Purification and characterization of an iron-containing superoxide dismutase from a eucaryote, Ginkgo biloba.
Purification and characterization of an iron-containing superoxide dismutase from a eucaryote, Ginkgo biloba.
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来自真核生物银杏的含铁超氧化物歧化酶的纯化和表征。
DOI：
10.1016/0003-9861(85)90800-8
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发表时间：
1985
影响因子：
3.9
通讯作者：
M. Salin
中科院分区：
文献类型：
--
作者：
Mary V. Duke;M. Salin
从真核生物银杏叶中纯化出一种对氰化物不敏感的超氧化物歧化酶，使其电泳均匀。该酶的分子量为47，000，由两个大小相等的亚基组成。酶制剂含有两种同工酶，其等电点为5.25和5.15。对EDTA透析后的金属分析显示每分子存在1.4克原子的铁。每个酶分子还检测到大约2克原子的铜和锌，尽管其他螯合剂去除铜对酶活性没有影响。银杏铁超氧化物歧化酶（GinkgoironSuperoxidedismutase，GSOD）定位于叶绿体基质中，但不存在于线粒体中。氨基酸组成的S Δ Q分析表明，银杏铁超氧化物歧化酶与菜豆、芸苔属和大肠杆菌的铁超氧化物歧化酶最相似。这四种酶的蛋白水解消化形成的肽片段进行了定性比较;观察到类似大小的片段，表示可能的同源性区域。
A cyanide-insensitive Superoxide dismutase was purified to electrophoretic homogeneity from leaves of the eucaryote,Ginkgo bilobaL. A molecular mass of 47,000 was determined for the enzyme, which consisted of two subunits of equal size. The enzyme preparation contained two isoenzymes with isoelectric points of 5.25 and 5.15. Metal analysis after dialysis against EDTA revealed the presence of 1.4 gram atoms of iron per molecule. Approximately 2 gram atoms each of copper and zinc per enzyme molecule were also detected, although removal of copper by other chelators had no effect on enzymatic activity. The purifiedGinkgoenzyme exhibited a sensitivity to hydrogen peroxide and insensitivity to cyanide, which is typical of iron-containing superoxide dismutases.Ginkgoiron superoxide dismutase was localized in the stroma of chloroplasts, but was absent from mitochondria. The enzyme fromGinkgowas most similar to iron Superoxide dismutases ofNuphar,Brassica, andEscherichia coliwhen compared on the basis ofSΔQanalysis of amino acid composition. Peptide fragments formed by proteolytic digestion of these four enzymes were compared qualitatively; similar-sized fragments which denote possible areas of homology were observed.