Publication Date:
2010-06-04
Description:
Large amounts (estimates range from 70 Tg per year to 300 Tg per year) of the potent greenhouse gas methane are oxidized to carbon dioxide in marine sediments by communities of methanotrophic archaea and sulphate-reducing bacteria, and thus are prevented from escaping into the atmosphere. Indirect evidence indicates that the anaerobic oxidation of methane might proceed as the reverse of archaeal methanogenesis from carbon dioxide with the nickel-containing methyl-coenzyme M reductase (MCR) as the methane-activating enzyme. However, experiments showing that MCR can catalyse the endergonic back reaction have been lacking. Here we report that purified MCR from Methanothermobacter marburgensis converts methane into methyl-coenzyme M under equilibrium conditions with apparent V(max) (maximum rate) and K(m) (Michaelis constant) values consistent with the observed in vivo kinetics of the anaerobic oxidation of methane with sulphate. This result supports the hypothesis of 'reverse methanogenesis' and is paramount to understanding the still-unknown mechanism of the last step of methanogenesis. The ability of MCR to cleave the particularly strong C-H bond of methane without the involvement of highly reactive oxygen-derived intermediates is directly relevant to catalytic C-H activation, currently an area of great interest in chemistry.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Scheller, Silvan -- Goenrich, Meike -- Boecher, Reinhard -- Thauer, Rudolf K -- Jaun, Bernhard -- England -- Nature. 2010 Jun 3;465(7298):606-8. doi: 10.1038/nature09015.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Organic Chemistry, ETH Zurich, Wolfgang-Pauli-Str. 10, 8093 Zurich, Switzerland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20520712" target="_blank"〉PubMed〈/a〉
Keywords:
Anaerobiosis
;
*Biocatalysis
;
Gases/metabolism
;
Kinetics
;
Mesna/analogs & derivatives/metabolism
;
Methane/*biosynthesis/*metabolism
;
Methanobacteriaceae/*enzymology
;
Methylation
;
Models, Biological
;
Nickel/*metabolism
;
Oxidation-Reduction
;
Oxidoreductases/*metabolism
;
Temperature
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
