A Mechanism for Oxygen Exchange between Ligated Oxometalloporphinates and Bulk Water

Primus, Jean-Louis; Teunis, Kees; Mandon, Dominique; Veeger, C.; Rietjens, Ivonne M. C. M.

doi:10.1006/bbrc.2000.2809

Cited by 11 publications

(4 citation statements)

References 30 publications

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“…H 2 18 O is commonly used to test the involvement of accumulated FeO species in cytochrome P450 model reactions because it exchanges with FeO via a tautomeric mechanism (Scheme ) . Accumulated FeO species are therefore expected to undergo 18 O exchange and incorporate the labeled isotope into the products.…”

Section: Discussionmentioning

confidence: 99%

Concerted Dismutation of Chlorite Ion: Water-Soluble Iron-Porphyrins As First Generation Model Complexes for Chlorite Dismutase

Zdilla¹,

Lee²,

Abu‐Omar³

2009

Inorg. Chem.

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Three iron-5,10,15,20-tetraarylporphyrins (Fe(Por-Ar4), Ar = 2,3,5,6-tetrafluro-N,N,N-trimethylanilinium (1), N,N,N-trimethylanilinium (2), and p-sulfonatophenyl (3)) have been investigated as catalysts for the dismutation of chlorite (ClO2-). Degradation of ClO2- by these catalysts occurs by two concurrent pathways. One leads to formation of chlorate (ClO3-) and chloride (Cl-), which is determined to be catalyzed by O=FeIV(Por) (Compound II) based on stopped-flow absorption spectroscopy, competition with 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonicacid), 18O-labeling studies, and kinetics. The second pathway is a concerted dismutation of chlorite to dioxygen (O2) and chloride. On the basis of isotope labeling studies using a residual gas analyzer, the mechanism is determined to be formation of O=FeIV(Por)*+ (Compound I) from oxygen atom transfer, and subsequent rebound with the resulting hypochlorite ion (ClO-) to give dioxygen and chloride. While the chlorate production pathway is dominant for catalysts 2 and 3, the O2-producing pathway is significant for catalyst 1. In addition to chlorite dismutation, complex 1 catalyzes hypochlorite disproportionation to chloride and dioxygen quantitatively.

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Section: Discussionmentioning

confidence: 99%

Concerted Dismutation of Chlorite Ion: Water-Soluble Iron-Porphyrins As First Generation Model Complexes for Chlorite Dismutase

Zdilla¹,

Lee²,

Abu‐Omar³

2009

Inorg. Chem.

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“…This 896 Da (ϩ16 Da) Fig. 4 identified the 781-Da (ϩ30 Da) fragment as modified WDRFK (43)(44)(45)(46)(47) and the 896-Da (ϩ16 Da) fragment as EKWDRF (41)(42)(43)(44)(45)(46). A number of product ions were detected by MALDI-TOF MS/MS for the 781-and 896-Da peaks using post-source decay, which could be assigned to the b and y ion systems (predicted by Sherpa lite 4.0.)…”

Section: Uv-visible Spectroscopy Of Mb Wdi-mentioning

confidence: 92%

Monooxygenation of an Aromatic Ring by F43W/H64D/V68I Myoglobin Mutant and Hydrogen Peroxide

Pfister¹,

Ohki²,

Ueno³

et al. 2005

Journal of Biological Chemistry

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Myoglobin (Mb)1 is a small (17 kDa), well characterized heme protein that is often used as a model system for other heme proteins and the reactions they catalyze. In addition to its native function as an oxygen carrier, Mb has been engineered to efficiently perform peroxidase, catalase, and peroxygenase (sulfoxidation and epoxidation) activities (1-4). Scheme 1 shows three major alternate pathways for the reaction with peroxide. The latest novel function to be proposed for Mb is cytochrome P450-type aromatic carbon hydroxylation. Although hydroxylation by P450s has been extensively studied (5-7), the mechanism is still not fully understood (6,8). Input from new model systems could provide additional insight. P450 enzymes capture their substrates near the heme via specific interactions (9 -11), which Mb cannot do. A Trp was, thus, engineered in the heme pocket of Mb to model P450 hydroxylation of aromatic compounds ( Fig. 1) (12, 13). The monooxygenation product has not previously been observed or isolated due to rapid subsequent oxidation steps.The mechanism of hydroxylation by P450s is proving to be quite complex and may even vary among various P450s (7). Some of the proposed mechanisms involve 1) an epoxide intermediate for the aromatic hydroxylation, 2) a concerted direct insertion of oxygen, 3) a non-concerted sequential insertion involving hydrogen abstraction and oxygen rebound, or 4) a more simple non-concerted radical mechanism (6 -8, 14). Recently it has been found that these mechanisms may not be entirely valid, and the actual mechanism may involve two electrophilic oxidants and/or two spin states of the iron oxo species (6,8,14). Although P450cam has been shown to lose its hydroxylation activity when an imidizole is substituted for the axial thiolate ligand (15, 16), in contrast, chloroperoxidase retains its chlorination, peroxidation, epoxidation, and catalase activities when its thiolate ligand is mutated to histidine (17). Also, studies with iron porphyrin compounds have demonstrated that imidazole ligation can replace the thiolate in P450 type reactions under certain conditions (18). Therefore, because * This work was supported by Grants-in-Aid for Scientific Research 14209019 (to Y. W). and 13740384 (to T. U.) and by the 21st Century COE program "Establishment of COE on Materials Science: Elucidation and Creation of Molecular Functions" of Nagoya University (to T. D. P.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. ** Present address: National Institute of Advanced Industrial Science and Technology Research Institute of Genome-based Biofactory, 2-17 Tsukisamu-Higashi, Toyohira, Sapporo 062-8517, Japan.ʈʈ To whom correspondence should be addressed. Tel.: 81-52-789-3049; Fax: 81-52-789-2953; E-mail: yoshi@nucc.cc.nagoya-u.ac.jp. 1 The abbreviations used are: Mb, myoglobin; Mb WDI, Mb F43W/ H64D/V68I mutant; Mb WL, Mb ...

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“…It remains to be explained how, if the Ni-A and Ni-SU states are Ni(III)−OOH - /Cys−S - and Ni(II)−OOH - /Cys−S - , respectively, an oxygen atom from either H 2 17 O or 17 O 2 can be found in the peroxo ligand. , A possibility is provided by the following reaction, analogous to the reported exchange reaction of peroxide with water in the model heme catalyst, microperoxidase-8: …”

Section: 1 Oxidized Inactive States Of the Ni−fe Site And Radiation E...mentioning

confidence: 99%

Structure/Function Relationships of [NiFe]- and [FeFe]-Hydrogenases

et al. 2007

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4286 6.1. Oxidized Inactive States of the Ni−Fe Site and Radiation Effects 4286 6.2. Oxidative Damage of FeS Clusters in [FeFe]-Hydrogenases 4288 6.3. Hydrophobic Tunnels in [NiFe]-Hydrogenases 4288 6.4. Hydrophobic Tunnels in [FeFe]-Hydrogenase 4291 6.5. Hydrogen Sensors Related to [NiFe]-Hydrogenases 4292 6.6. Oxygen-Insensitive [NiFe]-Hydrogenases from Ralstonia eutropha 4294 7. Evolutionary Relationships of Hydrogenases to Other Proteins 4294 7.1. Comparison of [NiFe]-Hydrogenase with Complex I 4294 7.2. Comparison of [FeFe]-Hydrogenase to Narf-like Proteins 4296 8. Substrate Binding and Catalysis 4297 8.1. [NiFe]-Hydrogenases 4297 8.2. [FeFe]-Hydrogenases 4297 8.3. Comparison of Active Redox States in [NiFe]and [FeFe]-Hydrogenases 4299 9. Concluding Remarks 4299 10. Acknowledgments 4300 11. Note Added after ASAP Publication 4300 12. References 4300

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A Mechanism for Oxygen Exchange between Ligated Oxometalloporphinates and Bulk Water

Cited by 11 publications

References 30 publications

Concerted Dismutation of Chlorite Ion: Water-Soluble Iron-Porphyrins As First Generation Model Complexes for Chlorite Dismutase

Concerted Dismutation of Chlorite Ion: Water-Soluble Iron-Porphyrins As First Generation Model Complexes for Chlorite Dismutase

Monooxygenation of an Aromatic Ring by F43W/H64D/V68I Myoglobin Mutant and Hydrogen Peroxide

Structure/Function Relationships of [NiFe]- and [FeFe]-Hydrogenases

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