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Mechanism of Selective Halogenation by SyrB2: A Computational Study
Stockholm University, Faculty of Science, Department of Physics.
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2010 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 132, no 37, 12887-12898 p.Article in journal (Refereed) Published
Abstract [en]

The mechanism of the chlorination reaction of SyrB2, a representative α-ketoglutarate dependent halogenase, was studied with computational methods. First, a macromolecular model of the Michaelis com- plex was constructed using molecular docking proce- dures. Based on this structure a smaller model com- prising the first- and some of the second shell residues of iron, and a model substrate was constructed and used in DFT investigations on the reaction mecha- nism. Computed relative energies and Mo ̈ssbauer iso- mer shifts and quadrupole splittings indicate that the two oxoferryl species observed experimentally are two stereoisomers resulting from an exchange of the coordi- nation sites occupied by the oxo and chloro ligands. In principle both FeIV =O species are reactive and decay to FeIIICl(OH)/carbon radical intermediates via C-H bond cleavage. In the final rebound step, which is very fast and thus precluding equilibration between the two forms of the radical intermediate, the ligand (oxo or chloro) placed closest to the carbon radical (trans to His235) is transfered to the carbon. For the native substrate (L-Thr) the lowest barrier for C-H cleavage was found for an isomer of the oxoferryl species favor- ing chlorination in the rebound step. CASPT2 cal- culations for the spin state splittings in the oxoferryl species support the conclusion that once the FeIV =O intermediate is formed, the reaction proceeds on the quintet potential energy surface.

Place, publisher, year, edition, pages
2010. Vol. 132, no 37, 12887-12898 p.
National Category
Inorganic Chemistry
Research subject
Physical Chemistry
URN: urn:nbn:se:su:diva-38193DOI: 10.1021/ja101877aISI: 000282013700040OAI: diva2:306940
Available from: 2010-03-31 Created: 2010-03-31 Last updated: 2011-11-24Bibliographically approved
In thesis
1. Biomimetic Iron Complexes involved in Oxygenation and Chlorination: A Theoretical Study
Open this publication in new window or tab >>Biomimetic Iron Complexes involved in Oxygenation and Chlorination: A Theoretical Study
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Biomimetic chemistry is directed towards the simulation of enzymatic reactivity with synthetic analogues. In this thesis a quantum chemical method has been employed to study the mechanism of highly reactive iron-oxo complexes involved in oxygenation and chlorination of organic substrates. The aim of this research is to gain greater understanding for the reactivity paradigm of the iron-oxo group.

One reaction deals with the conversion of cyclohexane into adipic acid, a key chemical in industrial chemistry, catalyzed by an iron(II)-porphyrin complex in the presence of dioxygen. This process constitutes a ’green’ alternative to conventional adipic acid production, and is thus of great interest to synthetic chemistry. Another reaction investigated herein regards the selective chlorination observed for a new group of non-heme iron enzymes. With help of theoretical modeling it was possible to propose a mechanism that explains the observed selectivity. It is furthermore demonstrated how a biomimetic iron complex simulates the enzymatic reactivity by a different mechanism.

Other topics covered in this thesis regard the structure-reactivity relationship of a binuclear iron complex and the intradiol C-C bond cleavage of catechol catalyzed by an iron(III) complex.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University, 2010. a-d, viii, 75 p.
biomimetic, iron, density functional theory, intradiol, chlorination, adpic acid, diamond core, reactivity
National Category
Inorganic Chemistry Theoretical Chemistry
Research subject
Chemical Physics
urn:nbn:se:su:diva-38197 (URN)978–91–7447–013–0 (ISBN)
Public defence
2010-04-30, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 10:00 (English)
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Submitted. Paper 2: Accepted. Paper 3: Submitted.Available from: 2010-04-08 Created: 2010-03-31 Last updated: 2010-04-07Bibliographically approved

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Noack, HolgerSiegbahn, Per E.M.
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