Cu(I)-glutathione complex: a potential source of superoxide radicals generation.
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.
Nutrition and Food Technology Institute, University of Chile, Macul 5540, Macul, PO Box 138-11, Santiago, Chile. hspeisky@inta.cl
Hernán
H
Speisky
Maritza
M
Gómez
Catalina
C
Carrasco-Pozo
Edgar
E
Pastene
Camilo
C
Lopez-Alarcón
Claudio
C
Olea-Azar
D000818:Animals; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D003300:Copper / Q000737:chemistry*; D045304:Cytochromes c / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D004996:Ethidium / Q000031:analogs & derivatives / Q000737:chemistry; D019793:Fluorescein / Q000737:chemistry; D005978:Glutathione / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D013481:Superoxides / Q000737:chemistry*
C067883:dihydroethidium; D013481:Superoxides; D003300:Copper; D045304:Cytochromes c; D004996:Ethidium; D005978:Glutathione; D010100:Oxygen; D019793:Fluorescein