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Iron Centre (iron + centre)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

Cloning, purification, crystallization and X-ray crystallographic analysis of Ignicoccus hospitalis neelaredoxin

ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 5 2010
Filipa G. Pinho
Superoxide reductases (SORs) are metalloproteins which constitute the most recently identified oxygen-detoxification system in anaerobic and microaerobic bacteria and archaea. SORs are involved in scavenging superoxide radicals from the cell by catalyzing the reduction of superoxide () to hydrogen peroxide and are characterized by a catalytic nonhaem iron centre coordinated by four histidine ligands and one cysteine ligand. Ignicoccus hospitalis, a hyperthermophilic crenarchaeon, is known to have a neelaredoxin-type SOR that keeps toxic oxygen species levels under control. Blue crystals of recombinant I. hospitalis oxidized neelaredoxin (14.1,kDa, 124 residues) were obtained. These crystals diffracted to 2.4,Å resolution in-house at room temperature and belonged to the hexagonal space group P6222 or P6422, with unit-cell parameters a = b = 108, c = 64,Å. Cell-content analysis indicated the presence of one monomer in the asymmetric unit. [source]

Purification, crystallization and X-ray crystallographic analysis of Archaeoglobus fulgidus neelaredoxin

ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 3 2010
Tiago M. Bandeiras
Neelaredoxins are a type of superoxide reductase (SOR), which are blue 14,kDa metalloproteins with a catalytic nonhaem iron centre coordinated by four histidines and one cysteine in the ferrous form. Anaerobic organisms such as Archaeoglobus fulgidus, a hyperthermophilic sulfate-reducing archaeon, have developed defence mechanisms against toxic oxygen species in which superoxide reductases play a key role. SOR is responsible for scavenging toxic superoxide anion radicals (O2·,), catalysing the one-electron reduction of superoxide to hydrogen peroxide. Crystals of recombinant A. fulgidus neelaredoxin in the oxidized form (13.7,kDa, 125 residues) were obtained using polyethylene glycol and ammonium sulfate. These crystals diffracted to 1.9,Å resolution and belonged to the tetragonal space group P41212, with unit-cell parameters a = b = 75.72, c = 185.44,Å. Cell-content analysis indicated the presence of a tetramer in the asymmetric unit, with a Matthews coefficient (VM) of 2.36,Å3,Da,1 and an estimated solvent content of 48%. The three-dimensional structure was determined by the MAD method and is currently under refinement. [source]

Metal,Metal Electronic Coupling in syn and anti Stereoisomers of Mixed-Valent (FeCp)2 -, (RhL2)2 -, and (FeCp)(RhL2)- as -Indacenediide Ions

CHEMISTRY - A EUROPEAN JOURNAL, Issue 28 2007
Saverio Santi Prof.
Abstract The extent of metal,metal electronic coupling was quantified for a series of syn and anti stereoisomers of (FeCp)2 -, (RhL2)2 - and (FeCp)(RhL2)- (L2=1,5-cyclooctadiene (cod), L=CO) as -indacenediide mixed-valent ions by spectroelectrochemical and DFT studies. The effect of the syn/anti orientation of the metal units with respect to the planar aromatic ligand indicates that electron transfer occurs through the bridge rather than through space. The nature of the metal was found to be crucial: while homobimetallic diiron species are localised valence-trapped ions (Class,II), the dirhodium analogues are almost delocalised mixed-valent ions (borderline and Class,III). Finally, despite their redox asymmetry, even in the heterobimetallic iron,rhodium as -indacenediide complexes, strong metal,metal coupling is present. In fact, oxidation of the iron centre is accompanied by electron transfer from rhodium to iron and formation of a reactive 17-electron rhodium site. syn and anti Fe,Rh as -indacenediide complexes are rare examples of heterobimetallic systems which can be classified as borderline Class,II/Class,III species. [source]

Reversible, Fine Performance Tuning of an Organometallic Molecular Wire by Addition, Ligand Replacement and Removal of Dicobalt Fragments

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 23 2010
Yuya Tanaka
Abstract Communication between the two iron centres in (dithienylethyne)diyl complex 1 can be finely tuned by reversible addition to, ligand replacement at and removal from the C,C moiety in 1 of dicobalt fragments Co2(CO)n(PR3)6,n. Performance analysis reveals that disparate mechanisms are in operation for the two systems. In the case of the dicobalt adducts, indirect communication via the dicobalt steppingstone can be finely tuned by controlling the electronic structure of the dicobalt unit. [source]