PURIFICATION AND PROPERTIES OF GLUTATHIONE PEROXIDASE FROM HUMAN PLACENTA
PURIFICATION AND PROPERTIES OF GLUTATHIONE PEROXIDASE FROM HUMAN PLACENTA
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DOI：
10.1042/bj1770471
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发表时间：
1979-01-01
影响因子：
4.1
通讯作者：
SRIVASTAVA, SK
中科院分区：
文献类型：
--
作者：
AWASTHI, YC;DAO, DD;SRIVASTAVA, SK
采用(NH4)2SO4沉淀、离子交换层析、Sephadex凝胶过滤和制备性聚丙烯酰胺圆盘凝胶电泳法，从人胎盘中分离纯化了谷胱甘肽过氧化物酶(GSH-H_2O_2氧化还原酶，EC 1.11.1.9)。人胎盘谷胱甘肽过氧化物酶是一种四聚体，具有4G原子的硒/摩尔蛋白质。该酶的分子量约为85000，亚基大小约为22,000。对该酶的动力学性质进行了描述。与氰化物孵育时，谷胱甘肽过氧化物酶完全不可逆转地失活，硒以低分子片断的形式释放。还原型谷胱甘肽、β-巯基乙醇和二硫苏糖醇可保护酶免受氰化物的失活和硒的释放。人胎盘谷胱甘肽过氧化物酶的性质与我们早些时候报道的人红细胞同工酶A的性质相似。我们早些时候报道的人类红细胞中存在同工酶B，但在胎盘中没有检测到。此外，人胎盘中也不存在与硒无关的谷胱甘肽过氧化物酶(同工酶II)，这种酶是异丙苯氢过氧化氢的特异性酶。
Glutathione peroxidase (glutathione–H2O2 oxidoreductase; EC 1.11.1.9) was purified to homogeneity from human placenta by using (NH4)2SO4 precipitation, ion-exchange chromatography, Sephadex gel filtration and preparative polyacrylamide-disc-gel electrophoresis. Glutathione peroxidase from human placenta is a tetramer, having 4g-atoms of selenium/mol of protein. The molecular weight of the enzyme is about 85000 with a subunit size of about 22,000. Kinetic properties of the enzyme are described. On incubation with cyanide, glutathione peroxidase is completely and irreversibly inactivated and selenium is released as a low-molecular-weight fragment. Reduced glutathione, beta-mercaptoethanol and dithiothreitol protect the enzyme from inactivation by cyanide and the release of selenium. Properties of human placental glutathione peroxidase are similar to those of isoenzyme A reported earlier by us from human erythrocytes. The presence of isoenzyme, B, reported earlier by us in human erythrocytes, was not detected in placenta. Also selenium-independent glutathione peroxidase (isoenzyme II), which is specific for cumene hydroperoxide, was not present in human placenta.