Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The . gov means it’s official. Federal government websites often end in . gov or . mil. Before sharing sensitive information, make sure you’re on a federal government site. VSports app下载.

Https

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely. V体育官网.

. 2010 Apr 19;49(8):3618-28.
doi: 10.1021/ic901891n.

Oxygen activation at mononuclear nonheme iron centers: a superoxo perspective

Anusree Mukherjee  1 , Matthew A Cranswick, Mrinmoy Chakrabarti, Tapan K Paine, Kiyoshi Fujisawa, Eckard Münck, Lawrence Que Jr
Affiliations

Oxygen activation at mononuclear nonheme iron centers: a superoxo perspective (VSports)

Anusree Mukherjee et al. Inorg Chem. .

Abstract

Dioxygen (O(2)) activation by iron enzymes is responsible for many metabolically important transformations in biology. Often a high-valent iron oxo oxidant is proposed to form upon O(2) activation at a mononuclear nonheme iron center, presumably via intervening iron superoxo and iron peroxo species VSports手机版. While iron(IV) oxo intermediates have been trapped and characterized in enzymes and models, less is known of the putative iron(III) superoxo species. Utilizing a synthetic model for the 2-oxoglutarate-dependent monoiron enzymes, [(Tp(iPr2))Fe(II)(O(2)CC(O)CH(3))], we have obtained indirect evidence for the formation of the putative iron(III) superoxo species, which can undergo one-electron reduction, hydrogen-atom transfer, or conversion to an iron(IV) oxo species, depending on the reaction conditions. These results demonstrate the various roles that the iron(III) superoxo species can play in the course of O(2) activation at a nonheme iron center. .

PubMed Disclaimer

Figures

Figure 1
Figure 1
Active site structures of the O2 adducts of nonheme iron enzymes that have been structurally characterized by X-ray crystallography (orange Fe, grey C, red O, blue N, green Cl). A) The end-on O2 adduct of 3-hydroxyanthranilate-3,4-dioxygenase from R. metallidurans complexed with an inhibitor (1YFW.pdb). B) The side-on O2 adduct NDO from Pseudomonas sp. in the presence of the substrate analog indole (1O7N.pdb). C) and D) The side-on O2 adduct of the HPCD-4-nitrocatechol complex of B. fuscum found in subunit C and the subsequent alkylperoxo intermediate found in subunits B and D, respectively (2IGA.pdb).
Figure 2
Figure 2
UV-Vis spectra in MeCN of 1 (black solid line), 2 (blue dashed-dotted line), the yellow solution obtained upon oxygenation (red dashed line) and the solution obtained upon oxygenation in the presence of THT (red solid line). Inset shows the corresponding magnified spectra in the visible region.
Figure 3
Figure 3
ORTEP plots for [Fe(TpiPr2)(PRV)(MeOH)] (1) and [Fe(TpiPr2)(BF)] (2). Hydrogen atoms are omitted for clarity.
Figure 4
Figure 4
Top: ESI-MS spectrum of 1 after oxygenation but prior to acid treatment. Bottom: 1H-NMR spectrum in the 5.2–6.2-ppm region of the pyrazoles in CDCl3 obtained from the reaction of 1 with O2 after acid treatment to decompose the TpiPr2* ligand (|-marked peaks arise from 3-isopropenyl-5-isopropylpyrazole; the peak at 5.90 ppm is the 4-H of the 3,5-diisopropylpyrazole).
Figure 5
Figure 5
Oxygenation of 1 mM [FeII(TpiPr2)(PRV)] (1) (dashed line) at −40°C in MeCN resulting in the formation of a green chromophore (solid line) that is assigned to a (μ-1,2-peroxo)diiron(III) complex.
Figure 6
Figure 6
Resonance Raman spectra using λex = 647.1 nm of the green chromophore from the oxygenation of 1 at −40 °C in MeCN with 16O2 (top) and 18O2 (bottom). Solvent peaks are denoted as “S” and the asterisk denotes a laser plasma line.
Figure 7
Figure 7
Mössbauer spectra of the green solution obtained from the oxygenation of 1 in MeCN at −40 °C. (A) Spectrum recorded for B = 0. The solid line outlines the contribution of the peroxo intermediate (45% of Fe). (B) and (C) Spectra of the peroxo intermediate recorded in a parallel field of B = 8.0 T at the temperatures indicated; features arising from the FeII and mononuclear FeIII species were removed as described in Supporting Information. Solid lines in (B) and (C) are spectral simulations for J = 70 cm−1. Hyperfine parameters are: A0/gnβn = −21 T, ΔEQ = +1.32 mm/s, η = 1, and δ = 0.65 mm/s for both sites; the Hamiltonian is given in SI.
Figure 8
Figure 8
Oxygenation of 1 mM [Fe(TpiPr2)PRV](black line) at −40°C in MeCN in the presence of 1 equiv TBP-H in a 1-cm cuvette. Red lines show the growth of TBP• features.
Scheme 1
Scheme 1
General mechanism for 2-OG-dependent iron enzymes
Scheme 2
Scheme 2
Various proposed roles for the initial iron-dioxygen adducts in reaction pathways of 2-His-1-carboxylate iron enzymes.
Scheme 3
Scheme 3
Ligands.
Scheme 4
Scheme 4
Reactions of [FeII(TpiPr2)X] complexes with dioxygen.
See this image and copyright information in PMC

References (VSports app下载)

    1. Solomon EI, Brunold TC, Davis MI, Kemsley JN, Lee SK, Lehnert N, Neese F, Skulan AJ, Yang YS, Zhou J. Chem Rev. 2000;100:235–349. - PubMed (V体育ios版)
    1. Costas M, Mehn MP, Jensen MP, Que L., Jr Chem Rev. 2004;104:939–986. - PubMed
    1. Hausinger RP. Crit Rev Biochem Mol Biol. 2004;39:21–68. - PubMed
    1. Kovaleva EG, Lipscomb JD. Nature Chem Biol. 2008;4:186–193. - PMC - PubMed
    1. Loenarz C, Schofield CJ. Nature Chem Biol. 2008;4:152–156. - PubMed

Publication types

MeSH terms

LinkOut - more resources