Groupe de Recherche Inter-Universitaire en Limnologie, Département de Sciences Biologiques, Université de Montréal, CP 6128, Succursale Centre-Ville, Pavillon Marie-Victorin, Montréal, Québec, Canada.
Chemosphere. 2010 Sep;80(11):1314-20. doi: 10.1016/j.chemosphere.2010.06.041. Epub 2010 Jul 2.
The behavior and stability of dissolved reduced glutathione (GSH), an environmental antioxidant and metal transporter, is poorly known in natural waters. Glutathione oxidation rates were determined in both fresh- and brackish waters artificially submitted to different radiation wavebands. Photo-oxidation of GSH followed pseudo-first order kinetics, with half-lives ranging from 4 to 30h in natural freshwater, and from 1.6 to 7h in saltwater, with generally shorter persistence in UV-irradiated surface waters than in dark treatments. Chloride was shown to indirectly promote GSH photo-oxidation, probably through its role in the formation of radicals. The addition of Cu(II) to synthetic waters resulted in the rapid oxidation of GSH. The addition of Hg(II), a metal with strong affinity for thiols, protected GSH from oxidation by Cu(II) in the dark, but not under UV radiation. We conclude that UV-induced photo-oxidation is a key process altering the fate of GSH in natural waters. Also, the formation of stable GSH-Hg complexes could increase the bioavailability of Hg towards microorganisms in aquatic systems.
溶解态还原型谷胱甘肽（GSH）是一种环境抗氧化剂和金属转运体，其在天然水体中的行为和稳定性知之甚少。本研究在人工暴露于不同辐射波段的淡水和咸水中，测定了 GSH 的氧化速率。GSH 的光氧化遵循准一级动力学，在天然淡水中的半衰期范围为 4-30h，在海水中为 1.6-7h，在紫外线辐照的地表水比黑暗处理中的半衰期更短。结果表明，氯离子可能通过形成自由基而间接促进 GSH 的光氧化。向合成水中添加 Cu(II)会导致 GSH 的快速氧化。向 Hg(II)（一种与巯基具有强亲和力的金属）添加 Hg(II)会在黑暗中保护 GSH 不被 Cu(II)氧化，但在紫外线辐射下则不会。本研究得出结论，紫外线诱导的光氧化是改变天然水中 GSH 命运的关键过程。此外，形成稳定的 GSH-Hg 配合物可以增加汞在水生系统中对微生物的生物利用度。
