｐｅｒｏｘｉｄｅｄｉｓｍｕｔａｓｅ，ＳＯＤ）能抑制肾上腺素的自动氧化和三氯硝基四氮唑蓝（ＮＢＴ）的光化还原，可以根据ＳＯＤ对肾上腺素的自动氧化的抑制作用为酶活性的定量测定。桑叶ＳＯＤ活性能被ＫＣＮ抑制但不受氯仿—乙醇影响，这表明桑叶ＳＯＤ为Ｃｕ－ＺｎＳＯＤ。它的粗提液经聚丙烯酰胺凝胶电泳及ＮＢＴ的酶活性染色，在蓝色背景上有两条无色透明的同工酶谱带。桑叶粗提液经纯化比活提高２．７倍，其分子量为３５０００，纯化后的桑叶ＳＯＤ有同样的光吸收波谱。

The mulbery leaf SOD can inhibit autoxidation of epinephrine and NBT photoreduetion.The enzyme quatity can be determined from the amount that inhibits the epinephrine autoxidation.The enzymatic activity is inhibited by KCN and is not affected by chioroform-enthanol,which indicates that mulbery SOD is CuZn-SOD.The crude extract presents two bands using polyacrylamide gel electrophoresis and NBT enzymatic activity stain.The enzymatic activity (units/mg) is increased by 2 7 times after the crude extract was purified,and the molecular weight is 35 000.