Hydroperoxide reduction by thioredoxin-specific glutathione peroxidase isoenzymes of Arabidopsis thaliana
Hydroperoxide reduction by thioredoxin-specific glutathione peroxidase isoenzymes of Arabidopsis thaliana
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DOI：
10.1111/j.1742-4658.2006.05548.x
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发表时间：
2006-12-01
期刊：
影响因子：
5.4
通讯作者：
Shigeoka, Shigeru
中科院分区：
文献类型：
--
作者：
Iqbal, Aqib;Yabuta, Yukinori;Shigeoka, Shigeru
拟南芥含有八个谷胱甘肽过氧化物酶（GPX）同源物（AtGPX 1 -8）。在大肠杆菌中表达了4种不同亚细胞分布的成熟GPX同工酶AtGPX 1、AtGPX-2、AtGPX-5和AtGPX-6，并对其进行了鉴定。有趣的是，这些重组蛋白能够使用硫氧还蛋白而不是谷胱甘肽或NADPH作为电子供体来还原H2 O2、氢过氧化枯烯、磷脂酰胆碱和亚油酸氢过氧化物。重组蛋白对H_2O_2的还原活性比对过氧化氢异丙苯的还原活性高2-7倍。硫氧还蛋白和H2 O2的Km值分别为2.2-4.0和14.0-25.4 μ M。这些发现表明，GPX同工酶的功能，解毒H2 O2和有机氢过氧化物使用硫氧还蛋白在体内，也可能参与调节细胞的氧化还原稳态，通过维持硫醇/二硫化物或NADPH/NADP平衡。
Arabidopsis thaliana contains eight glutathione peroxidase (GPX) homologs (AtGPX1-8). Four mature GPX isoenzymes with different subcellular distributions, AtGPX1, -2, -5 and -6, were overexpressed in Escherichia coli and characterized. Interestingly, these recombinant proteins were able to reduce H2O2, cumene hydroperoxide, phosphatidylcholine and linoleic acid hydroperoxides using thioredoxin but not glutathione or NADPH as an electron donor. The reduction activities of the recombinant proteins with H2O2 were 2-7 times higher than those with cumene hydroperoxide. K-m values for thioredoxin and H2O2 were 2.2-4.0 and 14.0-25.4 mu M, respectively. These finding suggest that GPX isoenzymes may function to detoxify H2O2 and organic hydroperoxides using thioredoxin in vivo and may also be involved in regulation of the cellular redox homeostasis by maintaining the thiol/disulfide or NADPH/NADP balance.