Publication Details

Category Text Publication
Reference Category Journals
DOI 10.1021/acs.est.7b04278
Document accepted manuscript
Title (Primary) Interaction mode and regioselectivity in vitamin B12-dependent dehalogenation of aryl halides by Dehalococcoides mccartyi strain CBDB1
Author Zhang, S.; Adrian, L.; Schüürmann, G.
Source Titel Environmental Science & Technology
Year 2018
Department ISOBIO; OEC
Volume 52
Issue 4
Page From 1834
Page To 1843
Language englisch
Supplements https://pubs.acs.org/doi/suppl/10.1021/acs.est.7b04278
UFZ wide themes RU3;
Abstract The bacterium Dehalococcoides, strain CBDB1, transforms aromatic halides through reductive dehalogenation. So far, however, the structures of its vitamin B12-containing dehalogenases are unknown, hampering clarification of the catalytic mechanism and substrate specificity as basis for targeted remediation strategies. This study employs a quantum chemical donor–acceptor approach for the Co(I)-substrate electron transfer. Computational characterization of the substrate electron affinity at carbon–halogen bonds enables discriminating aromatic halides ready for dehalogenation by strain CBDB1 (active substrates) from nondehalogenated (inactive) counterparts with 92% accuracy, covering 86 of 93 bromobenzenes, chlorobenzenes, chlorophenols, chloroanilines, polychlorinated biphenyls, and dibenzo-p-dioxins. Moreover, experimental regioselectivity is predicted with 78% accuracy by a site-specific parameter encoding the overlap potential between the Co(I) HOMO (highest occupied molecular orbital) and the lowest-energy unoccupied sigma-symmetry substrate MO (σ*), and the observed dehalogenation pathways are rationalized with a success rate of 81%. Molecular orbital analysis reveals that the most reactive unoccupied sigma-symmetry orbital of carbon-attached halogen X (σC–X*) mediates its reductive cleavage. The discussion includes predictions for untested substrates, thus providing opportunities for targeted experimental investigations. Overall, the presently introduced orbital interaction model supports the view that with bacterial strain CBDB1, an inner-sphere electron transfer from the supernucleophile B12 Co(I) to the halogen substituent of the aromatic halide is likely to represent the rate-determining step of the reductive dehalogenation.
Persistent UFZ Identifier https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=20076
Zhang, S., Adrian, L., Schüürmann, G. (2018):
Interaction mode and regioselectivity in vitamin B12-dependent dehalogenation of aryl halides by Dehalococcoides mccartyi strain CBDB1
Environ. Sci. Technol. 52 (4), 1834 - 1843 10.1021/acs.est.7b04278