An investigation of possible competing mechanisms for Ni-containing methyl–coenzyme M reductase (original) (raw)
* Corresponding authors
a Key Laboratory of Cluster Science of Ministry of Education, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry, Beijing Institute of Technology, Beijing 100081, China
E-mail: shlchen@bit.edu.cn
Tel: +86-10-68918670
b Department of Organic Chemistry, Stockholm University, SE-10691 Stockholm, Sweden
E-mail: ps@organ.su.se
Fax: +46-8-153679
Abstract
Ni-containing methyl–coenzyme M reductase (MCR) is capable of catalyzing methane formation from methyl–coenzyme M (CH3–SCoM) and coenzyme B (CoB–SH), and also its reverse reaction (methane oxidation). Based on extensive experimental and theoretical investigations, it has turned out that a mechanism including an organometallic methyl–Ni(III)F430 intermediate is inaccessible, while another mechanism involving a methyl radical and a Ni(II)–SCoM species currently appears to be the most acceptable one for MCR. In the present paper, using hybrid density functional theory and an active-site model based on the X-ray crystal structure, two other mechanisms were studied and finally also ruled out. One of them, involving proton binding on the CH3–SCoM substrate, which should facilitate methyl–Ni(III)F430 formation, is demonstrated to be quite unfavorable since the substrate has a much smaller proton affinity than the F430 cofactor. Another one (oxidative addition mechanism) is also shown to be unfavorable for the MCR reaction, due to the large endothermicity for the formation of the ternary intermediate with side-on C–S (for CH3–SCoM) or C–H (for methane) coordination to Ni.
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Article information
DOI
https://doi.org/10.1039/C4CP01483A
Article type
Paper
Submitted
05 Apr 2014
Accepted
19 May 2014
First published
19 May 2014
Download Citation
Phys. Chem. Chem. Phys., 2014,16, 14029-14035
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An investigation of possible competing mechanisms for Ni-containing methyl–coenzyme M reductase
S. Chen, M. R. A. Blomberg and P. E. M. Siegbahn,Phys. Chem. Chem. Phys., 2014, 16, 14029DOI: 10.1039/C4CP01483A
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