PMID:17902704
| Citation |
Dey, M, Kunz, RC, Lyons, DM and Ragsdale, SW (2007) Characterization of alkyl-nickel adducts generated by reaction of methyl-coenzyme m reductase with brominated acids. Biochemistry 46:11969-78 |
|---|---|
| Abstract |
Methyl-coenzyme M reductase (MCR) from methanogenic archaea catalyzes the final step in the biological synthesis of methane. Using coenzyme B (CoBSH) as the two-electron donor, MCR reduces methyl-coenzyme M (methyl-SCoM) to methane and the mixed disulfide, CoB-S-S-CoM. MCR contains coenzyme F430, an essential redox-active nickel tetrahydrocorphin, at its active site. The active form of MCR (MCRred1) contains Ni(I)-F430. When 3-bromopropane sulfonate (BPS) is incubated with MCRred1, an alkyl-Ni(III) species is formed that elicits the MCRPS EPR signal. Here we used EPR and UV-visible spectroscopy and transient kinetics to study the reaction between MCR from Methanothermobacter marburgensis and a series of brominated carboxylic acids, with carbon chain lengths of 4-16. All of these compounds give rise to an alkyl-Ni intermediate with an EPR signal similar to that of the MCRPS species. Reaction of the alkyl-Ni(III) adduct, formed from brominated acids with eight or fewer total carbons, with HSCoM as nucleophile at pH 10.0 results in the formation of a thioether coupled to regeneration of the active MCRred1 state. When reacted with 4-bromobutyrate, MCRred1 forms the alkyl-Ni(III) MCRXA state and then, surprisingly, undergoes "self-reactivation" to regenerate the Ni(I) MCRred1 state and a bromocarboxy ester. The results demonstrate an unexpected reactivity and flexibility of the MCR active site in accommodating a broad range of substrates, which act as molecular rulers for the substrate channel in MCR. |
| Links |
PubMed PMC3553217 Online version:10.1021/bi700925n |
| Keywords |
Alkanesulfonic Acids/chemistry; Alkanesulfonic Acids/metabolism; Binding Sites; Carboxylic Acids/chemistry; Carboxylic Acids/metabolism; Electron Spin Resonance Spectroscopy; Kinetics; Methanobacteriaceae/enzymology; Models, Chemical; Molecular Structure; Nickel/chemistry; Nickel/metabolism; Oxidoreductases/chemistry; Oxidoreductases/isolation & purification; Oxidoreductases/metabolism; Protein Binding; Spectrophotometry, Ultraviolet |
| edit table |
Significance
You can help EcoliWiki by summarizing why this paper is useful
Useful Materials and Methods
You can help Ecoliwiki by describing the useful materials (strains, plasmids, antibodies, etc) described in this paper.
Annotations
<annotationlinks/>
EcoliWiki Links
Add links to pages that link here (e.g. gene, product, method pages)
References
See Help:References for how to manage references in EcoliWiki.