硒的生化特性与谷胱甘肽系统

介绍了硒的生理生化特性,重点阐述了硒与谷胱甘肽系统在抗氧化防御体系中的作用以及硒蛋白的研究进展。硒和谷胱甘肽(GSH)系统在氧化防御反应中起着关键性作用。其中GSH的主要功能是直接阻断氧化物生成和促进抗氧化物生成的还原反应;此外,GSH在代谢、细胞信号传导和蛋白质间相互作用中也具有辅助性功能,还可调节机体防御反应。硒在哺乳动物细胞中的保护作用受含硒氨基酸如硒半胱氨酸、硒蛋氨酸的调控。谷胱甘肽过氧化物酶(GSH-Px)的活性位点含有硒半胱氨酸残基。其它含硒蛋白(如硒蛋白P和硫氧还蛋白还原酶)也具有抗氧化特性。合成的有机硒复合物(如Ebselen)在机体氧化应激中是一种极具应用前景的抗氧化剂。硒蛋白和有机硒复合物在预防过亚硝酸盐的生成中也起着重要作用。

The biochemistry of selenium and the glutathione system

In the context of dense against pro-oxidants, selenium and the glutathione (GSH) system play key functions. Major roles of GSH include direct interception of pro-oxidants, as well as a reduction of other antioxidants from their oxidized forms. Furthermore, GSH has ancillary functions, such as metabolism, cell signaling, and protein interactions, that can also mediate defense against oxidants. Protection by selenium in the mammalian cell is mediated by selenol-aminoacids, either as selenocysteine or selenomethionine. The active site of the potent glutathione peroxidase (GSH-Px) contains selenocysteine residues. Moreover, other selenoproteins (e.g. selenoprotein P and thioredoxin reductase) also have been shown to possess antioxidant properties. Synthetic organoselenium compounds (e.g. ebselen) have also shown promise as pharmacologic antioxidants in in vivo models of tissue damage due to oxidative stress. The specific function of selenoproteins and organoselenium compounds in defense against peroxynitrite, by reduction of this potent oxidizing and nitrating species to nitrite, is also discussed. The physiological and biochemical properties of selenium were briefly introduced, and selenium and the glutathione system in the context of antioxidant defense and the progress of selenoproteins were expounded in this context.