Coenzyme M

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Coenzyme M is a coenzyme required for methyl-transfer reactions in the metabolism of methanogens.[1][2] The coenzyme is an anion with the formula HSCH2CH2SO3-. It is named 2-mercaptoethanesulfonate and abbreviated HS-CoM. The cation is unimportant, but the sodium salt is most available. Mercaptoethanesulfonate contains both a thiol, which is the main site of reactivity, and a sulfonate group, which confers solubility in aqueous media.

Biochemical role

The coenzyme is the C1 carrier in methanogenesis. It is converted to methyl coenzyme M, the thioether CH3SCH2CH2SO3-, in the penultimate step to methane formation.[3] Coenzyme M reacts with coenzyme B, 7-thioheptanoylthreoninephosphate, to give a heterodisulfide, releasing methane:

CH3-S-CoM + HS-CoB → CH4 + CoB-S-S-CoM

This conversion is catalyzed by the enzyme methyl coenzyme M reductase, which contains cofactor F430 as the prosthetic group.


  1. Balch WE, Wolfe RS (1979). "Specificity and biological distribution of coenzyme M (2-mercaptoethanesulfonic acid)". J. Bacteriol. 137 (1): 256–63. PMID 104960.
  2. Taylor CD, Wolfe RS (1974). "Structure and methylation of coenzyme M(HSCH2CH2SO3)". J. Biol. Chem. 249 (15): 4879–85. PMID 4367810.
  3. Thauer, R. K., "Biochemistry of Methanogenesis: a Tribute to Marjory Stephenson", Microbiology, 1998, volume 144, pages 2377-2406.