EC 2.8.4.1     
Accepted name: coenzyme-B sulfoethylthiotransferase
Reaction: methyl-CoM + CoB = CoM-S-S-CoB + methane
Glossary: CoB = coenzyme B = N-(7-sulfanylheptanoyl)threonine = N-(7-mercaptoheptanoyl)threonine 3-O-phosphate (deprecated)
CoM = coenzyme M = 2-sulfanylethane-1-sulfonate = 2-mercaptoethanesulfonate (deprecated)
Other name(s): methyl-CoM reductase; methyl coenzyme M reductase
Systematic name: methyl-CoM:CoB S-(2-sulfoethyl)thiotransferase
Comments: This enzyme catalyses the final step in methanogenesis, the biological production of methane. This important anaerobic process is carried out only by methanogenic archaea. The enzyme can also function in reverse, for anaerobic oxidation of methane.The enzyme requires the hydroporphinoid nickel complex coenzyme F430. Highly specific for coenzyme B with a heptanoyl chain; ethyl CoM and difluoromethyl CoM are poor substrates. The sulfide sulfur can be replaced by selenium but not by oxygen.
References:
1.  Bobik, T.A., Olson, K.D., Noll, K.M. and Wolfe, R.S. Evidence that the heterodisulfide of coenzyme-M and 7-mercaptanoylthreonine phosphate is a product of the methylreductase reaction in Methanobacterium. Biochem. Biophys. Res. Commun. 149 (1987) 455–460. [PMID: 3122735]
2.  Ellermann, J., Hedderich, R., Boecher, R. and Thauer, R.K. The final step in methane formation: investigations with highly purified methyl coenzyme M reductase component C from Methanobacterium thermoautotrophicum (strain Marburg). Eur. J. Biochem. 184 (1988) 63–68.
3.  Ermler, U., Grabarse, W., Shima, S., Goubeaud, M. and Thauer, R.K. Crystal structure of methyl coenzyme M reductase: The key enzyme of biological methane formation. Science 278 (1997) 1457–1462. [PMID: 9367957]
4.  Signor, L., Knuppe, C., Hug, R., Schweizer, B., Pfaltz, A. and Jaun, B. Methane formation by reaction of a methyl thioether with a photo-excited nickel thiolate — a process mimicking methanogenesis in Archaea. Chemistry 6 (2000) 3508–3516. [PMID: 11072815]
5.  Scheller, S., Goenrich, M., Boecher, R., Thauer, R.K. and Jaun, B. The key nickel enzyme of methanogenesis catalyses the anaerobic oxidation of methane. Nature 465 (2010) 606–608. [PMID: 20520712]
[EC 2.8.4.1 created 2001, modified 2011]