Publication Details |
Category | Text Publication |
Reference Category | Journals |
DOI | 10.1021/acs.est.3c00364 |
Title (Primary) | Insight into the mechanism underlying Dehalococcoides mccartyi strain CBDB1-mediated B12-dependent aromatic reductive dehalogenation |
Author | Zhang, S.; Wen, W.; Xia, X.; Ouyang, W.; Mai, B.-X.; Adrian, L.; Schüürmann, G. |
Source Titel | Environmental Science & Technology |
Year | 2023 |
Department | OEC; UBT |
Volume | 57 |
Issue | 29 |
Page From | 10773 |
Page To | 10781 |
Language | englisch |
Topic | T7 Bioeconomy |
Supplements | https://pubs.acs.org/doi/suppl/10.1021/acs.est.3c00364/suppl_file/es3c00364_si_001.pdf |
Keywords | Dehalococcoides; reductive dehalogenation; aromatic halide; thermodynamics; reaction mechanism |
Abstract | Anaerobic bacteria transform aromatic halides through reductive dehalogenation. This dehalorespiration is catalyzed by the supernucleophilic coenzyme vitamin B12, cob(I)alamin, in reductive dehalogenases. So far, the underlying inner-sphere electron transfer (ET) mechanism has been discussed controversially. In the present study, all 36 chloro-, bromo-, and fluorobenzenes and full-size cobalamin are analyzed at the quantum chemical density functional theory level with respect to a wide range of theoretically possible inner-sphere ET mechanisms. The calculated reaction free energies within the framework of CoI···X (X = F, Cl, and Br) attack rule out most of the inner-sphere pathways. The only route with feasible energetics is a proton-coupled two-ET mechanism that involves a B12 side-chain tyrosine (modeled by phenol) as a proton donor. For 12 chlorobenzenes and 9 bromobenzenes with experimental data from Dehalococcoides mccartyi strain CBDB1, the newly proposed PC-TET mechanism successfully discriminates 16 of 17 active from 4 inactive substrates and correctly predicts the observed regiospecificity to 100%. Moreover, fluorobenzenes are predicted to be recalcitrant in agreement with experimental findings. Conceptually, based on the Bell–Evans–Polanyi principle, the computational approach provides novel mechanistic insights and may serve as a tool for predicting the energetic feasibility of reductive aromatic dehalogenation. |
Persistent UFZ Identifier | https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=27397 |
Zhang, S., Wen, W., Xia, X., Ouyang, W., Mai, B.-X., Adrian, L., Schüürmann, G. (2023): Insight into the mechanism underlying Dehalococcoides mccartyi strain CBDB1-mediated B12-dependent aromatic reductive dehalogenation Environ. Sci. Technol. 57 (29), 10773 - 10781 10.1021/acs.est.3c00364 |