Cu(I)-glutathione complex: a potential source of superoxide radicals generation |
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Authors: | Speisky Hernán Gómez Maritza Carrasco-Pozo Catalina Pastene Edgar Lopez-Alarcón Camilo Olea-Azar Claudio |
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Institution: | Nutrition and Food Technology Institute, University of Chile, Macul 5540, Macul, PO Box 138-11, Santiago, Chile. hspeisky@inta.cl |
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Abstract: | Cu(2+) ions and GSH molecules interact swiftly to form the complex Cu(I)-glutathione. We investigated the potential capacity of such complex to reduce molecular oxygen. The addition of SOD to a solution containing Cu(I)-glutathione led to a sustained decline of the basal oxygen level. Such effect was partially reverted by the addition of catalase. The complex was able to induce the reduction of cytochrome c and the oxidation of dyhydroethidium into 2-hydroxyethidium. Both effects were totally blocked by SOD. The ability of the complex to generate superoxide radicals was confirmed by EPR spin-trapping. Cu(I)-glutathione induces no oxidation of fluorescein, a hydroxyl radical-sensitive probe. We conclude that in solutions containing the complex, oxygen is continually reduced into superoxide, and that-in absence of interceptors-the latter radicals are quantitatively re-oxidized into molecular oxygen. We suggest that, by functioning as a continuous source of superoxide, the complex could potentially affect a broad range of susceptible biological targets. |
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