菠菜铁型超氧化物歧化酶的纯化及性质

PURIFICATION AND PROPERTIES OF AN IRO CONTAINING SUPEROXIDE DISMUTASE FROM SPINACH LEAVES,SPINACEA OLERACEA

用聚丙烯酰胺梯度凝胶电泳法检测出菠菜ＳＯＤ同工酶谱带中含３ 条Ｆｅ－ＳＯＤ活性带。菠菜叶Ｆｅ－ＳＯＤ粗提液经硫酸铵分部沉淀，ＤＥＡＥ－纤维素－Ａ５２和Ｓｅｐｈａｄｅｘ Ｇ－１００ 柱层析，纯化出单一的Ｆｅ－ＳＯＤ活性带。纯化酶的分子量为４２．６ ｋＤ，亚基分子量为２１ ｋＤ。对金属元素的分析表明，该酶每分子含２．６ 个Ｆｅ 原子。该酶紫外区最大吸收峰为２７８ ｎｍ ，等电点为４．６，氨基酸组成和其它来源的Ｆｅ－ＳＯＤ类似。

Iron superoxide dismutase was found in the crude extract from leaves of Spinacea oleracea after gradient PAGE analysis.The enzyme was isolated and purified to homogeneity by using ammonium sulfate fractionation followed by DEAE Cellulose A 52 chromatography and Sephadex G 100 gel filtration.The molecular mass of the purified Fe SOD is about 42.6 kD,and its subunit molecular mass is about 21 kD .Metal analysis reveals that the protein contains about 2.6 gram atoms of iron per molecule.The purified enzyme exhibits one absorption maximum in the ultraviolet at 278 nm with a low shoulder of absorption at 260 nm and 290 nm.Its isoelectric point is 4.6.In the aspects of amino acid composition,the enzyme from spinach is most similar to Fe SOD from other sources.