Two GPX-like proteins from Lycopersicon esculentum and Helianthus annuus are antioxidant enzymes with phospholipid hydroperoxide glutathione peroxidase and thioredoxin peroxidase activities
Two GPX-like proteins from Lycopersicon esculentum and Helianthus annuus are antioxidant enzymes with phospholipid hydroperoxide glutathione peroxidase and thioredoxin peroxidase activities
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DOI：
10.1046/j.1432-1033.2002.02905.x
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发表时间：
2002-05-01
期刊：
影响因子：
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通讯作者：
Roeckel-Drevet, P
中科院分区：
文献类型：
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作者：
Herbette, S;Lenne, C;Roeckel-Drevet, P
本研究研究了来自番茄的GPXle1和来自向日葵的GPXha2两个推测的植物gpx的酶功能，它们与哺乳动物磷脂氢过氧化物谷胱甘肽过氧化物酶（PHGPX）序列一致。在大肠杆菌中表达的纯化重组蛋白通过还原烷基、脂肪酸和磷脂氢过氧化物显示出PHGPX活性，但在谷胱甘肽存在下不具有过氧化氢活性。有趣的是，重组GPXle1和GPXha2蛋白也使用硫氧还蛋白作为还原底物还原烷基、脂肪酸和磷脂氢过氧化物以及过氧化氢。此外，硫氧还蛋白过氧化物酶（TPX）活性在效率和底物亲和力方面均高于PHGPX活性，这可以从它们各自的V-max和K-m值中看出。因此，我们认为这两种植物gpx样蛋白是具有PHGPX和TPX活性的抗氧化酶。
This study investigated the enzymatic function of two putative plant GPXs, GPXle1 from Lycopersicon esculentum and GPXha2 from Helianthus annuus , which show sequence identities with the mammalian phospholipid hydroperoxide glutathione peroxidase (PHGPX). Both purified recombinant proteins expressed in Escherichia coli show PHGPX activity by reducing alkyl, fatty acid and phospholipid hydroperoxides but not hydrogen peroxide in the presence of glutathione. Interestingly, both recombinant GPXle1 and GPXha2 proteins also reduce alkyl, fatty acid and phospholipid hydroperoxides as well as hydrogen peroxide using thioredoxin as reducing substrate. Moreover, thioredoxin peroxidase (TPX) activities were found to be higher than PHGPX activities in terms of efficiency and substrate affinities, as revealed by their respective V-max and K-m values. We therefore conclude that these two plant GPX-like proteins are antioxidant enzymes showing PHGPX and TPX activities.