Modeling the active site of non-heme iron proteins: Synthesis and characterization of carboxylate-bridged diiron(II) complexes

Iron-containing zeolites exhibit unprecedented reactivity in the low-temperature hydroxylation of methane to form methanol. Reactivity occurs at a mononuclear ferrous active site, α-Fe(II), that is activated by N2O to form the reactive intermediate α-O. This has been defined as an Fe(IV)=O species. Using nuclear resonance vibrational spectroscopy coupled to X-ray absorption spectroscopy, we probe the bonding interaction between the iron center, its zeolite lattice-derived ligands, and the reactive oxygen. α-O is found to contain an unusually strong Fe(IV)=O bond resulting from a constrained coordination geometry enforced by the zeolite lattice. Density functional theory calculations clarify how the experimentally determined geometric structure of the active site leads to an electronic structure that is highly activated to perform H-atom abstraction.

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Synthesis and characterization of a family of binuclear non-heme iron monooxygenase model compounds: Evidence for a “phenolate/amide carbonyl (PAC) shift” upon oxidation

Inorganica Chimica Acta ◽

10.1016/j.ica.2008.09.036 ◽

2009 ◽

Vol 362 (7) ◽

pp. 2136-2150 ◽

Cited By ~ 15

Author(s):

Patrick J. Cappillino ◽

Paul C. Tarves ◽

Gerard T. Rowe ◽

Andrew J. Lewis ◽

Mark Harvey ◽

...

Keyword(s):

Heme Iron ◽

Synthesis And Characterization ◽

Model Compounds ◽

Non Heme Iron ◽

Amide Carbonyl

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Monomeric Carboxylate Ferrous Complexes as Models for the Dioxygen Binding Sites in Non-Heme Iron Proteins. The Reversible Formation and Characterization of .mu.-Peroxo Diferric Complexes

Journal of the American Chemical Society ◽

10.1021/ja00099a025 ◽

1994 ◽

Vol 116 (20) ◽

pp. 9071-9085 ◽

Cited By ~ 83

Author(s):

Nobumasa Kitajima ◽

Nobuchika Tamura ◽

Hironobu Amagai ◽

Hideno Fukui ◽

Yoshihiko Moro-oka ◽

...

Keyword(s):

Binding Sites ◽

Heme Iron ◽

Iron Proteins ◽

Non Heme Iron ◽

Reversible Formation

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Synthesis and characterization of two binuclear iron(III) complexes of aminoethanol derivatives of aminophenol as models for non-heme iron enzymes active sites

Polyhedron ◽

10.1016/j.poly.2011.01.019 ◽

2011 ◽

Vol 30 (6) ◽

pp. 1143-1148 ◽

Cited By ~ 12

Author(s):

Elham Safaei ◽

Iraj Saberikia ◽

Andrzej Wojtczak ◽

Zvonko Jagličić ◽

Anna Kozakiewicz

Keyword(s):

Active Sites ◽

Heme Iron ◽

Synthesis And Characterization ◽

Non Heme Iron ◽

Iron Enzymes ◽

Derivatives Of ◽

Binuclear Iron

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Synthesis and Characterization of the Benzoylformato Ferrous Complexes with the Hindered Tris(pyrazolyl)borate Ligand as a Structural Model for Mononuclear Non-Heme Iron Enzymes†

Inorganic Chemistry ◽

10.1021/ic960903m ◽

1997 ◽

Vol 36 (20) ◽

pp. 4539-4547 ◽

Cited By ~ 43

Author(s):

Shiro Hikichi ◽

Tamako Ogihara ◽

Kiyoshi Fujisawa ◽

Nobumasa Kitajima ◽

Munetaka Akita ◽

...

Keyword(s):

Structural Model ◽

Heme Iron ◽

Synthesis And Characterization ◽

Non Heme Iron ◽

Iron Enzymes

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Strongly Coupled Redox-Linked Conformational Switching at the Active Site of the Non-Heme Iron-Dependent Dioxygenase, TauD

10.26434/chemrxiv.9461462 ◽

2019 ◽

Author(s):

Christopher John ◽

Greg M. Swain ◽

Robert P. Hausinger ◽

Denis A. Proshlyakov

Keyword(s):

Active Site ◽

Structural Model ◽

Heme Iron ◽

Chemical Transformations ◽

Experimental Conditions ◽

Strongly Coupled ◽

Non Heme Iron ◽

Reversible Redox ◽

Wide Range ◽

Complex Structural

2-Oxoglutarate (2OG)-dependent dioxygenases catalyze C-H activation while performing a wide range of chemical transformations. In contrast to their heme analogues, non-heme iron centers afford greater structural flexibility with important implications for their diverse catalytic mechanisms. We characterize an <i>in situ</i> structural model of the putative transient ferric intermediate of 2OG:taurine dioxygenase (TauD) by using a combination of spectroelectrochemical and semi-empirical computational methods, demonstrating that the Fe (III/II) transition involves a substantial, fully reversible, redox-linked conformational change at the active site. This rearrangement alters the apparent redox potential of the active site between -127 mV for reduction of the ferric state and 171 mV for oxidation of the ferrous state of the 2OG-Fe-TauD complex. Structural perturbations exhibit limited sensitivity to mediator concentrations and potential pulse duration. Similar changes were observed in the Fe-TauD and taurine-2OG-Fe-TauD complexes, thus attributing the reorganization to the protein moiety rather than the cosubstrates. Redox difference infrared spectra indicate a reorganization of the protein backbone in addition to the involvement of carboxylate and histidine ligands. Quantitative modeling of the transient redox response using two alternative reaction schemes across a variety of experimental conditions strongly supports the proposal for intrinsic protein reorganization as the origin of the experimental observations.

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