Catalase-Like Activity of a Non-Heme Dibenzotetraaza[14]annulene−Fe(III) Complex under Physiological Conditions

The replacement of standard molecular mechanics force fields by inexpensive molecular orbital (QM') methods in multi-scale models has many advantages, e.g., a more straightforward description of mutual polarization and charge transfer between layers. The ONIOM(QM:QM') scheme with mechanical embedding can combine any two methods without prior parameterization or significant coding effort. In this scheme the environmental effect is evaluated fully at the QM' level and the accuracy therefore depends on how well the low-level QM' method describes the changes in electron density of the reacting region. To examine the applicability of the QM:QM' approach we perform case studies with density- Polarization effects are fairly well described using DFTB, but in some cases QM and QM' methods converge to different electronic states. We discuss when the QM:QM' approach is appropriate and the possibilities of estimating the quality of the ONIOM extension without having to make explicit benchmarks of the entire system. 3

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“…63 see Figure 6. The ONIOM model is formed by truncating the conjugated ligand at bonds that can formally be assigned as single bonds.…”

Section: Reaction Between Hydrogen Peroxide and A Non-heme Iron Camentioning

confidence: 99%

Case Studies of ONIOM(DFT:DFTB) and ONIOM(DFT:DFTB:MM) for Enzymes and Enzyme Mimics

Lundberg

Sasakura

Zheng

et al. 2010

J. Chem. Theory Comput.

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“…In recent years, we have been interested in the development of such catalase mimics based on macrocyclic non-heme Fe III complexes, and we presented 1 (Scheme 1), the first enzyme mimic of catalase which, as the tetrafluoroborate or chloride salt, acts under truly "physiological" conditions, that is, at ambient temperature and at low concentrations (micromolar) of H 2 O 2 and catalyst in aqueous solution at a pH of around 7. [29] Complex 1 decomposes hydrogen peroxide according to the catalase stoichiometry [Eq. (1)].…”

Section: Introductionmentioning

confidence: 99%

“…[60] Catalyst deactivation: The turnover numbers for H 2 O 2 decomposition by complex 1 and its analogues have been determined to be in the range of 40-80 mol H 2 O 2 per mole catalyst, that is, after these numbers of catalytic cycles the catalysts become deactivated. [29,30] In view of the high reactivity of the above-discussed intermediates, deactivation may reasonably be related to self-destruction of the complexes by oxidative attack on the [N 4 ] macrocyclic ligand, similar to the known oxidative degradation of iron porphyrins. [54,65] Fractional release of free HOC radicals (to give 1,3 9) may be a viable side reaction, although in reality HOC should be effectively trapped by the large excess of H 2 O 2 .…”

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confidence: 99%

Hydrogen Peroxide Decomposition by a Non‐Heme Iron(III) Catalase Mimic: A DFT Study

Sicking

Korth

Jansen

et al. 2007

Chemistry A European J

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Non-heme iron(III) complexes of 14-membered tetraaza macrocycles have previously been found to catalytically decompose hydrogen peroxide to water and molecular oxygen, like the native enzyme catalase. Here the mechanism of this reaction is theoretically investigated by DFT calculations at the (U)B3LYP/6-31G* level, with focus on the reactivity of the possible spin states of the FeIII complexes. The computations suggest that H2O2 decomposition follows a homolytic route with intermediate formation of an iron(IV) oxo radical cation species (L.+FeIV==O) that resembles Compound I of natural iron porphyrin systems. Along the whole catalytic cycle, no significant energetic differences were found for the reaction proceeding on the doublet (S=1/2) or on the quartet (S=3/2) hypersurface, with the single exception of the rate-determining O--O bond cleavage of the first associated hydrogen peroxide molecule, for which reaction via the doublet state is preferred. The sextet (S=5/2) state of the FeIII complexes appears to be unreactive in catalase-like reactions.

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“…For the detoxication of H 2 O 2 , and probably also for maintaining its regulatory function, nature has developed a family of highly eective enzymes, the catalases, which dismutate H 2 O 2 according to Eq. (1) [1,2]:…”

Section: Introductionmentioning

confidence: 99%

Efficiencies of the Copper(II) Adsorbed Zeolites in the H₂O₂Disproportionation Reaction

Çiçek

Dede

2014

Acta Phys. Pol. A

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This work describes FT-IR studies results on adsorption of Cu(II) metal cation. Adsorption has been performed on 3A, 4A, 5A, AW-300, ammonium Y zeolite, organophilic, and molecular sieve zeolites using aqueous solution of the metal studied. Changes in intensities and positions of the pseudolattice bands corresponding to ring vibrations have been observed in the measured spectra. These changes are expected particularly in the pseudolattice bands connected with the presence of alumino-and silicooxygen tetrahedral rings in the zeolite structure. Also, Cu(II) adsorbed zeolites were each tested for their ability to catalyse the disproportionation of hydrogen peroxide in the presence of the added base imidazole. The Cu(II) adsorbed zeolites display eciency in the disproportion reactions of hydrogen peroxide, producing water and dioxygen.

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Catalase-Like Activity of a Non-Heme Dibenzotetraaza[14]annulene−Fe(III) Complex under Physiological Conditions

Cited by 46 publications

References 20 publications

Case Studies of ONIOM(DFT:DFTB) and ONIOM(DFT:DFTB:MM) for Enzymes and Enzyme Mimics

Case Studies of ONIOM(DFT:DFTB) and ONIOM(DFT:DFTB:MM) for Enzymes and Enzyme Mimics

Hydrogen Peroxide Decomposition by a Non‐Heme Iron(III) Catalase Mimic: A DFT Study

Efficiencies of the Copper(II) Adsorbed Zeolites in the H₂O₂Disproportionation Reaction

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Catalase-Like Activity of a Non-Heme Dibenzotetraaza[14]annulene−Fe(III) Complex under Physiological Conditions

Cited by 46 publications

References 20 publications

Case Studies of ONIOM(DFT:DFTB) and ONIOM(DFT:DFTB:MM) for Enzymes and Enzyme Mimics

Case Studies of ONIOM(DFT:DFTB) and ONIOM(DFT:DFTB:MM) for Enzymes and Enzyme Mimics

Hydrogen Peroxide Decomposition by a Non‐Heme Iron(III) Catalase Mimic: A DFT Study

Efficiencies of the Copper(II) Adsorbed Zeolites in the H2O2Disproportionation Reaction

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Product

Resources

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Efficiencies of the Copper(II) Adsorbed Zeolites in the H₂O₂Disproportionation Reaction