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Mumbo, J. ; Lenoir, D. ; Henkelmann, B. ; Schramm, K.-W.

Enzymatic synthesis of bromo- and chlorocarbazoles and elucidation of their structures by molecular modeling.

Environ. Sci. Pollut. Res. 20, 8996-9005 (2013)
DOI PMC
Open Access Green möglich sobald Postprint bei der ZB eingereicht worden ist.
3-Chlorocarbazole, 3,6-dichlorocarbazole, dibromocarbazole, and 1,3,6,8-tetrabromocarbazole are emerging environmental contaminants which have been detected recently in water, sediment, and soil samples. However, their sources and occurrence have not been explained. Here, we report an enzymatic synthesis of bromo- and chlorocarbazoles by chloroperoxidase from Caldariomyces fumago in water. Density functional theory (DFT) method was used to predict the most stable products. Carbazole and chloroperoxidase were assayed in vitro in the presence of hydrogen peroxide, bromide, and chloride ions in different substrate ratio treatments against constant and varying enzyme concentrations. Halogenated carbazoles formed were identified by high-resolution gas chromatography coupled to mass spectrometry. In all treatments, bromination and chlorination took place, but the composition and concentration of compounds formed varied from one treatment to another. Mono-, di-, tri-, and tetra-substituted bromo- and chlorocarbazoles which include the reported environmental contaminants were synthesized. 3-Substituted and 3,6-substituted congeners were relatively higher in concentration. Enzyme concentration did not favor preferential formation of any of the compounds synthesized. However, their synthesis was influenced by halide concentration. Congeners with bromine and chlorine at position of C-3, C-3,6, C-1,3,6, and C-1,3,6,8 were calculated as the stable intermediate sigma complexes by DFT method. Regioselectivity in halogenation is discussed and hypothesis of the likely stable products in the environment explained. This study provides evidence that bromo- and chlorocarbazoles reported previously can be formed enzymatically in the environment, demonstrating the need to consider aromatic pollutants transformation and their potential toxicity enhancements in the management of water pollution and contaminated sites.
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Publikationstyp Artikel: Journalartikel
Dokumenttyp Wissenschaftlicher Artikel
Schlagwörter Bromocarbazoles; Chlorocarbazoles; Chloroperoxidase; Density functional theory (DFT) calculations; Enzymatic bromination and chlorination; Regioselectivity in halogenation; Aromatic-hydrocarbons ; Hydrogen-peroxide ; Chloroperoxidase ; Chlorination ; Carbazole ; Haloperoxidases ; Identification ; Biosynthesis ; Halogenation ; Water
ISSN (print) / ISBN 0944-1344
e-ISSN 1614-7499
Zeitschrift Environmental Science and Pollution Research
Quellenangaben Band: 20, Heft: 12, Seiten: 8996-9005 Artikelnummer: , Supplement: ,
Verlag Springer
Begutachtungsstatus Peer reviewed
Institut(e) PPM-MEX-Molecular EXposomics (MEX)