Proteins containing oxo-bridged dinuclear iron centers: a bioinorganic perspective

The active site of the cyanide‐resistant oxidase from plant mitochondria contains a binuclear iron center

“…Finally, a bridging hydroxo atom is incorporated into the alternative oxidase active site model (Fig. 1B) to account for the lack of absorbance above 300 nm, analogous to methane monooxygenase [19,22]. The four-helical bundle shown in Fig.…”

“…Based on physical properties and conserved amino acid sequence motifs, the active site of the hydroxylase subunit contains a bridged binuclear iron center having structural features analogous to other Fe-O-Fe metalloproteins, such as hemerythrin, the R2 subunit of ribonucleotide reductase and soluble eukaryotic fatty acyl desaturases [19 21]. In all of these enzymes, the oxidized protein contains antiferromagnetically coupled high-spin Fe(IIl) atoms [19,22]. In the fully reduced state, both iron atoms are Fe(II) and remain coupled, although probably ferromagnetically [19].…”

Resonance Raman spectroscopy of FeII FeIII and FeIII FeIII model complexes containing an unsymmetrical dinucleating ligand: a biomimetic redox pair for uteroferrin

“…8, 2006 inorganic coordination compounds, 5 metal-containing proteins [6][7][8] and their biomimetic analogues. [9][10][11][12][13][14][15][16][17][18] PAP's and related systems have also been studied by this technique, [19][20][21][22][23][24][25] aiming to characterize the chromophoric moiety for improved understanding of their electronic structure. The visible chromophore in the PAP enzyme has been associated with a tyrosinate to Fe III charge-transfer transition.…”

“…They contain a dinuclear core Fe III M II (M = Fe, Mn or Zn) in their active sites, which are able to catalyze the hydrolysis of a variety of phosphoric acid esters and anhydrides within the pH range 4-7. [1][2][3] In particular, the core Fe II Fe III is present in uteroferrin, a PAP from porcine uterus that is involved in the hydrolysis of orthophosphate monoesters and the regulation of the levels of phosphate at pH 4.9-6.0 . 1,4 The reduced form of the enzyme is pink (λ max =505-510 nm, ε ≈ 4000 L mol -1 cm -1 /Fe 2 ), and is active for hydrolysis, while the purple form, Fe III Fe III (λ max =550-570 nm, ε ≈ 4000 L mol -1 cm -1 / Fe 2 ) is inactive.…”

“…[1][2][3] In particular, the core Fe II Fe III is present in uteroferrin, a PAP from porcine uterus that is involved in the hydrolysis of orthophosphate monoesters and the regulation of the levels of phosphate at pH 4.9-6.0 . 1,4 The reduced form of the enzyme is pink (λ max =505-510 nm, ε ≈ 4000 L mol -1 cm -1 /Fe 2 ), and is active for hydrolysis, while the purple form, Fe III Fe III (λ max =550-570 nm, ε ≈ 4000 L mol -1 cm -1 / Fe 2 ) is inactive. 4 The similarity between the molar absorptivities of these two forms comes from the fact that the reduced iron is not part of the chromophoric group (tyrosinate-Fe III ).…”