Detoxification of superoxide without production of H2O2: antioxidant activity of superoxide reductase complexed with ferrocyanide.

Abstract : The superoxide radical O(2)(-.) is a toxic by-product of oxygen metabolism. Two O(2)(-.) detoxifying enzymes have been described so far, superoxide dismutase and superoxide reductase (SOR), both forming H2O2 as a reaction product. Recently, the SOR active site, a ferrous iron in a [Fe(2+) (N-His)(4) (S-Cys)] pentacoordination, was shown to have the ability to form a complex with the organometallic compound ferrocyanide. Here, we have investigated in detail the reactivity of the SOR-ferrocyanide complex with O(2)(-.) by pulse and gamma-ray radiolysis, infrared, and UV-visible spectroscopies. The complex reacts very efficiently with O(2)(-.). However, the presence of the ferrocyanide adduct markedly modifies the reaction mechanism of SOR, with the formation of transient intermediates different from those observed for SOR alone. A one-electron redox chemistry appears to be carried out by the ferrocyanide moiety of the complex, whereas the SOR iron site remains in the reduced state. Surprisingly, the toxic H2O2 species is no longer the reaction product. Accordingly, in vivo experiments showed that formation of the SOR-ferrocyanide complex increased the antioxidant capabilities of SOR expressed in an Escherichia coli sodA sodB recA mutant strain. Altogether, these data describe an unprecedented O(2)(-.) detoxification activity, catalyzed by the SOR-ferrocyanide complex, which does not conduct to the production of the toxic H2O2 species.
Type de document :
Article dans une revue
Proceedings of the National Academy of Sciences of the United States of America , National Academy of Sciences, 2006, pp.14750-5
Liste complète des métadonnées

Littérature citée [9 références]  Voir  Masquer  Télécharger

http://hal.univ-grenoble-alpes.fr/hal-01075778
Contributeur : Vincent Niviere <>
Soumis le : lundi 20 octobre 2014 - 11:16:11
Dernière modification le : jeudi 11 janvier 2018 - 06:21:13
Document(s) archivé(s) le : mercredi 21 janvier 2015 - 10:36:20

Fichier

Manuscript complet.pdf
Fichiers produits par l'(les) auteur(s)

Identifiants

Collections

Citation

Fernando P Molina-Heredia, Chantal Houée-Levin, Catherine Berthomieu, Danièle Touati, Emilie Tremey, et al.. Detoxification of superoxide without production of H2O2: antioxidant activity of superoxide reductase complexed with ferrocyanide.. Proceedings of the National Academy of Sciences of the United States of America , National Academy of Sciences, 2006, pp.14750-5. 〈hal-01075778〉

Partager

Métriques

Consultations de la notice

255

Téléchargements de fichiers

58