韭菜线粒体锰超氧化物歧化酶纯化及性质研究

PURIFICATION AND PROPERTIES OF MANGANESE SUPEROXIDE DISMUTASE IN LEEK MITOCHONDRIA

摘要: 经硫酸铵沉淀、DEAE－Sephacel层析和SephadexG－200凝胶过滤,将韭菜线粒体SOD纯化到均一程度。从6000g韭菜叶片线粒体中纯化得到2．5mg酶,酶比活力达1200U／mg蛋白。该酶对KCN和H₂O₂都不敏感,热稳定性弱,紫外光区吸收峰在280um,凝胶过滤法测得其分子量为82000D,SDS－PAGE法测得其亚基分子量为22000D,DNS法测得其N-末端氨基酸为缬氨酸。上述结果表明该酶是由4个相同亚基组成的Mn－SOD。

Abstract: Asuperoxide dismutase from leek mitochondria has been purified to homogeneith by ammonium sulfate fraction, DEAE-Sephacel chromotography and Sephadex G-200 gel filtration.2.5 mg purified enzyme was obtained from 6000 g leaves.The specific activity of the purified enzyme is 1200 U/mg protein.The enzyme is not sensitive to inhibitors:KCN nad H₂O₂.It has good heat .stability.The largest amount of ultraviolet absorption is at 280 urn.The molecular weight of the enzyme is about 82000 Das assayed by Sephadex G-200 gel filtration,that of the enzyme subunit is about 22000 Das tested by SDS-polyacrylamide gel electrophoresis.The N-terminal amine acid of the enzyme is valine as tested by DNS-CI.These results show the enzyme is a manganese superoxide.