极大螺旋藻铁型超氧物歧化酶的纯化及性质

Purification and Properties of Ironcontaining Superoxide Dismutase from Spirulina maxima

极大螺旋藻 Ｓｐｉｒｕｌｉｎａｍａｘｉｍａ藻体ＳＯＤ聚丙烯酰胺梯度凝胶电泳呈现４条同工 酶带， Ｈ_ ２Ｏ_２明显抑制该酶活性， ＫＣＮ对酶活性无影响，确认为 Ｆｅ－ＳＯＤ经硫酸铵分部盐析、离子交 换柱层析及凝胶过滤，纯化到电泳单斑点均－程度．纯化的Ｆｅ－ＳＯＤ分子量为３９．３ＫＤ，亚基分子 量为２０ＫＤ金属元素分析表明，每个亚基含０ ５５个Ｆｅ原子，该酶在紫外区最大吸收峰值为 ２７５．８nｍ、该酶氨基酸组成与蓝、绿藻和高等植物的Ｆｅ－ＳＯＤ相似，但它含有较高的丙氨酸，酸性氨 基酸和碱性氨基酸比值与低等植物及原核生物相近而明显高于高等植物．

The isozyme of SOD in Spirulina maxima with four bands by gradient electrophoresis was identified as Fe--SOD, which was purified by ammonium sulfate fractionation followed by DEAECelluose and Sephadex G-100 column chromatography. The molecular weight of the enzyme is 39. 3KD, and that of its subunit molecular mass is 20KD. Metal analysis showed that the Fe-SOD contains about 0. 55 atom of iron per subunit. The enzyme exhibits one absorption maximum at 275. 8nm. The enzyme activity could be inhibited by H_2O_2 but unaffected by KCN. The Fe-enzyme contains more alanine residues. The ratio of acid amino acid and alkaline amino acid is similar to lower plants and procaryotes, obviously higher than those of higher plants.