Some sulfate-reducing and microaerophilic bacteria rely on the enzyme superoxide reductase (SOR) to eliminate the toxic superoxide anion radical (O2*-). SOR catalyses the one-electron reduction of O2*- to hydrogen peroxide at a nonheme ferrous iron center. The structures of Desulfoarculus baarsii SOR (mutant E47A) alone and in complex with ferrocyanide were solved to 1.15 and 1.7 A resolution, respectively. The latter structure, the first ever reported of a complex between ferrocyanide and a protein, reveals that this organo-metallic compound entirely plugs the SOR active site, coordinating the active iron through a bent cyano bridge. The subtle structural differences between the mixed-valence and the fully reduced SOR-ferrocyanide adducts were investigated by taking advantage of the photoelectrons induced by X-rays. The results reveal that photo-reduction from Fe(III) to Fe(II) of the iron center, a very rapid process under a powerful synchrotron beam, induces an expansion of the SOR active site.
Structure of superoxide reductase bound to ferrocyanide and active site expansion upon X-ray-induced photo-reduction.
Virgile Adam,A. Royant,V. Nivière,F. P. Molina-Heredia,D. Bourgeois
Published 2004 in Structure
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- Publication year
2004
- Venue
Structure
- Publication date
2004-09-01
- Fields of study
Biology, Medicine, Chemistry
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Semantic Scholar, PubMed
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