The Enzyme Database

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EC 1.1.1.268     
Accepted name: 2-(R)-hydroxypropyl-CoM dehydrogenase
Reaction: 2-(R)-hydroxypropyl-CoM + NAD+ = 2-oxopropyl-CoM + NADH + H+
For diagram of epoxide carboxylation, click here
Glossary: coenzyme M (CoM) = 2-mercaptoethanesulfonate
Other name(s): 2-(2-(R)-hydroxypropylthio)ethanesulfonate dehydrogenase
Systematic name: 2-[2-(R)-hydroxypropylthio]ethanesulfonate:NAD+ oxidoreductase
Comments: The enzyme is highly specific for (R)-2-hydroxyalkyl thioethers of CoM, in contrast to EC 1.1.1.269, 2-(S)-hydroxypropyl-CoM dehydrogenase, which is highly specific for the (S)-enantiomer. This enzyme forms component III of a four-component enzyme system {comprising EC 4.4.1.23 (2-hydroxypropyl-CoM lyase; component I), EC 1.8.1.5 [2-oxopropyl-CoM reductase (carboxylating); component II], EC 1.1.1.268 [2-(R)-hydroxypropyl-CoM dehydrogenase; component III] and EC 1.1.1.269 [2-(S)-hydroxypropyl-CoM dehydrogenase; component IV]} that is involved in epoxyalkane carboxylation in Xanthobacter sp. strain Py2.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, UM-BBD, CAS registry number: 244301-33-5
References:
1.  Allen, J.R., Clark, D.D., Krum, J.G. and Ensign, S.A. A role for coenzyme M (2-mercaptoethanesulfonic acid) in a bacterial pathway of aliphatic epoxide carboxylation. Proc. Natl. Acad. Sci. USA 96 (1999) 8432–8437. [DOI] [PMID: 10411892]
[EC 1.1.1.268 created 2001]
 
 
EC 1.1.1.269     
Accepted name: 2-(S)-hydroxypropyl-CoM dehydrogenase
Reaction: (2S)-2-hydroxypropyl-CoM + NAD+ = 2-oxopropyl-CoM + NADH + H+
For diagram of epoxide carboxylation, click here
Glossary: coenzyme M (CoM) = 2-mercaptoethanesulfonate
Other name(s): 2-(2-(S)-hydroxypropylthio)ethanesulfonate dehydrogenase; 2-[2-(S)-hydroxypropylthio]ethanesulfonate:NAD+ oxidoreductase
Systematic name: 2-{[(2S)-2-hydroxypropyl]sulfanyl}ethanesulfonate:NAD+ oxidoreductase
Comments: The enzyme is highly specific for (2S)-2-hydroxyalkyl thioethers of CoM, in contrast to EC 1.1.1.268, 2-(R)-hydroxypropyl-CoM dehydrogenase, which is highly specific for the (R)-enantiomer. This enzyme forms component IV of a four-component enzyme system EC 4.4.1.23 (2-hydroxypropyl-CoM lyase; component I), EC 1.8.1.5 [2-oxopropyl-CoM reductase (carboxylating); component II], EC 1.1.1.268 [2-(R)-hydroxypropyl-CoM dehydrogenase; component III] and EC 1.1.1.269 [2-(S)-hydroxypropyl-CoM dehydrogenase; component IV].html">click here that is involved in epoxyalkane carboxylation in Xanthobacter sp. strain Py2.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, UM-BBD, CAS registry number: 369364-40-9
References:
1.  Allen, J.R., Clark, D.D., Krum, J.G. and Ensign, S.A. A role for coenzyme M (2-mercaptoethanesulfonic acid) in a bacterial pathway of aliphatic epoxide carboxylation. Proc. Natl. Acad. Sci. USA 96 (1999) 8432–8437. [DOI] [PMID: 10411892]
[EC 1.1.1.269 created 2001]
 
 
EC 1.1.1.272     
Accepted name: D-2-hydroxyacid dehydrogenase (NADP+)
Reaction: an (R)-2-hydroxycarboxylate + NADP+ = a 2-oxocarboxylate + NADPH + H+
For diagram of coenzyme M biosynthesis, click here
Other name(s): ddh (gene name)
Systematic name: (R)-2-hydroxycarboxylate:NADP+ oxidoreductase
Comments: This enzyme, characterized from the halophilic archaeon Haloferax mediterranei and the mold Aspergillus oryzae, catalyses a stereospecific reduction of 2-oxocarboxylic acids into the corresponding D-2-hydroxycarboxylic acids. The enzyme prefers substrates with a main chain of 5 carbons (such as 4-methyl-2-oxopentanoate) to those with a shorter chain, and can use NADH with much lower efficiency. cf. EC 1.1.1.345, (D)-2-hydroxyacid dehydrogenase (NAD+).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 81210-65-3
References:
1.  Domenech, J. and Ferrer, J. A new D-2-hydroxyacid dehydrogenase with dual coenzyme-specificity from Haloferax mediterranei, sequence analysis and heterologous overexpression. Biochim. Biophys. Acta 1760 (2006) 1667–1674. [DOI] [PMID: 17049749]
2.  Shimizu, M., Yamamoto, T., Okabe, N., Sakai, K., Koide, E., Miyachi, Y., Kurimoto, M., Mochizuki, M., Yoshino-Yasuda, S., Mitsui, S., Ito, A., Murano, H., Takaya, N. and Kato, M. Novel 4-methyl-2-oxopentanoate reductase involved in synthesis of the Japanese sake flavor, ethyl leucate. Appl. Microbiol. Biotechnol. (2015) . [DOI] [PMID: 26615399]
[EC 1.1.1.272 created 2002, modified 2013]
 
 
EC 1.1.1.338     
Accepted name: (2R)-3-sulfolactate dehydrogenase (NADP+)
Reaction: (2R)-3-sulfolactate + NADP+ = 3-sulfopyruvate + NADPH + H+
For diagram of coenzyme-M biosynthesis, click here
Other name(s): (R)-sulfolactate:NADP+ oxidoreductase; L-sulfolactate dehydrogenase; (R)-sulfolactate dehydrogenase; ComC
Systematic name: (2R)-3-sulfolactate:NADP+ oxidoreductase
Comments: The enzyme from the bacterium Chromohalobacter salexigens can only utilize NADP+. It functions both biosynthetically in coenzyme M biosynthesis and degradatively, in the degradation of sulfolactate. It can not use (S)-malate and (S)-lactate.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 81210-65-3
References:
1.  Denger, K. and Cook, A.M. Racemase activity effected by two dehydrogenases in sulfolactate degradation by Chromohalobacter salexigens: purification of (S)-sulfolactate dehydrogenase. Microbiology 156 (2010) 967–974. [DOI] [PMID: 20007648]
[EC 1.1.1.338 created 2012]
 
 
EC 1.2.7.12     
Accepted name: formylmethanofuran dehydrogenase
Reaction: a formylmethanofuran + H2O + 2 oxidized ferredoxin [iron-sulfur] cluster = CO2 + a methanofuran + 2 reduced ferredoxin [iron-sulfur] cluster + 2 H+
For diagram of methane biosynthesis, click here
Glossary: methanofuran a = 4-[4-(2-{[(4R*,5S*)-4,5,7-tricarboxyheptanoyl]-γ-L-glutamyl-γ-L-glutamylamino}ethyl)phenoxymethyl]furan-2-ylmethanamine
Other name(s): formylmethanofuran:acceptor oxidoreductase
Systematic name: formylmethanofuran:ferredoxin oxidoreductase
Comments: Contains a molybdopterin cofactor and numerous [4Fe-4S] clusters. In some organisms an additional subunit enables the incorporation of tungsten when molybdenum availability is low. The enzyme catalyses a reversible reaction in methanogenic archaea, and is involved in methanogenesis from CO2 as well as the oxidation of coenzyme M to CO2. The reaction is endergonic, and is driven by coupling with the soluble CoB-CoM heterodisulfide reductase via electron bifurcation.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, UM-BBD, CAS registry number: 119940-12-4
References:
1.  Karrasch, M., Börner, G., Enssle, M. and Thauer, R.K. The molybdoenzyme formylmethanofuran dehydrogenase from Methanosarcina barkeri contains a pterin cofactor. Eur. J. Biochem. 194 (1990) 367–372. [DOI] [PMID: 2125267]
2.  Bertram, P.A., Schmitz, R.A., Linder, D. and Thauer, R.K. Tungstate can substitute for molybdate in sustaining growth of Methanobacterium thermoautotrophicum. Identification and characterization of a tungsten isoenzyme of formylmethanofuran dehydrogenase. Arch. Microbiol. 161 (1994) 220–228. [PMID: 8161283]
3.  Bertram, P.A., Karrasch, M., Schmitz, R.A., Bocher, R., Albracht, S.P. and Thauer, R.K. Formylmethanofuran dehydrogenases from methanogenic Archaea. Substrate specificity, EPR properties and reversible inactivation by cyanide of the molybdenum or tungsten iron-sulfur proteins. Eur. J. Biochem. 220 (1994) 477–484. [DOI] [PMID: 8125106]
4.  Vorholt, J.A. and Thauer, R.K. The active species of ’CO2’ utilized by formylmethanofuran dehydrogenase from methanogenic Archaea. Eur. J. Biochem. 248 (1997) 919–924. [DOI] [PMID: 9342247]
5.  Meuer, J., Kuettner, H.C., Zhang, J.K., Hedderich, R. and Metcalf, W.W. Genetic analysis of the archaeon Methanosarcina barkeri Fusaro reveals a central role for Ech hydrogenase and ferredoxin in methanogenesis and carbon fixation. Proc. Natl. Acad. Sci. USA 99 (2002) 5632–5637. [DOI] [PMID: 11929975]
6.  Kaster, A.K., Moll, J., Parey, K. and Thauer, R.K. Coupling of ferredoxin and heterodisulfide reduction via electron bifurcation in hydrogenotrophic methanogenic archaea. Proc. Natl. Acad. Sci. USA 108 (2011) 2981–2986. [DOI] [PMID: 21262829]
7.  Wagner, T., Ermler, U. and Shima, S. The methanogenic CO2 reducing-and-fixing enzyme is bifunctional and contains 46 [4Fe-4S] clusters. Science 354 (2016) 114–117. [PMID: 27846502]
[EC 1.2.7.12 created 1992 as EC 1.2.99.5, transferred 2017 to EC 1.2.7.12]
 
 
EC 1.2.99.5      
Transferred entry: formylmethanofuran dehydrogenase. Now EC 1.2.7.12, formylmethanofuran dehydrogenase
[EC 1.2.99.5 created 1992, deleted 2017]
 
 
EC 1.3.4.1     
Accepted name: fumarate reductase (CoM/CoB)
Reaction: fumarate + CoM + CoB = succinate + CoM-S-S-CoB
Glossary: CoB = coenzyme B = N-(7-mercaptoheptanoyl)threonine 3-O-phosphate = N-(7-thioheptanoyl)-3-O-phosphothreonine
CoM = coenzyme M = 2-mercaptoethanesulfonate
Other name(s): thiol:fumarate reductase; Tfr
Systematic name: fumarate CoM:CoB oxidoreductase (succinate-forming)
Comments: The enzyme, isolated from the archaeon Methanobacterium thermoautotrophicum, is very oxygen sensitive. It cannot use reduced flavins, reduced coenzyme F420, or NAD(P)H as an electron donor. Distinct from EC 1.3.1.6 [fumarate reductase (NADH)], EC 1.3.5.1 [succinate dehydrogenase (ubiquinone)], and EC 1.3.5.4 [fumarate reductase (quinol)].
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Khandekar, S.S. and Eirich, L.D. Purification and characterization of an anabolic fumarate reductase from Methanobacterium thermoautotrophicum. Appl. Environ. Microbiol. 55 (1989) 856–861. [PMID: 2499256]
2.  Heim, S., Kunkel, A., Thauer, R.K. and Hedderich, R. Thiol:fumarate reductase (Tfr) from Methanobacterium thermoautotrophicum. Identification of the catalytic sites for fumarate reduction and thiol oxidation. Eur. J. Biochem. 253 (1998) 292–299. [DOI] [PMID: 9578488]
[EC 1.3.4.1 created 2014 as EC 1.3.98.2, transferred 2014 to EC 1.3.4.1]
 
 
EC 1.8.1.5     
Accepted name: 2-oxopropyl-CoM reductase (carboxylating)
Reaction: 2-mercaptoethanesulfonate + acetoacetate + NADP+ = 2-(2-oxopropylthio)ethanesulfonate + CO2 + NADPH
For diagram of epoxide carboxylation, click here
Glossary: coenzyme M (CoM) = 2-mercaptoethanesulfonate
Other name(s): NADPH:2-(2-ketopropylthio)ethanesulfonate oxidoreductase/carboxylase; NADPH:2-ketopropyl-coenzyme M oxidoreductase/carboxylase
Systematic name: 2-mercaptoethanesulfonate,acetoacetate:NADP+ oxidoreductase (decarboxylating)
Comments: Also acts on thioethers longer in chain length on the oxo side, e.g. 2-oxobutyl-CoM, but this portion must be attached to CoM (2-mercaptoethanesulfonate); no CoM analogs will substitute. This enzyme forms component II of a four-component enzyme system {comprising EC 4.4.1.23 (2-hydroxypropyl-CoM lyase; component I), EC 1.8.1.5 [2-oxopropyl-CoM reductase (carboxylating); component II], EC 1.1.1.268 [2-(R)-hydroxypropyl-CoM dehydrogenase; component III] and EC 1.1.1.269 [2-(S)-hydroxypropyl-CoM dehydrogenase; component IV]} that is involved in epoxyalkane carboxylation in Xanthobacter sp. strain Py2.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, UM-BBD, CAS registry number: 244301-63-1
References:
1.  Allen, J.R., Clark, D.D., Krum, J.G. and Ensign, S.A. A role for coenzyme M (2-mercaptoethanesulfonic acid) in a bacterial pathway of aliphatic epoxide carboxylation. Proc. Natl. Acad. Sci. USA 96 (1999) 8432–8437. [DOI] [PMID: 10411892]
2.  Clark, D.D., Allen, J.R. and Ensign, S.A. Characterization of five catalytic activities associated with the NADPH:2-ketopropyl-coenzyme M [2-(2-ketopropylthio)ethanesulfonate] oxidoreductase/carboxylase of the Xanthobacter strain Py2 epoxide carboxylase system. Biochemistry 39 (2000) 1294–1304. [DOI] [PMID: 10684609]
[EC 1.8.1.5 created 2001]
 
 
EC 1.8.7.3     
Accepted name: ferredoxin:CoB-CoM heterodisulfide reductase
Reaction: 2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM = 2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
Glossary: CoB = coenzyme B = N-(7-mercaptoheptanoyl)threonine 3-O-phosphate = N-(7-thioheptanoyl)-3-O-phosphothreonine
CoM = coenzyme M = 2-mercaptoethanesulfonate
CoM-S-S-CoB = CoB-CoM heterodisulfide = N-{7-[(2-sulfoethyl)dithio]heptanoyl}-O3-phospho-L-threonine
Other name(s): hdrABC (gene names); hdrA1B1C1 (gene names); hdrA2B2C2 (gene names)
Systematic name: CoB,CoM:ferredoxin oxidoreductase
Comments: HdrABC is an enzyme complex that is found in most methanogens and catalyses the reduction of the CoB-CoM heterodisulfide back to CoB and CoM. HdrA contains a FAD cofactor that acts as the entry point for electrons, which are transferred via HdrC to the HdrB catalytic subunit. One form of the enzyme from Methanosarcina acetivorans (HdrA2B2C2) can also catalyse EC 1.8.98.4, coenzyme F420:CoB-CoM heterodisulfide,ferredoxin reductase. cf. EC 1.8.98.5, H2:CoB-CoM heterodisulfide,ferredoxin reductase, EC 1.8.98.6, formate:CoB-CoM heterodisulfide,ferredoxin reductase, and EC 1.8.98.1, dihydromethanophenazine:CoB-CoM heterodisulfide reductase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Buan, N.R. and Metcalf, W.W. Methanogenesis by Methanosarcina acetivorans involves two structurally and functionally distinct classes of heterodisulfide reductase. Mol. Microbiol. 75 (2010) 843–853. [DOI] [PMID: 19968794]
2.  Yan, Z., Wang, M. and Ferry, J.G. A ferredoxin- and F420H2-dependent, electron-bifurcating, heterodisulfide reductase with homologs in the domains Bacteria and Archaea. mBio 8 (2017) e02285-16. [DOI] [PMID: 28174314]
[EC 1.8.7.3 created 2017]
 
 
EC 1.8.98.1     
Accepted name: dihydromethanophenazine:CoB-CoM heterodisulfide reductase
Reaction: CoB + CoM + methanophenazine = CoM-S-S-CoB + dihydromethanophenazine
For diagram of methane biosynthesis, click here
Glossary: CoB = coenzyme B = N-(7-mercaptoheptanoyl)threonine 3-O-phosphate
CoM = coenzyme M = 2-mercaptoethanesulfonate
methanophenazine = 2-{[(6E,10E,14E)-3,7,11,15,19-pentamethylicosa-6,10,14,18-tetraen-1-yl]oxy}phenazine
CoM-S-S-CoB = CoB-CoM heterodisulfide = N-{7-[(2-sulfoethyl)dithio]heptanoyl}-O3-phospho-L-threonine
Other name(s): hdrDE (gene names); CoB—CoM heterodisulfide reductase (ambiguous); heterodisulfide reductase (ambiguous); coenzyme B:coenzyme M:methanophenazine oxidoreductase
Systematic name: CoB:CoM:methanophenazine oxidoreductase
Comments: This enzyme, found in methanogenic archaea that belong to the Methanosarcinales order, regenerates CoM and CoB after the action of EC 2.8.4.1, coenzyme-B sulfoethylthiotransferase. It is a membrane-bound enzyme that contains (per heterodimeric unit) two distinct b-type hemes and two [4Fe-4S] clusters. cf. EC 1.8.7.3, ferredoxin:CoB-CoM heterodisulfide reductase, EC 1.8.98.5, H2:CoB-CoM heterodisulfide,ferredoxin reductase, EC 1.8.98.6, formate:CoB-CoM heterodisulfide,ferredoxin reductase and EC 1.8.98.4, coenzyme F420:CoB-CoM heterodisulfide,ferredoxin reductase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Hedderich, R., Berkessel, A. and Thauer, R.K. Purification and properties of heterodisulfide reductase from Methanobacterium thermoautotrophicum (strain Marburg). Eur. J. Biochem. 193 (1990) 255–261. [DOI] [PMID: 2121478]
2.  Abken, H.J., Tietze, M., Brodersen, J., Bäumer, S., Beifuss, U. and Deppenmeier, U. Isolation and characterization of methanophenazine and function of phenazines in membrane-bound electron transport of Methanosarcina mazei gol. J. Bacteriol. 180 (1998) 2027–2032. [PMID: 9555882]
3.  Simianu, M., Murakami, E., Brewer, J.M. and Ragsdale, S.W. Purification and properties of the heme- and iron-sulfur-containing heterodisulfide reductase from Methanosarcina thermophila. Biochemistry 37 (1998) 10027–10039. [DOI] [PMID: 9665708]
4.  Murakami, E., Deppenmeier, U. and Ragsdale, S.W. Characterization of the intramolecular electron transfer pathway from 2-hydroxyphenazine to the heterodisulfide reductase from Methanosarcina thermophila. J. Biol. Chem. 276 (2001) 2432–2439. [DOI] [PMID: 11034998]
[EC 1.8.98.1 created 2003, modified 2017]
 
 
EC 1.8.98.4     
Accepted name: coenzyme F420:CoB-CoM heterodisulfide,ferredoxin reductase
Reaction: 2 oxidized coenzyme F420 + 2 reduced ferredoxin [iron-sulfur] cluster + CoB + CoM + 2 H+ = 2 reduced coenzyme F420 + 2 oxidized ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB
Glossary: CoB = coenzyme B = N-(7-mercaptoheptanoyl)threonine 3-O-phosphate = N-(7-thioheptanoyl)-3-O-phosphothreonine
CoM = coenzyme M = 2-mercaptoethanesulfonate
CoM-S-S-CoB = CoB-CoM heterodisulfide = N-{7-[(2-sulfoethyl)dithio]heptanoyl}-O3-phospho-L-threonine
Other name(s): hdrA2B2C2 (gene names)
Systematic name: CoB,CoM,ferredoxin:coenzyme F420 oxidoreductase
Comments: The enzyme, characterized from the archaeon Methanosarcina acetivorans, catalyses the reduction of CoB-CoM heterodisulfide back to CoB and CoM. The enzyme consists of three components, HdrA, HdrB and HdrC, all of which contain [4Fe-4S] clusters. Electrons enter at HdrA, which also contains FAD, and are transferred via HdrC to the catalytic component, HdrB. During methanogenesis from acetate the enzyme catalyses the activity of EC 1.8.7.3, ferredoxin:CoB-CoM heterodisulfide reductase. However, it can also use electron bifurcation to direct electron pairs from reduced coenzyme F420 towards the reduction of both ferredoxin and CoB-CoM heterodisulfide. This activity is proposed to take place during Fe(III)-dependent anaerobic methane oxidation. cf. EC 1.8.98.5, H2:CoB-CoM heterodisulfide,ferredoxin reductase, EC 1.8.98.6, formate:CoB-CoM heterodisulfide,ferredoxin reductase, and EC 1.8.98.1, dihydromethanophenazine:CoB-CoM heterodisulfide reductase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Yan, Z., Wang, M. and Ferry, J.G. A ferredoxin- and F420H2-dependent, electron-bifurcating, heterodisulfide reductase with homologs in the domains Bacteria and Archaea. mBio 8 (2017) e02285-16. [DOI] [PMID: 28174314]
[EC 1.8.98.4 created 2017]
 
 
EC 1.8.98.5     
Accepted name: H2:CoB-CoM heterodisulfide,ferredoxin reductase
Reaction: 2 reduced ferredoxin [iron-sulfur] cluster + CoB + CoM + 2 H+ = 2 H2 + 2 oxidized ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB
Glossary: CoB = coenzyme B = N-(7-mercaptoheptanoyl)threonine 3-O-phosphate = N-(7-thioheptanoyl)-3-O-phosphothreonine
CoM = coenzyme M = 2-mercaptoethanesulfonate
CoM-S-S-CoB = CoB-CoM heterodisulfide = N-{7-[(2-sulfoethyl)dithio]heptanoyl}-O3-phospho-L-threonine
Systematic name: CoB,CoM,ferredoxin:H2 oxidoreductase
Comments: This enzyme complex is found in H2-oxidizing CO2-reducing methanogenic archaea such as Methanothermobacter thermautotrophicus. It consists of a cytoplasmic complex of HdrABC reductase and MvhAGD hydrogenase. Electron pairs donated by the hydrogenase are transferred via its δ subunit to the HdrA subunit of the reductase, where they are bifurcated, reducing both ferredoxin and CoB-CoM heterodisulfide. The reductase can also form a similar complex with formate dehydrogenase, see EC 1.8.98.6, formate:CoB-CoM heterodisulfide,ferredoxin reductase. cf. EC 1.8.7.3, ferredoxin:CoB-CoM heterodisulfide reductase, EC 1.8.98.4, coenzyme F420:CoB-CoM heterodisulfide,ferredoxin reductase, and EC 1.8.98.1, dihydromethanophenazine:CoB-CoM heterodisulfide reductase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Reeve, J.N., Beckler, G.S., Cram, D.S., Hamilton, P.T., Brown, J.W., Krzycki, J.A., Kolodziej, A.F., Alex, L., Orme-Johnson, W.H. and Walsh, C.T. A hydrogenase-linked gene in Methanobacterium thermoautotrophicum strain δ H encodes a polyferredoxin. Proc. Natl. Acad. Sci. USA 86 (1989) 3031–3035. [DOI] [PMID: 2654933]
2.  Hedderich, R., Koch, J., Linder, D. and Thauer, R.K. The heterodisulfide reductase from Methanobacterium thermoautotrophicum contains sequence motifs characteristic of pyridine-nucleotide-dependent thioredoxin reductases. Eur. J. Biochem. 225 (1994) 253–261. [DOI] [PMID: 7925445]
3.  Setzke, E., Hedderich, R., Heiden, S. and Thauer, R.K. H2: heterodisulfide oxidoreductase complex from Methanobacterium thermoautotrophicum. Composition and properties. Eur. J. Biochem. 220 (1994) 139–148. [DOI] [PMID: 8119281]
4.  Stojanowic, A., Mander, G.J., Duin, E.C. and Hedderich, R. Physiological role of the F420-non-reducing hydrogenase (Mvh) from Methanothermobacter marburgensis. Arch. Microbiol. 180 (2003) 194–203. [DOI] [PMID: 12856108]
5.  Kaster, A.K., Moll, J., Parey, K. and Thauer, R.K. Coupling of ferredoxin and heterodisulfide reduction via electron bifurcation in hydrogenotrophic methanogenic archaea. Proc. Natl. Acad. Sci. USA 108 (2011) 2981–2986. [DOI] [PMID: 21262829]
6.  Costa, K.C., Lie, T.J., Xia, Q. and Leigh, J.A. VhuD facilitates electron flow from H2 or formate to heterodisulfide reductase in Methanococcus maripaludis. J. Bacteriol. 195 (2013) 5160–5165. [DOI] [PMID: 24039260]
[EC 1.8.98.5 created 2017]
 
 
EC 1.8.98.6     
Accepted name: formate:CoB-CoM heterodisulfide,ferredoxin reductase
Reaction: 2 CO2 + 2 reduced ferredoxin [iron-sulfur] cluster + CoB + CoM + 2 H+ = 2 formate + 2 oxidized ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB
Glossary: coenzyme B = CoB = N-(7-mercaptoheptanoyl)threonine 3-O-phosphate = N-(7-thioheptanoyl)-3-O-phosphothreonine
coenzyme M = CoM = 2-mercaptoethanesulfonate
CoM-S-S-CoB = CoB-CoM heterodisulfide = N-{7-[(2-sulfoethyl)dithio]heptanoyl}-O3-phospho-L-threonine
Systematic name: coenzyme B,coenzyme M,ferredoxin:formate oxidoreductase
Comments: The enzyme is found in formate-oxidizing CO2-reducing methanogenic archaea such as Methanococcus maripaludis. It consists of a cytoplasmic complex of HdrABC reductase and formate dehydrogenase. Electron pairs donated by formate dehydrogenase are transferred to the HdrA subunit of the reductase, where they are bifurcated, reducing both ferredoxin and CoB-CoM heterodisulfide. cf. EC 1.8.7.3, ferredoxin:CoB-CoM heterodisulfide reductase, EC 1.8.98.4, coenzyme F420:CoB-CoM heterodisulfide,ferredoxin reductase, EC 1.8.98.5, H2:CoB-CoM heterodisulfide,ferredoxin reductase, and EC 1.8.98.1, dihydromethanophenazine:CoB-CoM heterodisulfide reductase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Costa, K.C., Wong, P.M., Wang, T., Lie, T.J., Dodsworth, J.A., Swanson, I., Burn, J.A., Hackett, M. and Leigh, J.A. Protein complexing in a methanogen suggests electron bifurcation and electron delivery from formate to heterodisulfide reductase. Proc. Natl. Acad. Sci. USA 107 (2010) 11050–11055. [DOI] [PMID: 20534465]
2.  Costa, K.C., Lie, T.J., Xia, Q. and Leigh, J.A. VhuD facilitates electron flow from H2 or formate to heterodisulfide reductase in Methanococcus maripaludis. J. Bacteriol. 195 (2013) 5160–5165. [DOI] [PMID: 24039260]
[EC 1.8.98.6 created 2017]
 
 
EC 2.1.1.86     
Accepted name: tetrahydromethanopterin S-methyltransferase
Reaction: 5-methyl-5,6,7,8-tetrahydromethanopterin + CoM + 2 Na+in = 5,6,7,8-tetrahydromethanopterin + 2-(methylsulfanyl)ethane-1-sulfonate + 2 Na+out
For diagram of methane biosynthesis, click here
Glossary: CoM = coenzyme M = 2-sulfanylethane-1-sulfonate
tetrahydromethanopterin = 1-(4-{(1R)-1-[(6S,7S)-2-amino-7-methyl-4-oxo-3,4,5,6,7,8-hexahydropteridin-6-yl]ethylamino}phenyl)-1-deoxy-5-O-{5-O-[(1S)-1,3-dicarboxypropylphosphonato]-α-D-ribofuranosyl}-D-ribitol
Other name(s): tetrahydromethanopterin methyltransferase; mtrA-H (gene names); cmtA (gene name); N5-methyltetrahydromethanopterin—coenzyme M methyltransferase; 5-methyl-5,6,7,8-tetrahydromethanopterin:2-mercaptoethanesulfonate 2-methyltransferase
Systematic name: 5-methyl-5,6,7,8-tetrahydromethanopterin:CoM 2-methyltransferase (Na+-transporting)
Comments: Involved in the formation of methane from CO2 in methanogenic archaea. The reaction involves the export of one or two sodium ions. The enzyme from the archaeon Methanobacterium thermoautotrophicum is a membrane-associated multienzyme complex composed of eight different subunits, and contains a 5′-hydroxybenzimidazolyl-cobamide prosthetic group, to which the methyl group is attached during the transfer. A soluble enzyme that is induced by the presence of CO has been reported as well [6].
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, UM-BBD, CAS registry number: 103406-60-6
References:
1.  Sauer, F.D. Tetrahydromethanopterin methyltransferase, a component of the methane synthesizing complex of Methanobacterium thermoautotrophicum. Biochem. Biophys. Res. Commun. 136 (1986) 542–547. [DOI] [PMID: 3085670]
2.  Gartner, P., Ecker, A., Fischer, R., Linder, D., Fuchs, G. and Thauer, R.K. Purification and properties of N5-methyltetrahydromethanopterin:coenzyme M methyltransferase from Methanobacterium thermoautotrophicum. Eur. J. Biochem. 213 (1993) 537–545. [DOI] [PMID: 8477726]
3.  Weiss, D.S., Gartner, P. and Thauer, R.K. The energetics and sodium-ion dependence of N5-methyltetrahydromethanopterin:coenzyme M methyltransferase studied with cob(I)alamin as methyl acceptor and methylcob(III)alamin as methyl donor. Eur. J. Biochem. 226 (1994) 799–809. [DOI] [PMID: 7813469]
4.  Harms, U., Weiss, D.S., Gartner, P., Linder, D. and Thauer, R.K. The energy conserving N5-methyltetrahydromethanopterin:coenzyme M methyltransferase complex from Methanobacterium thermoautotrophicum is composed of eight different subunits. Eur. J. Biochem. 228 (1995) 640–648. [DOI] [PMID: 7737157]
5.  Gottschalk, G. and Thauer, R.K. The Na(+)-translocating methyltransferase complex from methanogenic archaea. Biochim. Biophys. Acta 1505 (2001) 28–36. [DOI] [PMID: 11248186]
6.  Vepachedu, V.R. and Ferry, J.G. Role of the fused corrinoid/methyl transfer protein CmtA during CO-dependent growth of Methanosarcina acetivorans. J. Bacteriol. 194 (2012) 4161–4168. [DOI] [PMID: 22636775]
[EC 2.1.1.86 created 1989, modified 2000, modified 2017]
 
 
EC 2.1.1.90     
Accepted name: methanol—corrinoid protein Co-methyltransferase
Reaction: methanol + a [Co(I) methanol-specific corrinoid protein] = a [methyl-Co(III) methanol-specific corrinoid protein] + H2O
Other name(s): methanol cobalamin methyltransferase; methanol:5-hydroxybenzimidazolylcobamide methyltransferase; MT 1 (ambiguous); methanol—5-hydroxybenzimidazolylcobamide Co-methyltransferase; mtaB (gene name)
Systematic name: methanol:5-hydroxybenzimidazolylcobamide Co-methyltransferase
Comments: The enzyme, which catalyses the transfer of methyl groups from methanol to a methanol-specific corrinoid protein (MtaC), is involved in methanogenesis from methanol. Methylation of the corrinoid protein requires the central cobalt to be in the Co(I) state. During methylation the cobalt is oxidized to the Co(III) state. Free cob(I)alamin can substitute for the corrinoid protein in vitro [2]. Inactivated by oxygen and other oxidizing agents, and reactivated by catalytic amounts of ATP and hydrogen.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 86611-98-5
References:
1.  van der Meijden, P., te Brömmelstroet, B.W., Poirot, C.M., van der Drift, C. and Vogels, G.D. Purification and properties of methanol:5-hydroxybenzimidazolylcobamide methyltransferase from Methanosarcina barkeri. J. Bacteriol. 160 (1984) 629–635. [PMID: 6438059]
2.  Sauer, K. and Thauer, R.K. Methanol:coenzyme M methyltransferase from Methanosarcina barkeri – substitution of the corrinoid harbouring subunit MtaC by free cob(I)alamin. Eur. J. Biochem. 261 (1999) 674–681. [DOI] [PMID: 10215883]
[EC 2.1.1.90 created 1989, modified 2012]
 
 
EC 2.1.1.246     
Accepted name: [methyl-Co(III) methanol-specific corrinoid protein]—coenzyme M methyltransferase
Reaction: a [methyl-Co(III) methanol-specific corrinoid protein] + CoM = methyl-CoM + a [Co(I) methanol-specific corrinoid protein]
Glossary: CoM = coenzyme M = 2-mercaptoethanesulfonate
Other name(s): methyltransferase 2 (ambiguous); mtaA (gene name)
Systematic name: methylated methanol-specific corrinoid protein:CoM methyltransferase
Comments: The enzyme, which is involved in methanogenesis from methanol, catalyses the transfer of a methyl group from a corrinoid protein (see EC 2.1.1.90, methanol—corrinoid protein Co-methyltransferase), where it is bound to the cobalt cofactor, to CoM, forming the substrate for EC 2.8.4.1, coenzyme-B sulfoethylthiotransferase, the enzyme that catalyses the final step in methanogenesis. Free methylcob(I)alamin can substitute for the corrinoid protein in vitro [5].
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  LeClerc, G.M. and Grahame, D.A. Methylcobamide:coenzyme M methyltransferase isozymes from Methanosarcina barkeri. Physicochemical characterization, cloning, sequence analysis, and heterologous gene expression. J. Biol. Chem. 271 (1996) 18725–18731. [DOI] [PMID: 8702528]
2.  Harms, U. and Thauer, R.K. Methylcobalamin: coenzyme M methyltransferase isoenzymes MtaA and MtbA from Methanosarcina barkeri. Cloning, sequencing and differential transcription of the encoding genes, and functional overexpression of the mtaA gene in Escherichia coli. Eur. J. Biochem. 235 (1996) 653–659. [DOI] [PMID: 8654414]
3.  Sauer, K. and Thauer, R.K. Methanol:coenzyme M methyltransferase from Methanosarcina barkeri. Zinc dependence and thermodynamics of the methanol:cob(I)alamin methyltransferase reaction. Eur. J. Biochem. 249 (1997) 280–285. [DOI] [PMID: 9363780]
4.  Sauer, K., Harms, U. and Thauer, R.K. Methanol:coenzyme M methyltransferase from Methanosarcina barkeri. Purification, properties and encoding genes of the corrinoid protein MT1. Eur. J. Biochem. 243 (1997) 670–677. [DOI] [PMID: 9057830]
5.  Sauer, K. and Thauer, R.K. Methanol:coenzyme M methyltransferase from Methanosarcina barkeri – substitution of the corrinoid harbouring subunit MtaC by free cob(I)alamin. Eur. J. Biochem. 261 (1999) 674–681. [DOI] [PMID: 10215883]
[EC 2.1.1.246 created 2012]
 
 
EC 2.1.1.247     
Accepted name: [methyl-Co(III) methylamine-specific corrinoid protein]—coenzyme M methyltransferase
Reaction: a [methyl-Co(III) methylamine-specific corrinoid protein] + CoM = methyl-CoM + a [Co(I) methylamine-specific corrinoid protein]
Glossary: CoM = coenzyme M = 2-mercaptoethanesulfonate
Other name(s): methyltransferase 2 (ambiguous); MT2 (ambiguous); MT2-A; mtbA (gene name); [methyl-Co(III) methylamine-specific corrinoid protein]:coenzyme M methyltransferase
Systematic name: methylated monomethylamine-specific corrinoid protein:CoM methyltransferase
Comments: Contains zinc [2]. The enzyme, which is involved in methanogenesis from mono-, di-, and trimethylamine, catalyses the transfer of a methyl group bound to the cobalt cofactor of several corrinoid proteins (mono-, di-, and trimethylamine-specific corrinoid proteins, cf. EC 2.1.1.248, methylamine—corrinoid protein Co-methyltransferase, EC 2.1.1.249, dimethylamine—corrinoid protein Co-methyltransferase, and EC 2.1.1.250, trimethylamine—corrinoid protein Co-methyltransferase) to CoM, forming the substrate for EC 2.8.4.1, coenzyme-B sulfoethylthiotransferase, the enzyme that catalyses the final step in methanogenesis.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Burke, S.A. and Krzycki, J.A. Involvement of the "A" isozyme of methyltransferase II and the 29-kilodalton corrinoid protein in methanogenesis from monomethylamine. J. Bacteriol. 177 (1995) 4410–4416. [DOI] [PMID: 7635826]
2.  LeClerc, G.M. and Grahame, D.A. Methylcobamide:coenzyme M methyltransferase isozymes from Methanosarcina barkeri. Physicochemical characterization, cloning, sequence analysis, and heterologous gene expression. J. Biol. Chem. 271 (1996) 18725–18731. [DOI] [PMID: 8702528]
3.  Ferguson, D.J., Jr. and Krzycki, J.A. Reconstitution of trimethylamine-dependent coenzyme M methylation with the trimethylamine corrinoid protein and the isozymes of methyltransferase II from Methanosarcina barkeri. J. Bacteriol. 179 (1997) 846–852. [DOI] [PMID: 9006042]
4.  Burke, S.A., Lo, S.L. and Krzycki, J.A. Clustered genes encoding the methyltransferases of methanogenesis from monomethylamine. J. Bacteriol. 180 (1998) 3432–3440. [PMID: 9642198]
5.  Ferguson, D.J., Jr., Gorlatova, N., Grahame, D.A. and Krzycki, J.A. Reconstitution of dimethylamine:coenzyme M methyl transfer with a discrete corrinoid protein and two methyltransferases purified from Methanosarcina barkeri. J. Biol. Chem. 275 (2000) 29053–29060. [DOI] [PMID: 10852929]
[EC 2.1.1.247 created 2012]
 
 
EC 2.1.1.248     
Accepted name: methylamine—corrinoid protein Co-methyltransferase
Reaction: methylamine + a [Co(I) methylamine-specific corrinoid protein] = a [methyl-Co(III) methylamine-specific corrinoid protein] + NH3
Other name(s): mtmB (gene name); monomethylamine methyltransferase
Systematic name: monomethylamine:5-hydroxybenzimidazolylcobamide Co-methyltransferase
Comments: The enzyme, which catalyses the transfer of a methyl group from methylamine to a methylamine-specific corrinoid protein (MtmC), is involved in methanogenesis from methylamine. The enzyme contains the unusual amino acid pyrrolysine [3]. Methylation of the corrinoid protein requires the central cobalt to be in the Co(I) state. During methylation the cobalt is oxidized to the Co(III) state. The methylated corrinoid protein is substrate for EC 2.1.1.247, methylated methylamine-specific corrinoid protein:coenzyme M methyltransferase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Burke, S.A. and Krzycki, J.A. Reconstitution of Monomethylamine:Coenzyme M methyl transfer with a corrinoid protein and two methyltransferases purified from Methanosarcina barkeri. J. Biol. Chem. 272 (1997) 16570–16577. [DOI] [PMID: 9195968]
2.  Burke, S.A., Lo, S.L. and Krzycki, J.A. Clustered genes encoding the methyltransferases of methanogenesis from monomethylamine. J. Bacteriol. 180 (1998) 3432–3440. [PMID: 9642198]
3.  Krzycki, J.A. Function of genetically encoded pyrrolysine in corrinoid-dependent methylamine methyltransferases. Curr. Opin. Chem. Biol. 8 (2004) 484–491. [DOI] [PMID: 15450490]
[EC 2.1.1.248 created 2012]
 
 
EC 2.1.1.249     
Accepted name: dimethylamine—corrinoid protein Co-methyltransferase
Reaction: dimethylamine + a [Co(I) dimethylamine-specific corrinoid protein] = a [methyl-Co(III) dimethylamine-specific corrinoid protein] + methylamine
Other name(s): mtbB (gene name); dimethylamine methyltransferase
Systematic name: dimethylamine:5-hydroxybenzimidazolylcobamide Co-methyltransferase
Comments: The enzyme, which catalyses the transfer of a methyl group from dimethylamine to a dimethylamine-specific corrinoid protein (MtbC), is involved in methanogenesis from dimethylamine. The enzyme contains the unusual amino acid pyrrolysine [3]. Methylation of the corrinoid protein requires the central cobalt to be in the Co(I) state. During methylation the cobalt is oxidized to the Co(III) state. The methylated corrinoid protein is substrate for EC 2.1.1.247, methylated methylamine-specific corrinoid protein:coenzyme M methyltransferase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Wassenaar, R.W., Keltjens, J.T., van der Drift, C. and Vogels, G.D. Purification and characterization of dimethylamine:5-hydroxybenzimidazolyl-cobamide methyltransferase from Methanosarcina barkeri Fusaro. Eur. J. Biochem. 253 (1998) 692–697. [DOI] [PMID: 9654067]
2.  Ferguson, D.J., Jr., Gorlatova, N., Grahame, D.A. and Krzycki, J.A. Reconstitution of dimethylamine:coenzyme M methyl transfer with a discrete corrinoid protein and two methyltransferases purified from Methanosarcina barkeri. J. Biol. Chem. 275 (2000) 29053–29060. [DOI] [PMID: 10852929]
3.  Krzycki, J.A. Function of genetically encoded pyrrolysine in corrinoid-dependent methylamine methyltransferases. Curr. Opin. Chem. Biol. 8 (2004) 484–491. [DOI] [PMID: 15450490]
[EC 2.1.1.249 created 2012]
 
 
EC 2.1.1.250     
Accepted name: trimethylamine—corrinoid protein Co-methyltransferase
Reaction: trimethylamine + a [Co(I) trimethylamine-specific corrinoid protein] = a [methyl-Co(III) trimethylamine-specific corrinoid protein] + dimethylamine
Other name(s): mttB (gene name); trimethylamine methyltransferase
Systematic name: trimethylamine:5-hydroxybenzimidazolylcobamide Co-methyltransferase
Comments: The enzyme, which catalyses the transfer of a methyl group from trimethylamine to a trimethylamine-specific corrinoid protein (MttC), is involved in methanogenesis from trimethylamine. The enzyme contains the unusual amino acid pyrrolysine [2]. Methylation of the corrinoid protein requires the central cobalt to be in the Co(I) state. During methylation the cobalt is oxidized to the Co(III) state. The methylated corrinoid protein is substrate for EC 2.1.1.247, methylated methylamine-specific corrinoid protein:coenzyme M methyltransferase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Ferguson, D.J., Jr. and Krzycki, J.A. Reconstitution of trimethylamine-dependent coenzyme M methylation with the trimethylamine corrinoid protein and the isozymes of methyltransferase II from Methanosarcina barkeri. J. Bacteriol. 179 (1997) 846–852. [DOI] [PMID: 9006042]
2.  Krzycki, J.A. Function of genetically encoded pyrrolysine in corrinoid-dependent methylamine methyltransferases. Curr. Opin. Chem. Biol. 8 (2004) 484–491. [DOI] [PMID: 15450490]
[EC 2.1.1.250 created 2012]
 
 
EC 2.1.1.251     
Accepted name: methylated-thiol—coenzyme M methyltransferase
Reaction: methanethiol + CoM = methyl-CoM + hydrogen sulfide (overall reaction)
(1a) methanethiol + a [Co(I) methylated-thiol-specific corrinoid protein] = a [methyl-Co(III) methylated-thiol-specific corrinoid protein] + hydrogen sulfide
(1b) a [methyl-Co(III) methylated-thiol-specific corrinoid protein] + CoM = methyl-CoM + a [Co(I) methylated-thiol-specific corrinoid protein]
Glossary: CoM = coenzyme M = 2-mercaptoethanesulfonate
Other name(s): mtsA (gene name)
Systematic name: methylated-thiol:CoM methyltransferase
Comments: The enzyme, which is involved in methanogenesis from methylated thiols, such as methane thiol, dimethyl sulfide, and 3-S-methylmercaptopropionate, catalyses two successive steps - the transfer of a methyl group from the substrate to the cobalt cofactor of a methylated-thiol-specific corrinoid protein (MtsB), and the subsequent transfer of the methyl group from the corrinoid protein to CoM. With most other methanogenesis substrates this process is carried out by two different enzymes (for example, EC 2.1.1.90, methanol—corrinoid protein Co-methyltransferase, and EC 2.1.1.246, methylated methanol-specific corrinoid protein:coenzyme M methyltransferase). The cobalt is oxidized during methylation from the Co(I) state to the Co(III) state, and is reduced back to the Co(I) form during demethylation.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Paul, L. and Krzycki, J.A. Sequence and transcript analysis of a novel Methanosarcina barkeri methyltransferase II homolog and its associated corrinoid protein homologous to methionine synthase. J. Bacteriol. 178 (1996) 6599–6607. [DOI] [PMID: 8932317]
2.  Tallant, T.C. and Krzycki, J.A. Methylthiol:coenzyme M methyltransferase from Methanosarcina barkeri, an enzyme of methanogenesis from dimethylsulfide and methylmercaptopropionate. J. Bacteriol. 179 (1997) 6902–6911. [DOI] [PMID: 9371433]
3.  Tallant, T.C., Paul, L. and Krzycki, J.A. The MtsA subunit of the methylthiol:coenzyme M methyltransferase of Methanosarcina barkeri catalyses both half-reactions of corrinoid-dependent dimethylsulfide: coenzyme M methyl transfer. J. Biol. Chem. 276 (2001) 4485–4493. [DOI] [PMID: 11073950]
[EC 2.1.1.251 created 2012]
 
 
EC 2.1.1.252     
Accepted name: tetramethylammonium—corrinoid protein Co-methyltransferase
Reaction: tetramethylammonium + a [Co(I) tetramethylammonium-specific corrinoid protein] = a [methyl-Co(III) tetramethylammonium-specific corrinoid protein] + trimethylamine
Other name(s): mtqB (gene name); tetramethylammonium methyltransferase
Systematic name: tetramethylammonium:5-hydroxybenzimidazolylcobamide Co-methyltransferase
Comments: The enzyme, which catalyses the transfer of a methyl group from tetramethylammonium to a tetramethylammonium-specific corrinoid protein (MtqC), is involved in methanogenesis from tetramethylammonium. Methylation of the corrinoid protein requires the central cobalt to be in the Co(I) state. During methylation the cobalt is oxidized to the Co(III) state. The methylated corrinoid protein is substrate for EC 2.1.1.253, methylated tetramethylammonium-specific corrinoid protein:coenzyme M methyltransferase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Asakawa, S., Sauer, K., Liesack, W. and Thauer, R.K. Tetramethylammonium:coenzyme M methyltransferase system from methanococcoides s. Arch. Microbiol. 170 (1998) 220–226. [PMID: 9732435]
[EC 2.1.1.252 created 2012]
 
 
EC 2.1.1.253     
Accepted name: [methyl-Co(III) tetramethylammonium-specific corrinoid protein]—coenzyme M methyltransferase
Reaction: a [methyl-Co(III) tetramethylammonium-specific corrinoid protein] + CoM = methyl-CoM + a [Co(I) tetramethylammonium-specific corrinoid protein]
Glossary: CoM = coenzyme M = 2-mercaptoethanesulfonate
Other name(s): methyltransferase 2 (ambiguous); mtqA (gene name)
Systematic name: methylated tetramethylammonium-specific corrinoid protein:CoM methyltransferase
Comments: The enzyme, which is involved in methanogenesis from tetramethylammonium, catalyses the transfer of a methyl group from a corrinoid protein (see EC 2.1.1.252, tetramethylammonium—corrinoid protein Co-methyltransferase), where it is bound to the cobalt cofactor, to CoM, forming the substrate for EC 2.8.4.1, coenzyme-B sulfoethylthiotransferase, the enzyme that catalyses the final step in methanogenesis.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Asakawa, S., Sauer, K., Liesack, W. and Thauer, R.K. Tetramethylammonium:coenzyme M methyltransferase system from methanococcoides s. Arch. Microbiol. 170 (1998) 220–226. [PMID: 9732435]
[EC 2.1.1.253 created 2012]
 
 
EC 2.5.1.76     
Accepted name: cysteate synthase
Reaction: O-phospho-L-serine + sulfite = L-cysteate + phosphate
Other name(s): sulfite:O-phospho-L-serine sulfotransferase (phosphate-hydrolysing, L-cysteate-forming)
Systematic name: sulfite:O-phospho-L-serine sulfonotransferase (phosphate-hydrolysing, L-cysteate-forming)
Comments: A pyridoxal-phosphate protein. It is highly specific for O-phospho-L-serine and sulfite. The reaction proceeds through a dehydroalanine (2-aminoacrylic acid) intermediate. The enzyme from Methanosarcina acetivorans is evolutionarily related to threonine synthase (EC 4.2.3.1), but the reaction is more similar to that of O-phosphoserine sulfhydrylase (EC 2.5.1.65).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Graham, D.E., Taylor, S.M., Wolf, R.Z. and Namboori, S.C. Convergent evolution of coenzyme M biosynthesis in the Methanosarcinales: cysteate synthase evolved from an ancestral threonine synthase. Biochem. J. 424 (2009) 467–478. [DOI] [PMID: 19761441]
[EC 2.5.1.76 created 2009]
 
 
EC 2.8.4.1     
Accepted name: coenzyme-B sulfoethylthiotransferase
Reaction: methyl-CoM + CoB = CoM-S-S-CoB + methane
For diagram of methane biosynthesis, click here
Glossary: coenzyme B = CoB = N-(7-mercaptoheptanoyl)threonine 3-O-phosphate = N-(7-thioheptanoyl)-3-O-phosphothreonine
coenzyme M = CoM = 2-mercaptoethanesulfonate
2-(methylsulfanyl)ethanesulfonate = methyl-CoM
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.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, UM-BBD
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. [DOI] [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. [DOI] [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. [DOI] [PMID: 20520712]
[EC 2.8.4.1 created 2001, modified 2011]
 
 
EC 3.1.3.71     
Accepted name: 2-phosphosulfolactate phosphatase
Reaction: (2R)-2-phospho-3-sulfolactate + H2O = (2R)-3-sulfolactate + phosphate
For diagram of coenzyme-M biosynthesis, click here
Other name(s): (2R)-phosphosulfolactate phosphohydrolase; ComB phosphatase
Systematic name: (R)-2-phospho-3-sulfolactate phosphohydrolase
Comments: Requires Mg2+. The enzyme from Methanococcus jannaschii acts on both stereoisoimers of the substrate and also hydrolyses a number of phosphate monoesters of (S)-2-hydroxycarboxylic acids, including 2-phosphomalate, 2-phospholactate and 2-phosphoglycolate. This enzyme can also hydrolyse phosphate monoesters of (R)-2-hydroxycarboxylic acids such as (S)-2-phospho-3-sulfolactate and (R)-2-phosphomalate, which, presumably, bind to the enzyme in opposite orientations.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 409095-18-7
References:
1.  Graham, D.E., Graupner, M., Xu, H. and White, R.H. Identification of coenzyme M biosynthetic 2-phosphosulfolactate phosphatase. Eur. J. Biochem. 268 (2001) 5176–5188. [DOI] [PMID: 11589710]
[EC 3.1.3.71 created 2002]
 
 
EC 4.1.1.79     
Accepted name: sulfopyruvate decarboxylase
Reaction: 3-sulfopyruvate = 2-sulfoacetaldehyde + CO2
For diagram of coenzyme-M biosynthesis, click here
Glossary: thiamine diphosphate = 3-[(4-amino-2-methylpyrimidin-5-yl)methyl]-5-(2-diphosphoethyl)-4-methyl-1,3-thiazolium
2-sulfoacetaldehyde = 2-oxoethanesulfonate
Other name(s): sulfopyruvate carboxy-lyase
Systematic name: 3-sulfopyruvate carboxy-lyase (2-sulfoacetaldehyde-forming)
Comments: Requires thiamine diphosphate. Does not decarboxylate pyruvate or phosphonopyruvate. The enzyme appears to be oxygen-sensitive.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 303155-97-7
References:
1.  Graupner, M., Xu, H. and White, R.H. Identification of the gene encoding sulfopyruvate decarboxylase, an enzyme involved in biosynthesis of coenzyme M. J. Bacteriol. 182 (2000) 4862–4867. [DOI] [PMID: 10940029]
[EC 4.1.1.79 created 2002]
 
 
EC 4.4.1.19     
Accepted name: phosphosulfolactate synthase
Reaction: (2R)-2-O-phospho-3-sulfolactate = phosphoenolpyruvate + sulfite
For diagram of coenzyme M biosynthesis, click here
Other name(s): (2R)-phospho-3-sulfolactate synthase; (2R)-O-phospho-3-sulfolactate sulfo-lyase
Systematic name: (2R)-2-O-phospho-3-sulfolactate hydrogen-sulfite-lyase (phosphoenolpyruvate-forming)
Comments: Requires Mg2+. The enzyme from the archaeon Methanococcus jannaschii catalyses the Michael addition of sulfite to phosphoenolpyruvate. It specifically requires phosphoenolpyruvate and its broad alkaline pH optimum suggests that it uses sulfite rather than hydrogensulfite.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 473575-53-0
References:
1.  Graham, D.E., Xu, H. and White, R.H. Identification of coenzyme M biosynthetic phosphosulfolactate synthase: a new family of sulfonate-biosynthesizing enzymes. J. Biol. Chem. 277 (2002) 13421–13429. [DOI] [PMID: 11830598]
[EC 4.4.1.19 created 2003]
 
 
EC 4.4.1.23     
Accepted name: 2-hydroxypropyl-CoM lyase
Reaction: (1) (R)-2-hydroxypropyl-CoM = (R)-1,2-epoxypropane + HS-CoM
(2) (S)-2-hydroxypropyl-CoM = (S)-1,2-epoxypropane + HS-CoM
For diagram of epoxide carboxylation, click here
Glossary: coenzyme M (CoM) = 2-mercaptoethanesulfonate
Other name(s): epoxyalkane:coenzyme M transferase; epoxyalkane:CoM transferase; epoxyalkane:2-mercaptoethanesulfonate transferase; coenzyme M-epoxyalkane ligase; epoxyalkyl:CoM transferase; epoxypropane:coenzyme M transferase; epoxypropyl:CoM transferase; EaCoMT; 2-hydroxypropyl-CoM:2-mercaptoethanesulfonate lyase (epoxyalkane-ring-forming); (R)-2-hydroxypropyl-CoM 2-mercaptoethanesulfonate lyase (cyclizing; (R)-1,2-epoxypropane-forming)
Systematic name: (R)-[or (S)-]2-hydroxypropyl-CoM:2-mercaptoethanesulfonate lyase (epoxyalkane-ring-forming)
Comments: Requires zinc. Acts on both enantiomers of chiral epoxyalkanes to form the corresponding (R)- and (S)-2-hydroxyalkyl-CoM adducts. The enzyme will function with some other thiols (e.g., 2-sulfanylethanol) as the nucleophile. Uses short-chain epoxyalkanes from C2 (epoxyethane) to C6 (1,2-epoxyhexane). This enzyme forms component I of a four-component enzyme system {comprising EC 4.4.1.23 (2-hydroxypropyl-CoM lyase; component I), EC 1.8.1.5 [2-oxopropyl-CoM reductase (carboxylating); component II], EC 1.1.1.268 [2-(R)-hydroxypropyl-CoM dehydrogenase; component III] and EC 1.1.1.269 [2-(S)-hydroxypropyl-CoM dehydrogenase; component IV]} that is involved in epoxyalkane carboxylation in Xanthobacter sp. strain Py2.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, UM-BBD, CAS registry number: 244301-07-3
References:
1.  Allen, J.R., Clark, D.D., Krum, J.G. and Ensign, S.A. A role for coenzyme M (2-mercaptoethanesulfonic acid) in a bacterial pathway of aliphatic epoxide carboxylation. Proc. Natl. Acad. Sci. USA 96 (1999) 8432–8437. [DOI] [PMID: 10411892]
2.  Krum, J.G., Ellsworth, H., Sargeant, R.R., Rich, G. and Ensign, S.A. Kinetic and microcalorimetric analysis of substrate and cofactor interactions in epoxyalkane:CoM transferase, a zinc-dependent epoxidase. Biochemistry 41 (2002) 5005–5014. [DOI] [PMID: 11939797]
3.  Coleman, N.V. and Spain, J.C. Epoxyalkane: coenzyme M transferase in the ethene and vinyl chloride biodegradation pathways of Mycobacterium strain JS60. J. Bacteriol. 185 (2003) 5536–5545. [DOI] [PMID: 12949106]
[EC 4.4.1.23 created 2001 as EC 4.2.99.19, transferred 2005 to EC 4.4.1.23]
 
 


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