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PDBsum entry 1vzi
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Oxidoreductase
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PDB id
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1vzi
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Structure of superoxide reductase bound to ferrocyanide and active site expansion upon x-Ray-Induced photo-Reduction.
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Authors
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V.Adam,
A.Royant,
V.Nivière,
F.P.Molina-Heredia,
D.Bourgeois.
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Ref.
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Structure, 2004,
12,
1729-1740.
[DOI no: ]
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PubMed id
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Abstract
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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.
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Figure 2.
Figure 2. Details of the SOR Active SiteFinal 2F[o] - F[c]
electron density map, contoured at 1.0 s, superimposed onto a
ball-and-stick representation of the active site. Center II iron
and chloride are represented as dark green and lime green
spheres, respectively. Iron coordination is shown by purple
dotted lines. The chloride anion binds tightly only in monomer
A, where Lys48 is highly ordered. In monomer B, a crystalline
contact partially disorders Lys48, thus disrupting the water
network at this location and leading to alternate positions for
the chloride ion, as suggested by an elongated electron density
(data not shown). Figures 2, 5B, 5C, 6, and 7 were prepared with
Bobscript (Esnouf, 1999) and Raster 3D (Merritt and Bacon, 1997).
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The above figure is
reprinted
by permission from Cell Press:
Structure
(2004,
12,
1729-1740)
copyright 2004.
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