EPR Spectroscopic Trapping of the Active Species of Nonheme Iron-Catalyzed Oxidation

2009 ◽  
Vol 131 (31) ◽  
pp. 10798-10799 ◽  
Author(s):  
Oleg Y. Lyakin ◽  
Konstantin P. Bryliakov ◽  
George J. P. Britovsek ◽  
Evgenii P. Talsi
Keyword(s):  
Active Species ◽  
Nonheme Iron ◽  
Catalyzed Oxidation

ChemInform Abstract: Active Species of Nonheme Iron and Manganese-Catalyzed Oxidations

ChemInform ◽  
2013 ◽  
Vol 44 (37) ◽  
pp. no-no
Author(s):  
Oleg Y. Lyakin ◽  
Roman V. Ottenbacher ◽  
Konstantin P. Bryliakov ◽  
Evgenii P. Talsi
Keyword(s):  
Active Species ◽  
Nonheme Iron ◽  
Iron And Manganese

scholarly journals A Comparative Review on the Catalytic Mechanism of Nonheme Iron Hydroxylases and Halogenases

Catalysts ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 314 ◽  
Author(s):  
Amy Timmins ◽  
Sam P. de Visser
Keyword(s):  
Hydrogen Peroxide ◽  
Molecular Oxygen ◽  
Catalytic Mechanism ◽  
Computational Modelling ◽  
Active Species ◽  
Nonheme Iron ◽  
Comparative Review ◽  
Modelling Studies ◽  
Iron Heme ◽  
And Function

Enzymatic halogenation and haloperoxidation are unusual processes in biology; however, a range of halogenases and haloperoxidases exist that are able to transfer an aliphatic or aromatic C–H bond into C–Cl/C–Br. Haloperoxidases utilize hydrogen peroxide, and in a reaction with halides (Cl−/Br−), they react to form hypohalides (OCl−/OBr−) that subsequently react with substrate by halide transfer. There are three types of haloperoxidases, namely the iron-heme, nonheme vanadium, and flavin-dependent haloperoxidases that are reviewed here. In addition, there are the nonheme iron halogenases that show structural and functional similarity to the nonheme iron hydroxylases and form an iron(IV)-oxo active species from a reaction of molecular oxygen with α-ketoglutarate on an iron(II) center. They subsequently transfer a halide (Cl−/Br−) to an aliphatic C–H bond. We review the mechanism and function of nonheme iron halogenases and hydroxylases and show recent computational modelling studies of our group on the hectochlorin biosynthesis enzyme and prolyl-4-hydroxylase as examples of nonheme iron halogenases and hydroxylases. These studies have established the catalytic mechanism of these enzymes and show the importance of substrate and oxidant positioning on the stereo-, chemo- and regioselectivity of the reaction that takes place.

scholarly journals Insights into the mechanistic and synthetic aspects of the Mo/P-catalyzed oxidation of N-heterocycles

2014 ◽  
Vol 12 (19) ◽  
pp. 3026-3036 ◽  
Author(s):  
Oleg V. Larionov ◽  
David Stephens ◽  
Adelphe M. Mfuh ◽  
Hadi D. Arman ◽  
Anastasia S. Naumova ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Active Species ◽  
Catalytically Active ◽  
Synthetic Studies ◽  
Catalyzed Oxidation ◽  
Shed Light

Mechanistic and synthetic studies of the Mo/P-catalyzed N-oxidation of N-heterocycles with hydrogen peroxide shed light on the role and nature of the catalytically active species.

scholarly journals Mechanistic Aspects of Osmium(VIII) Catalyzed Oxidation of L-Tryptophan by Diperiodatocuprate(III) in Aqueous Alkaline Medium: A Kinetic Model

2008 ◽  
Vol 2008 ◽  
pp. 1-5 ◽  
Author(s):  
Nagaraj P. Shetti ◽  
Ragunatharaddi R. Hosamani ◽  
Sharanappa T. Nandibewoor
Keyword(s):  
Kinetic Model ◽  
Alkaline Medium ◽  
Active Species ◽  
Probable Mechanism ◽  
Spot Test ◽  
Spectral Studies ◽  
Aqueous Alkaline Medium ◽  
Unit Order ◽  
First Order ◽  
Catalyzed Oxidation

In presence of osmium(VIII), the reaction between L-tryptophan and diperiodatocuprate(III) DPC in alkaline medium exhibits 1:4 stochiometry (L-tryptophan:DPC). The reaction shows first-order dependence on [DPC] and [osmium(VIII)], less than unit order in both [L-tryptophan] and [alkali], and negative fractional order in [periodate]. The active species of catalyst and oxidant have been identified. The main products were identified by spectral studies and spot test. The probable mechanism was proposed and discussed.

EPR detection of Fe(V)=O active species in nonheme iron-catalyzed oxidations

2012 ◽  
Vol 29 ◽  
pp. 105-108 ◽  
Author(s):  
Oleg Y. Lyakin ◽  
Irene Prat ◽  
Konstantin P. Bryliakov ◽  
Miquel Costas ◽  
Evgenii P. Talsi
Keyword(s):  
Active Species ◽  
Nonheme Iron

scholarly journals Density Functional Theory Study into the Reaction Mechanism of Isonitrile Biosynthesis by the Nonheme Iron Enzyme ScoE

2021 ◽  
Author(s):  
Hafiz Saqib Ali ◽  
Sidra Ghafoor ◽  
Sam P. de Visser
Keyword(s):  
Reaction Mechanism ◽  
Hydrogen Atom ◽  
Proton Transfer ◽  
Active Site ◽  
Density Functional ◽  
Active Species ◽  
Nonheme Iron ◽  
Catalytic Cycle ◽  
Hydrogen Atom Abstraction ◽  
Catalytic Cycles

AbstractThe nonheme iron enzyme ScoE catalyzes the biosynthesis of an isonitrile substituent in a peptide chain. To understand details of the reaction mechanism we created a large active site cluster model of 212 atoms that contains substrate, the active oxidant and the first- and second-coordination sphere of the protein and solvent. Several possible reaction mechanisms were tested and it is shown that isonitrile can only be formed through two consecutive catalytic cycles that both use one molecule of dioxygen and α-ketoglutarate. In both cycles the active species is an iron(IV)-oxo species that in the first reaction cycle reacts through two consecutive hydrogen atom abstraction steps: first from the N–H group and thereafter from the C–H group to desaturate the NH-CH2 bond. The alternative ordering of hydrogen atom abstraction steps was also tested but found to be higher in energy. Moreover, the electronic configurations along that pathway implicate an initial hydride transfer followed by proton transfer. We highlight an active site Lys residue that is shown to donate charge in the transition states and influences the relative barrier heights and bifurcation pathways. A second catalytic cycle of the reaction of iron(IV)-oxo with desaturated substrate starts with hydrogen atom abstraction followed by decarboxylation to give isonitrile directly. The catalytic cycle is completed with a proton transfer to iron(II)-hydroxo to generate the iron(II)-water resting state. The work is compared with experimental observation and previous computational studies on this system and put in a larger perspective of nonheme iron chemistry.

Active Species of Nonheme Iron and Manganese-Catalyzed Oxidations

2013 ◽  
Vol 56 (11) ◽  
pp. 939-949 ◽  
Author(s):  
Oleg Y. Lyakin ◽  
Roman V. Ottenbacher ◽  
Konstantin P. Bryliakov ◽  
Evgenii P. Talsi
Keyword(s):  
Active Species ◽  
Nonheme Iron ◽  
Iron And Manganese

Removal of Refractory Organic Orange IV by Fe-Mn/GAC in the Presence of H2O2

2012 ◽  
Vol 466-467 ◽  
pp. 490-494 ◽  
Author(s):  
Ying Jie Zhang ◽  
Xia Liao ◽  
Shu Fen Xu ◽  
Da Peng Li ◽  
Qing Hu
Keyword(s):  
Reaction Rate ◽  
Removal Rate ◽  
Reaction Rate Constant ◽  
Active Species ◽  
Carbon Particles ◽  
Initial Ph ◽  
Catalytic Reactivity ◽  
Activated Carbon Particles ◽  
Catalyzed Oxidation ◽  
Iron And Manganese

A new heterogeneous catalyst Fe-Mn/GAC (iron and manganese were loaded into activated carbon particles) was prepared, which had a better catalytic reactivity to decompose H2O2 compared with Fe/GAC and Mn/GAC. The removal rate of Orange IV increased more than 10% with this catalyst compared with Fe/GAC and Mn/GAC. The effect of the initial concentration of H2O2, the initial dye concentration, the initial catalyst concentration, the initial pH and temperature on the reaction rate constant were also studied. The activated energy for Fe-Mn/GAC catalyzed oxidation of the dye was determined to be 66.16KJ/mol. Reuse of catalyst did not decrease the removal rate of Orange IV. The tert-butanol experiment indicated that there were not only hydroxyl radicals but also other active species in the system.

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