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Bioinorganic Chemistry and Applications
Volume 2011, Article ID 674149, 8 pages
http://dx.doi.org/10.1155/2011/674149
Research Article

Role of Superoxide Anions in the Redox Changes Affecting the Physiologically Occurring Cu(I)-Glutathione Complex

1Nutrition and Food Technology Institute, University of Chile, Santiago 7830489, Chile
2Faculty of Chemical and Pharmaceutical Sciences, University of Chile, Santiago 8380492, Chile
3Facultad de Química, Pontificia Universidad Católica de Chile, Santiago 6094411, Chile

Received 7 June 2011; Accepted 15 July 2011

Academic Editor: Zhe-Sheng Chen

Copyright © 2011 Hernán Speisky et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The physiologically occurring copper-glutathione complex, [Cu(I)-[GSH]2], has the ability to react continually with oxygen, generating superoxide anions ( O 2 ). We addressed here the effects that superoxide removal has on the redox state of Cu(I) and GSH present in such complex and assessed the formation of Cu(II)-GSSG as a final oxidation product. In addition, we investigated the potential of a source of O 2 external to the Cu(I)-[GSH]2 complex to prevent its oxidation. Removal of O 2 from a Cu(I)-[GSH]2-containing solution, whether spontaneous or Tempol-induced, led to time-dependent losses in GSH that were greater than those affecting the metal. The losses in GSH were not accompanied by increments in GSSG but were largely accounted for by the cumulative formation of Cu(II)-GSSG molecules. Notably, the redox changes in Cu(I) and GSH were totally prevented when Cu(I)-[GSH]2 was coincubated with hypoxanthine/xanthine oxidase. Data suggest that the generation of O 2 by Cu(I)-[GSH]2 implies the obliged formation of an intermediate whose subsequent oxidation into Cu(II)-GSSG or back reduction into Cu(I)-[GSH]2 is favoured by either the removal or the addition of O 2 , respectively.