The Enzyme Database

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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 = CoB.html">coenzyme B = N-(7-sulfanylheptanoyl)threonine = N-(7-mercaptoheptanoyl)threonine 3-O-phosphate (deprecated)
CoM = coenzyme M = 2-sulfanylethane-1-sulfonate = 2-mercaptoethanesulfonate (deprecated)
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 = O3-phospho-N-{7-[2-(2-sulfoethyl)disulfan-1-yl]heptanoyl}-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, PDB
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-sulfanylheptanoyl)threonine = N-(7-mercaptoheptanoyl)threonine 3-O-phosphate (deprecated)
CoM = coenzyme M = 2-sulfanylethane-1-sulfonate = 2-mercaptoethanesulfonate (deprecated)
CoM-S-S-CoB = CoB-CoM heterodisulfide = N-{7-[(2-sulfoethyl)dithio]heptanoyl}-O3-phospho-L-threonine =
O3-phospho-N-{7-[2-(2-sulfoethyl)disulfan-1-yl]heptanoyl}-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-sulfanylheptanoyl)threonine = N-(7-mercaptoheptanoyl)threonine 3-O-phosphate (deprecated)
CoM = coenzyme M = 2-sulfanylethane-1-sulfonate = 2-mercaptoethanesulfonate (deprecated)
CoM-S-S-CoB = CoB-CoM heterodisulfide = N-{7-[(2-sulfoethyl)dithio]heptanoyl}-O3-phospho-L-threonine =
O3-phospho-N-{7-[2-(2-sulfoethyl)disulfan-1-yl]heptanoyl}-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: 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)
CoM-S-S-CoB = CoB-CoM heterodisulfide = N-{7-[(2-sulfoethyl)dithio]heptanoyl}-O3-phospho-L-threonine =
O3-phospho-N-{7-[2-(2-sulfoethyl)disulfan-1-yl]heptanoyl}-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 1.11.1.21     
Accepted name: catalase-peroxidase
Reaction: (1) donor + H2O2 = oxidized donor + 2 H2O
(2) 2 H2O2 = O2 + 2 H2O
Other name(s): katG (gene name)
Systematic name: donor:hydrogen-peroxide oxidoreductase
Comments: Differs from EC 1.11.1.7, peroxidase in having a relatively high catalase (EC 1.11.1.6) activity with H2O2 as donor, releasing O2; both activities use the same heme active site. In Mycobacterium tuberculosis it is responsible for activation of the commonly used antitubercular drug, isoniazid.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB
References:
1.  Loewen, P.C., Triggs, B.L., George, C.S. and Hrabarchuk, B.E. Genetic mapping of katG, a locus that affects synthesis of the bifunctional catalase-peroxidase hydroperoxidase I in Escherichia coli. J. Bacteriol. 162 (1985) 661–667. [PMID: 3886630]
2.  Hochman, A. and Goldberg, I. Purification and characterization of a catalase-peroxidase and a typical catalase from the bacterium Klebsiella pneumoniae. Biochim. Biophys. Acta 1077 (1991) 299–307. [DOI] [PMID: 2029529]
3.  Fraaije, M.W., Roubroeks, H.P., van Berkel, W.H.J. Purification and characterization of an intracellular catalase-peroxidase from Penicillium simplicissimum. Eur. J. Biochem. 235 (1996) 192–198. [PMID: 8631329]
4.  Bertrand, T., Eady, N.A., Jones, J.N., Jesmin, Nagy, J.M., Jamart-Gregoire, B., Raven, E.L. and Brown, K.A. Crystal structure of Mycobacterium tuberculosis catalase-peroxidase. J. Biol. Chem. 279 (2004) 38991–38999. [DOI] [PMID: 15231843]
5.  Vlasits, J., Jakopitsch, C., Bernroitner, M., Zamocky, M., Furtmuller, P.G. and Obinger, C. Mechanisms of catalase activity of heme peroxidases. Arch. Biochem. Biophys. 500 (2010) 74–81. [DOI] [PMID: 20434429]
[EC 1.11.1.21 created 2011]
 
 
EC 1.11.1.28     
Accepted name: lipoyl-dependent peroxiredoxin
Reaction: a [lipoyl-carrier protein]-N6-[(R)-dihydrolipoyl]-L-lysine + ROOH = a [lipoyl-carrier protein]-N6-[(R)-lipoyl]-L-lysine + H2O + ROH
For diagram of reaction, click here and for mechanism, click here
Other name(s): Ohr; ahpC (gene name); ahpD (gene name)
Systematic name: [lipoyl-carrier protein]-N6-[(R)-dihydrolipoyl]-L-lysine:hydroperoxide oxidoreductase
Comments: Peroxiredoxins (Prxs) are a ubiquitous family of antioxidant proteins. They can be divided into three classes: typical 2-Cys, atypical 2-Cys and 1-Cys peroxiredoxins [2]. The peroxidase reaction comprises two steps centred around a redox-active cysteine called the peroxidatic cysteine. All three peroxiredoxin classes have the first step in common, in which the peroxidatic cysteine attacks the peroxide substrate and is oxidized to S-hydroxycysteine (a sulfenic acid) (see mechanism). The second step of the peroxidase reaction, the regeneration of cysteine from S-hydroxycysteine, distinguishes the three peroxiredoxin classes. For typical 2-Cys Prxs, in the second step, the peroxidatic S-hydroxycysteine from one subunit is attacked by the ‘resolving’ cysteine located in the C-terminus of the second subunit, to form an intersubunit disulfide bond, which is then reduced by one of several cell-specific thiol-containing reductants completing the catalytic cycle. In the atypical 2-Cys Prxs, both the peroxidatic cysteine and its resolving cysteine are in the same polypeptide, so their reaction forms an intrachain disulfide bond. The 1-Cys Prxs conserve only the peroxidatic cysteine, so its regeneration involves direct interaction with a reductant molecule. Two types of lipoyl-dependent peroxiredoxins have been reported from bacteria. One type is the AhpC/AhpD system, originally described from Mycobacterium tuberculosis. In that system, AhpC catalyses reduction of the substrate, resulting in an intramolecular disulfide. AhpD then forms an intermolecular disulfide crosslink with AhpC, reducing it back to active state. AhpD is reduced in turn by lipoylated proteins. The second type, which has been characterized in Xylella fastidiosa, consists of only one type of subunit, which interacts directly with lipoylated proteins.
Links to other databases: BRENDA, EAWAG-BBD, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 207137-51-7
References:
1.  Hillas, P.J., del Alba, F.S., Oyarzabal, J., Wilks, A. and Ortiz De Montellano, P.R. The AhpC and AhpD antioxidant defense system of Mycobacterium tuberculosis. J. Biol. Chem. 275 (2000) 18801–18809. [PMID: 10766746]
2.  Wood, Z.A., Schröder, E., Harris, J.R. and Poole, L.B. Structure, mechanism and regulation of peroxiredoxins. Trends Biochem. Sci. 28 (2003) 32–40. [DOI] [PMID: 12517450]
3.  Koshkin, A., Nunn, C.M., Djordjevic, S. and Ortiz de Montellano, P.R. The mechanism of Mycobacterium tuberculosis alkylhydroperoxidase AhpD as defined by mutagenesis, crystallography, and kinetics. J. Biol. Chem. 278 (2003) 29502–29508. [PMID: 12761216]
4.  Koshkin, A., Knudsen, G.M. and Ortiz De Montellano, P.R. Intermolecular interactions in the AhpC/AhpD antioxidant defense system of Mycobacterium tuberculosis. Arch. Biochem. Biophys. 427 (2004) 41–47. [PMID: 15178486]
5.  Shi, S. and Ehrt, S. Dihydrolipoamide acyltransferase is critical for Mycobacterium tuberculosis pathogenesis. Infect. Immun. 74 (2006) 56–63. [PMID: 16368957]
6.  Cussiol, J.R., Alegria, T.G., Szweda, L.I. and Netto, L.E. Ohr (organic hydroperoxide resistance protein) possesses a previously undescribed activity, lipoyl-dependent peroxidase. J. Biol. Chem. 285 (2010) 21943–21950. [PMID: 20463026]
[EC 1.11.1.28 created 1983 as EC 1.11.1.15, part transferred 2020 to EC 1.11.1.28]
 
 
EC 1.11.1.29     
Accepted name: mycoredoxin-dependent peroxiredoxin
Reaction: mycoredoxin + ROOH = mycoredoxin disulfide + H2O + ROH
For diagram of reaction, click here and for mechanism, click here
Other name(s): ahpE (gene name)
Systematic name: mycoredoxin:hydroperoxide oxidoreductase
Comments: Peroxiredoxins (Prxs) are a ubiquitous family of antioxidant proteins. They can be divided into three classes: typical 2-Cys, atypical 2-Cys and 1-Cys peroxiredoxins [1]. The peroxidase reaction comprises two steps centred around a redox-active cysteine called the peroxidatic cysteine. All three peroxiredoxin classes have the first step in common, in which the peroxidatic cysteine attacks the peroxide substrate and is oxidized to S-hydroxycysteine (a sulfenic acid) (see mechanism). The second step of the peroxidase reaction, the regeneration of cysteine from S-hydroxycysteine, distinguishes the three peroxiredoxin classes. For typical 2-Cys Prxs, in the second step, the peroxidatic S-hydroxycysteine from one subunit is attacked by the ‘resolving’ cysteine located in the C-terminus of the second subunit, to form an intersubunit disulfide bond, which is then reduced by one of several cell-specific thiol-containing reductants completing the catalytic cycle. In the atypical 2-Cys Prxs, both the peroxidatic cysteine and its resolving cysteine are in the same polypeptide, so their reaction forms an intrachain disulfide bond. The 1-Cys Prxs conserve only the peroxidatic cysteine, so its regeneration involves direct interaction with a reductant molecule. Mycoredoxin-dependent enzymes are found in Mycobacteria. Following the reduction of the substrate, the sulfenic acid derivative of the peroxidatic cysteine forms a protein mixed disulfide with the N-terminal cysteine of mycoredoxin, which is then reduced by the C-terminal cysteine of mycoredoxin, restoring the peroxiredoxin to active state and resulting in an intra-protein disulfide in mycoredoxin. The disulfide is eventually reduced by mycothiol.
Links to other databases: BRENDA, EAWAG-BBD, EXPASY, KEGG, MetaCyc, PDB
References:
1.  Wood, Z.A., Schröder, E., Harris, J.R. and Poole, L.B. Structure, mechanism and regulation of peroxiredoxins. Trends Biochem. Sci. 28 (2003) 32–40. [DOI] [PMID: 12517450]
2.  Hugo, M., Turell, L., Manta, B., Botti, H., Monteiro, G., Netto, L.E., Alvarez, B., Radi, R. and Trujillo, M. Thiol and sulfenic acid oxidation of AhpE, the one-cysteine peroxiredoxin from Mycobacterium tuberculosis: kinetics, acidity constants, and conformational dynamics. Biochemistry 48 (2009) 9416–9426. [PMID: 19737009]
3.  Hugo, M., Van Laer, K., Reyes, A.M., Vertommen, D., Messens, J., Radi, R. and Trujillo, M. Mycothiol/mycoredoxin 1-dependent reduction of the peroxiredoxin AhpE from Mycobacterium tuberculosis. J. Biol. Chem. 289 (2014) 5228–5239. [PMID: 24379404]
4.  Kumar, A., Balakrishna, A.M., Nartey, W., Manimekalai, M.SS. and Gruber, G. Redox chemistry of Mycobacterium tuberculosis alkylhydroperoxide reductase E (AhpE): Structural and mechanistic insight into a mycoredoxin-1 independent reductive pathway of AhpE via mycothiol. Free Radic. Biol. Med. 97 (2016) 588–601. [PMID: 27417938]
5.  Pedre, B., van Bergen, L.A., Pallo, A., Rosado, L.A., Dufe, V.T., Molle, I.V., Wahni, K., Erdogan, H., Alonso, M., Proft, F.D. and Messens, J. The active site architecture in peroxiredoxins: a case study on Mycobacterium tuberculosis AhpE. Chem. Commun. (Camb.) 52 (2016) 10293–10296. [PMID: 27471753]
[EC 1.11.1.29 created 1983 as EC 1.11.1.15, part transferred 2020 to EC 1.11.1.29]
 
 
EC 1.12.99.2      
Deleted entry:  coenzyme-M-7-mercaptoheptanoylthreonine-phosphate-heterodisulfide hydrogenase. Now shown to be two enzymes, EC 1.12.98.3, Methanosarcina-phenazine hydrogenase and EC 1.8.98.1, CoB—CoM heterodisulfide reductase
[EC 1.12.99.2 created 1992, deleted 2002]
 
 
EC 1.13.11.81     
Accepted name: 7,8-dihydroneopterin oxygenase
Reaction: 7,8-dihydroneopterin + O2 = 7,8-dihydroxanthopterin + formate + glycolaldehyde
For diagram of methanopterin biosynthesis (part 1), click here
Glossary: 7,8-dihydroneopterin = 2-amino-6-[(1S,2R)-1,2,3-trihydroxypropyl]-7,8-dihydropteridin-4(3H)-one
7,8-dihydroxanthopterin = 2-amino-3,5,7,8-tetrahydropteridin-4,6-dione
Systematic name: 7,8-dihydroneopterin:oxygen oxidoreductase
Comments: The enzyme from the bacterium Mycobacterium tuberculosis is multifunctional and also catalyses the epimerisation of the 2′-hydroxy group of 7,8-dihydroneopterin (EC 5.1.99.8, 7,8-dihydroneopterin epimerase) and the reaction of EC 4.1.2.25 (dihydroneopterin aldolase).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB
References:
1.  Czekster, C.M. and Blanchard, J.S. One substrate, five products: reactions catalyzed by the dihydroneopterin aldolase from Mycobacterium tuberculosis. J. Am. Chem. Soc. 134 (2012) 19758–19771. [DOI] [PMID: 23150985]
[EC 1.13.11.81 created 2015]
 
 
EC 1.13.12.4     
Accepted name: lactate 2-monooxygenase
Reaction: (S)-lactate + O2 = acetate + CO2 + H2O
Other name(s): lactate oxidative decarboxylase; lactate oxidase; lactic oxygenase; lactate oxygenase; lactic oxidase; L-lactate monooxygenase; lactate monooxygenase; L-lactate-2-monooxygenase
Systematic name: (S)-lactate:oxygen 2-oxidoreductase (decarboxylating)
Comments: A flavoprotein (FMN).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9028-72-2
References:
1.  Hayaishi, O. and Sutton, W.B. Enzymatic oxygen fixation into acetate concomitant with the enzymatic decarboxylation of L-lactate. J. Am. Chem. Soc. 79 (1957) 4809–4810.
2.  Sutton, W.B. Mechanism of action and crystalization of lactic oxidative decarboxylase from Mycobacterium phlei. J. Biol. Chem. 226 (1957) 395–405. [PMID: 13428772]
[EC 1.13.12.4 created 1961 as EC 1.1.3.2, transferred 1972 to EC 1.13.12.4]
 
 
EC 1.14.11.49     
Accepted name: uridine-5′-phosphate dioxygenase
Reaction: UMP + 2-oxoglutarate + O2 = 5′-dehydrouridine + succinate + CO2 + phosphate
For diagram of pyrimidine biosynthesis, click here
Glossary: 5′-dehydrouridine = uridine-5′-aldehyde
Other name(s): lipL (gene name)
Systematic name: UMP,2-oxoglutarate:oxygen oxidoreductase
Comments: The enzyme catalyses a net dephosphorylation and oxidation of UMP to generate 5′-dehydrouridine, the first intermediate in the biosynthesis of the unusual aminoribosyl moiety found in several C7-furanosyl nucleosides such as A-90289s, caprazamycins, liposidomycins, muraymycins and FR-900453. Requires Fe2+.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Yang, Z., Chi, X., Funabashi, M., Baba, S., Nonaka, K., Pahari, P., Unrine, J., Jacobsen, J.M., Elliott, G.I., Rohr, J. and Van Lanen, S.G. Characterization of LipL as a non-heme, Fe(II)-dependent α-ketoglutarate:UMP dioxygenase that generates uridine-5′-aldehyde during A-90289 biosynthesis. J. Biol. Chem. 286 (2011) 7885–7892. [DOI] [PMID: 21216959]
2.  Yang, Z., Unrine, J., Nonaka, K. and Van Lanen, S.G. Fe(II)-dependent, uridine-5′-monophosphate α-ketoglutarate dioxygenases in the synthesis of 5′-modified nucleosides. Methods Enzymol. 516 (2012) 153–168. [DOI] [PMID: 23034228]
[EC 1.14.11.49 created 2015]
 
 
EC 1.14.11.77     
Accepted name: alkyl sulfatase
Reaction: a primary alkyl sulfate ester + 2-oxoglutarate + O2 = an aldehyde + succinate + CO2 + sulfate
Other name(s): atsK (gene name); α-ketoglutarate-dependent sulfate ester dioxygenase; 2-oxoglutarate-dependent sulfate ester dioxygenase; type II alkyl sulfatase
Systematic name: primary alkyl sulfate ester, 2-oxoglutarate:oxygen oxidoreductase (sulfate-hydrolyzing)
Comments: Sulfatase enzymes are classified as type I, in which the key catalytic residue is 3-oxo-L-alanine, type II, which are non-heme iron-dependent dioxygenases, or type III, whose catalytic domain adopts a metallo-β-lactamase fold and binds two zinc ions as cofactors. The type II sulfatases oxidize the C-H bond of the carbon next to the sulfate ester, using 2-oxoglutarate and oxygen as substrates. The resulting hemiacetal sulfate ester collapses, liberating inorganic sulfate and an alkyl aldehyde along with carbon dioxide and succinate. The enzymes often desulfate a broad spectrum of linear and branched-chain sulfate esters. The enzyme from Pseudomonas putida acts on a range of medium-chain alkyl sulfate esters, with chain lengths ranging from C4 to C12. cf. sulfatase EC 3.1.6.1, arylsulfatase (type I), EC 3.1.6.21, linear primary-alkylsulfatase, and EC 3.1.6.22, branched primary-alkylsulfatase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Kahnert, A. and Kertesz, M.A. Characterization of a sulfur-regulated oxygenative alkylsulfatase from Pseudomonas putida S-313. J. Biol. Chem. 275 (2000) 31661–31667. [DOI] [PMID: 10913158]
2.  Muller, I., Kahnert, A., Pape, T., Sheldrick, G.M., Meyer-Klaucke, W., Dierks, T., Kertesz, M. and Uson, I. Crystal structure of the alkylsulfatase AtsK: insights into the catalytic mechanism of the Fe(II) α-ketoglutarate-dependent dioxygenase superfamily. Biochemistry 43 (2004) 3075–3088. [DOI] [PMID: 15023059]
3.  Sogi, K.M., Gartner, Z.J., Breidenbach, M.A., Appel, M.J., Schelle, M.W. and Bertozzi, C.R. Mycobacterium tuberculosis Rv3406 is a type II alkyl sulfatase capable of sulfate scavenging. PLoS One 8:e65080 (2013). [DOI] [PMID: 23762287]
[EC 1.14.11.77 created 2021]
 
 
EC 1.14.13.83     
Accepted name: precorrin-3B synthase
Reaction: precorrin-3A + NADH + H+ + O2 = precorrin-3B + NAD+ + H2O
For diagram of corrin biosynthesis (part 3), click here and for mechanism of reaction, click here
Other name(s): precorrin-3X synthase; CobG
Systematic name: precorrin-3A,NADH:oxygen oxidoreductase (20-hydroxylating)
Comments: An iron-sulfur protein. An oxygen atom from dioxygen is incorporated into the macrocycle at C-20. In the aerobic cobalamin biosythesis pathway, four enzymes are involved in the conversion of precorrin-3A to precorrin-6A. The first of the four steps is carried out by EC 1.14.13.83, precorrin-3B synthase (CobG), yielding precorrin-3B as the product. This is followed by three methylation reactions, which introduce a methyl group at C-17 (CobJ; EC 2.1.1.131), C-11 (CobM; EC 2.1.1.133) and C-1 (CobF; EC 2.1.1.152) of the macrocycle, giving rise to precorrin-4, precorrin-5 and precorrin-6A, respectively.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 152787-63-8
References:
1.  Debussche, L., Thibaut, D., Cameron, B., Crouzet, J. and Blanche, F. Biosynthesis of the corrin macrocycle of coenzyme B12 in Pseudomonas denitrificans. J. Bacteriol. 175 (1993) 7430–7440. [DOI] [PMID: 8226690]
2.  Scott, A.I., Roessner, C.A., Stolowich, N.J., Spencer, J.B., Min, C. and Ozaki, S.I. Biosynthesis of vitamin B12. Discovery of the enzymes for oxidative ring contraction and insertion of the fourth methyl group. FEBS Lett. 331 (1993) 105–108. [DOI] [PMID: 8405386]
3.  Warren, M.J., Raux, E., Schubert, H.L. and Escalante-Semerena, J.C. The biosynthesis of adenosylcobalamin (vitamin B12). Nat. Prod. Rep. 19 (2002) 390–412. [PMID: 12195810]
[EC 1.14.13.83 created 2004]
 
 
EC 1.14.13.101     
Accepted name: senecionine N-oxygenase
Reaction: senecionine + NADPH + H+ + O2 = senecionine N-oxide + NADP+ + H2O
Other name(s): senecionine monooxygenase (N-oxide-forming); SNO
Systematic name: senecionine,NADPH:oxygen oxidoreductase (N-oxide-forming)
Comments: A flavoprotein. NADH cannot replace NADPH. While pyrrolizidine alkaloids of the senecionine and monocrotaline types are generally good substrates (e.g. senecionine, retrorsine and monocrotaline), the enzyme does not use ester alkaloids lacking an hydroxy group at C-7 (e.g. supinine and phalaenopsine), 1,2-dihydro-alkaloids (e.g. sarracine) or unesterified necine bases (e.g. senkirkine) as substrates [1]. Senecionine N-oxide is used by insects as a chemical defense: senecionine N-oxide is non-toxic, but it is bioactivated to a toxic form by the action of cytochrome P-450 oxidase when absorbed by insectivores.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 220581-68-0
References:
1.  Lindigkeit, R., Biller, A., Buch, M., Schiebel, H.M., Boppre, M. and Hartmann, T. The two facies of pyrrolizidine alkaloids: the role of the tertiary amine and its N-oxide in chemical defense of insects with acquired plant alkaloids. Eur. J. Biochem. 245 (1997) 626–636. [DOI] [PMID: 9182998]
2.  Naumann, C., Hartmann, T. and Ober, D. Evolutionary recruitment of a flavin-dependent monooxygenase for the detoxification of host plant-acquired pyrrolizidine alkaloids in the alkaloid-defended arctiid moth Tyria jacobaeae. Proc. Natl. Acad. Sci. USA 99 (2002) 6085–6090. [DOI] [PMID: 11972041]
[EC 1.14.13.101 created 2006]
 
 
EC 1.14.13.141      
Transferred entry: cholest-4-en-3-one 26-monooxygenase [(25S)-3-oxocholest-4-en-26-oate forming]. Now EC 1.14.15.29, cholest-4-en-3-one 26-monooxygenase [(25S)-3-oxocholest-4-en-26-oate forming]..
[EC 1.14.13.141 created 2012, modified 2016, deleted 2018]
 
 
EC 1.14.13.142      
Transferred entry: 3-ketosteroid 9α-monooxygenase. Now EC 1.14.15.30, 3-ketosteroid 9α-monooxygenase
[EC 1.14.13.142 created 2012, deleted 2018]
 
 
EC 1.14.13.221      
Transferred entry: cholest-4-en-3-one 26-monooxygenase [(25R)-3-oxocholest-4-en-26-oate forming]. Now EC 1.14.15.28, cholest-4-en-3-one 26-monooxygenase [(25R)-3-oxocholest-4-en-26-oate forming]
[EC 1.14.13.221 created 2016, deleted 2018]
 
 
EC 1.14.13.227     
Accepted name: propane 2-monooxygenase
Reaction: propane + NADH + H+ + O2 = propan-2-ol + NAD+ + H2O
Glossary: propan-2-ol = isopropanol
Other name(s): prmABCD (gene names)
Systematic name: propane,NADH:oxygen oxidoreductase (2-hydroxylating)
Comments: The enzyme, characterized from several bacterial strains, is a multicomponent dinuclear iron monooxygenase that includes a hydroxylase, an NADH-dependent reductase, and a coupling protein. The enzyme has several additional activities, including acetone monooxygenase (acetol-forming) and phenol 4-monooxygenase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Kotani, T., Yamamoto, T., Yurimoto, H., Sakai, Y. and Kato, N. Propane monooxygenase and NAD+-dependent secondary alcohol dehydrogenase in propane metabolism by Gordonia sp. strain TY-5. J. Bacteriol. 185 (2003) 7120–7128. [DOI] [PMID: 14645271]
2.  Sharp, J.O., Sales, C.M., LeBlanc, J.C., Liu, J., Wood, T.K., Eltis, L.D., Mohn, W.W. and Alvarez-Cohen, L. An inducible propane monooxygenase is responsible for N-nitrosodimethylamine degradation by Rhodococcus sp. strain RHA1. Appl. Environ. Microbiol. 73 (2007) 6930–6938. [DOI] [PMID: 17873074]
3.  Furuya, T., Hirose, S., Osanai, H., Semba, H. and Kino, K. Identification of the monooxygenase gene clusters responsible for the regioselective oxidation of phenol to hydroquinone in mycobacteria. Appl. Environ. Microbiol. 77 (2011) 1214–1220. [DOI] [PMID: 21183637]
[EC 1.14.13.227 created 2016]
 
 
EC 1.14.13.247     
Accepted name: stachydrine N-demethylase
Reaction: L-proline betaine + NAD(P)H + H+ + O2 = N-methyl-L-proline + formaldehyde + NAD(P)+ + H2O
Other name(s): L-proline betaine N-demethylase; stc2 (gene name)
Systematic name: L-proline betaine,NAD(P)H:oxygen oxidoreductase (formaldehyde-forming)
Comments: The enzyme, characterized from the bacterium Sinorhizobium meliloti 1021, consists of three different types of subunits. The catalytic unit contains a Rieske [2Fe-2S] iron-sulfur cluster, and catalyses the monooxygenation of a methyl group. The resulting N-methoxyl group is unstable and decomposes spontaneously to form formaldehyde. The other subunits are involved in the transfer of electrons from NAD(P)H to the catalytic subunit.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Daughtry, K.D., Xiao, Y., Stoner-Ma, D., Cho, E., Orville, A.M., Liu, P. and Allen, K.N. Quaternary ammonium oxidative demethylation: X-ray crystallographic, resonance Raman, and UV-visible spectroscopic analysis of a Rieske-type demethylase. J. Am. Chem. Soc. 134 (2012) 2823–2834. [PMID: 22224443]
2.  Kumar, R., Zhao, S., Vetting, M.W., Wood, B.M., Sakai, A., Cho, K., Solbiati, J., Almo, S.C., Sweedler, J.V., Jacobson, M.P., Gerlt, J.A. and Cronan, J.E. Prediction and biochemical demonstration of a catabolic pathway for the osmoprotectant proline betaine. MBio 5 (2014) e00933. [DOI] [PMID: 24520058]
[EC 1.14.13.247 created 2017]
 
 
EC 1.14.14.1     
Accepted name: unspecific monooxygenase
Reaction: RH + [reduced NADPH—hemoprotein reductase] + O2 = ROH + [oxidized NADPH—hemoprotein reductase] + H2O
Other name(s): microsomal monooxygenase; xenobiotic monooxygenase; aryl-4-monooxygenase; aryl hydrocarbon hydroxylase; microsomal P-450; flavoprotein-linked monooxygenase; flavoprotein monooxygenase; substrate,reduced-flavoprotein:oxygen oxidoreductase (RH-hydroxylating or -epoxidizing)
Systematic name: substrate,NADPH—hemoprotein reductase:oxygen oxidoreductase (RH-hydroxylating or -epoxidizing)
Comments: A group of P-450 heme-thiolate proteins, acting on a wide range of substrates including many xenobiotics, steroids, fatty acids, vitamins and prostaglandins; reactions catalysed include hydroxylation, epoxidation, N-oxidation, sulfooxidation, N-, S- and O-dealkylations, desulfation, deamination, and reduction of azo, nitro and N-oxide groups. Together with EC 1.6.2.4, NADPH—hemoprotein reductase, it forms a system in which two reducing equivalents are supplied by NADPH. Some of the reactions attributed to EC 1.14.15.3, alkane 1-monooxygenase, belong here.
Links to other databases: BRENDA, EAWAG-BBD, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9038-14-6
References:
1.  Booth, J. and Boyland, E. The biochemistry of aromatic amines. 3. Enzymic hydroxylation by rat-liver microsomes. Biochem. J. 66 (1957) 73–78. [PMID: 13426111]
2.  Fujita, T. and Mannering, G.J. Differences in soluble P-450 hemoproteins from livers of rats treated with phenobarbital and 3-methylcholanthrene. Chem. Biol. Interact. 3 (1971) 264–265. [DOI] [PMID: 5132997]
3.  Haugen, D.A. and Coon, M.J. Properties of electrophoretically homogeneous phenobarbital-inducible and β-naphthoflavone-inducible forms of liver microsomal cytochrome P-450. J. Biol. Chem. 251 (1976) 7929–7939. [PMID: 187601]
4.  Imaoka, S., Inoue, K. and Funae, Y. Aminopyrine metabolism by multiple forms of cytochrome P-450 from rat liver microsomes: simultaneous quantitation of four aminopyrine metabolites by high-performance liquid chromatography. Arch. Biochem. Biophys. 265 (1988) 159–170. [DOI] [PMID: 3415241]
5.  Johnson, E.F., Zounes, M. and Müller-Eberhard, U. Characterization of three forms of rabbit microsomal cytochrome P-450 by peptide mapping utilizing limited proteolysis in sodium dodecyl sulfate and analysis by gel electrophoresis. Arch. Biochem. Biophys. 192 (1979) 282–289. [DOI] [PMID: 434823]
6.  Kupfer, D., Miranda, G.K., Navarro, J., Piccolo, D.E. and Theoharides, A.D. Effect of inducers and inhibitors of monooxygenase on the hydroxylation of prostaglandins in the guinea pig. Evidence for several monooxygenases catalyzing ω- and ω-1-hydroxylation. J. Biol. Chem. 254 (1979) 10405–10414. [PMID: 489601]
7.  Lang, M.A., Gielen, J.E. and Nebert, D.W. Genetic evidence for many unique liver microsomal P-450-mediated monooxygenase activities in heterogeneic stock mice. J. Biol. Chem. 256 (1981) 12068–12075. [PMID: 7298645]
8.  Lang, M.A. and Nebert, D.W. Structural gene products of the Ah locus. Evidence for many unique P-450-mediated monooxygenase activities reconstituted from 3-methylcholanthrene-treated C57BL/6N mouse liver microsomes. J. Biol. Chem. 256 (1981) 12058–12075. [PMID: 7298644]
9.  Leo, M.A., Lasker, J.M., Rauby, J.L., Kim, C.I., Black, M. and Lieber, C.S. Metabolism of retinol and retinoic acid by human liver cytochrome P450IIC8. Arch. Biochem. Biophys. 269 (1989) 305–312. [DOI] [PMID: 2916844]
10.  Lu, A.Y.H., Kuntzman, S.W., Jacobson, M. and Conney, A.H. Reconstituted liver microsomal enzyme system that hydroxylates drugs, other foreign compounds, and endogenous substrates. II. Role of the cytochrome P-450 and P-448 fractions in drug and steroid hydroxylations. J. Biol. Chem. 247 (1972) 1727–1734. [PMID: 4401153]
11.  Mitoma, C., Posner, H.S., Reitz, H.C. and Udenfriend, S. Enzymic hydroxylation of aromatic compounds. Arch. Biochem. Biophys. 61 (1956) 431–441. [DOI] [PMID: 13314626]
12.  Mitoma, C. and Udenfriend, S. Aryl-4-hydroxylase. Methods Enzymol. 5 (1962) 816–819.
13.  Napoli, J.L., Okita, R.T., Masters, B.S. and Horst, R.L. Identification of 25,26-dihydroxyvitamin D3 as a rat renal 25-hydroxyvitamin D3 metabolite. Biochemistry 20 (1981) 5865–5871. [PMID: 7295706]
14.  Nebert, D.W. and Gelboin, H.V. Substrate-inducible microsomal aryl hydroxylase in mammalian cell culture. I. Assay and properties of induced enzyme. J. Biol. Chem. 243 (1968) 6242–6249. [PMID: 4387094]
15.  Suhara, K., Ohashi, K., Takahashi, K. and Katagiri, M. Aromatase and nonaromatizing 10-demethylase activity of adrenal cortex mitochondrial P-450(11)beta. Arch. Biochem. Biophys. 267 (1988) 31–37. [DOI] [PMID: 3264134]
16.  Theoharides, A.D. and Kupfer, D. Evidence for different hepatic microsomal monooxygenases catalyzing ω- and (ω-1)-hydroxylations of prostaglandins E1 and E2. Effects of inducers of monooxygenase on the kinetic constants of prostaglandin hydroxylation. J. Biol. Chem. 256 (1981) 2168–2175. [PMID: 7462235]
17.  Thomas, P.E., Lu, A.Y.H., Ryan, D., West, S.B., Kawalek, J. and Levin, W. Immunochemical evidence for six forms of rat liver cytochrome P450 obtained using antibodies against purified rat liver cytochromes P450 and P448. Mol. Pharmacol. 12 (1976) 746–758. [PMID: 825720]
[EC 1.14.14.1 created 1961 as EC 1.99.1.1, transferred 1965 to EC 1.14.1.1, transferred 1972 to EC 1.14.14.1 (EC 1.14.14.2 created 1972, incorporated 1976, EC 1.14.99.8 created 1972, incorporated 1984), modified 2015]
 
 
EC 1.14.14.12     
Accepted name: 3-hydroxy-9,10-secoandrosta-1,3,5(10)-triene-9,17-dione monooxygenase
Reaction: 3-hydroxy-9,10-secoandrosta-1,3,5(10)-triene-9,17-dione + FMNH2 + O2 = 3,4-dihydroxy-9,10-secoandrosta-1,3,5(10)-triene-9,17-dione + FMN + H2O
Other name(s): HsaA
Systematic name: 3-hydroxy-9,10-secoandrosta-1,3,5(10)-triene-9,17-dione,FMNH2:oxygen oxidoreductase
Comments: This bacterial enzyme participates in the degradation of several steroids, including cholesterol and testosterone. It can use either FADH or FMNH2 as flavin cofactor. The enzyme forms a two-component system with a reductase (HsaB) that utilizes NADH to reduce the flavin, which is then transferred to the oxygenase subunit.
Links to other databases: BRENDA, EAWAG-BBD, EXPASY, KEGG, MetaCyc, PDB
References:
1.  Dresen, C., Lin, L.Y., D'Angelo, I., Tocheva, E.I., Strynadka, N. and Eltis, L.D. A flavin-dependent monooxygenase from Mycobacterium tuberculosis involved in cholesterol catabolism. J. Biol. Chem. 285 (2010) 22264–22275. [DOI] [PMID: 20448045]
[EC 1.14.14.12 created 2011]
 
 
EC 1.14.15.14     
Accepted name: methyl-branched lipid ω-hydroxylase
Reaction: a methyl-branched lipid + O2 + 2 reduced ferredoxin [iron-sulfur] cluster + 2 H+ = an ω-hydroxy-methyl-branched lipid + H2O + 2 oxidized ferredoxin [iron-sulfur] cluster
Other name(s): CYP124
Systematic name: methyl-branched lipid,reduced-ferredoxin:oxygen oxidoreductase (ω-hydroxylating)
Comments: The enzyme, found in pathogenic and nonpathogenic mycobacteria species, actinomycetes, and some proteobacteria, hydroxylates the ω-carbon of a number of methyl-branched lipids, including (2E,6E)-farnesol, phytanate, geranylgeraniol, 15-methylpalmitate and (2E,6E)-farnesyl diphosphate. It is a P-450 heme-thiolate enzyme.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB
References:
1.  Johnston, J.B., Kells, P.M., Podust, L.M. and Ortiz de Montellano, P.R. Biochemical and structural characterization of CYP124: a methyl-branched lipid ω-hydroxylase from Mycobacterium tuberculosis. Proc. Natl. Acad. Sci. USA 106 (2009) 20687–20692. [DOI] [PMID: 19933331]
[EC 1.14.15.14 created 2015]
 
 
EC 1.14.15.27     
Accepted name: β-dihydromenaquinone-9 ω-hydroxylase
Reaction: β-dihydromenaquinone-9 + 2 reduced ferredoxin [iron-sulfur] cluster + O2 = ω-hydroxy-β-dihydromenaquinone-9 + 2 oxidized ferredoxin [iron-sulfur] cluster + H2O
For diagram of vitamin K biosynthesis, click here
Glossary: β-dihydromenaquinone-9 = MK-9(II-H2) = 2-methyl-3-[(2E,10E,14E,18E,22E,26E,30E,33E)-3,7,11,15,19,23,27,31,35-nonamethylhexatriaconta-2,10,14,18,22,26,30,33-octaen-1-yl]naphthalene-1,4-dione
Other name(s): cyp128 (gene name)
Systematic name: β-dihydromenaquinone-9,reduced ferredoxin:oxygen oxidoreductase (ω-hydroxylating)
Comments: The bacterial cytochrome P-450 enzyme is involved in the biosynthesis of ω-sulfo-β-dihydromenaquinone-9 by members of the Mycobacterium tuberculosis complex.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Holsclaw, C.M., Sogi, K.M., Gilmore, S.A., Schelle, M.W., Leavell, M.D., Bertozzi, C.R. and Leary, J.A. Structural characterization of a novel sulfated menaquinone produced by stf3 from Mycobacterium tuberculosis. ACS Chem. Biol. 3 (2008) 619–624. [PMID: 18928249]
2.  Sogi, K.M., Holsclaw, C.M., Fragiadakis, G.K., Nomura, D.K., Leary, J.A. and Bertozzi, C.R. Biosynthesis and regulation of sulfomenaquinone, a metabolite associated with virulence in Mycobacterium tuberculosis. ACS Infect Dis 2 (2016) 800–806. [PMID: 27933784]
[EC 1.14.15.27 created 2018]
 
 
EC 1.14.15.28     
Accepted name: cholest-4-en-3-one 26-monooxygenase [(25R)-3-oxocholest-4-en-26-oate forming]
Reaction: cholest-4-en-3-one + 6 reduced [2Fe-2S] ferredoxin + 3 O2 = (25R)-3-oxocholest-4-en-26-oate + 6 oxidized [2Fe-2S] ferredoxin + 4 H2O (overall reaction)
(1a) cholest-4-en-3-one + 2 reduced [2Fe-2S] ferredoxin + O2 = (25R)-26-hydroxycholest-4-en-3-one + 2 oxidized [2Fe-2S] ferredoxin + H2O
(1b) (25R)-26-hydroxycholest-4-en-3-one + 2 reduced [2Fe-2S] ferredoxin + O2 = (25R)-26-oxocholest-4-en-3-one + 2 oxidized [2Fe-2S] ferredoxin + 2 H2O
(1c) (25R)-26-oxocholest-4-en-3-one + 2 reduced [2Fe-2S] ferredoxin + O2 = (25R)-3-oxocholest-4-en-26-oate + 2 oxidized [2Fe-2S] ferredoxin + H2O
Other name(s): CYP142
Systematic name: cholest-4-en-3-one,reduced [2Fe-2S] ferredoxin:oxygen oxidoreductase [(25R)-3-oxocholest-4-en-26-oate-forming]
Comments: This cytochrome P-450 (heme-thiolate) enzyme, found in several bacterial pathogens, is involved in degradation of the host cholesterol. It catalyses the hydroxylation of the C-26 carbon, followed by oxidation of the alcohol to the carboxylic acid via the aldehyde intermediate, initiating the degradation of the alkyl side-chain of cholesterol. The products are exclusively in the (25R) conformation. The enzyme also accepts cholesterol as a substrate. cf. EC 1.14.15.29, cholest-4-en-3-one 26-monooxygenase [(25S)-3-oxocholest-4-en-26-oate forming]. The enzyme can receive electrons from ferredoxin reductase in vitro, its natural electron donor is not known yet.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB
References:
1.  Driscoll, M.D., McLean, K.J., Levy, C., Mast, N., Pikuleva, I.A., Lafite, P., Rigby, S.E., Leys, D. and Munro, A.W. Structural and biochemical characterization of Mycobacterium tuberculosis CYP142: evidence for multiple cholesterol 27-hydroxylase activities in a human pathogen. J. Biol. Chem. 285 (2010) 38270–38282. [DOI] [PMID: 20889498]
2.  Johnston, J.B., Ouellet, H. and Ortiz de Montellano, P.R. Functional redundancy of steroid C26-monooxygenase activity in Mycobacterium tuberculosis revealed by biochemical and genetic analyses. J. Biol. Chem. 285 (2010) 36352–36360. [DOI] [PMID: 20843794]
[EC 1.14.15.28 created 2016 as EC 1.14.13.221, transferred 2018 to EC 1.14.15.28]
 
 
EC 1.14.15.29     
Accepted name: cholest-4-en-3-one 26-monooxygenase [(25S)-3-oxocholest-4-en-26-oate forming]
Reaction: cholest-4-en-3-one + 6 reduced ferredoxin [iron-sulfur] cluster + 6 H+ + 3 O2 = (25S)-3-oxocholest-4-en-26-oate + 6 oxidized ferredoxin [iron-sulfur] cluster + 4 H2O (overall reaction)
(1a) cholest-4-en-3-one + 2 reduced ferredoxin [iron-sulfur] cluster + 2 H+ + O2 = (25S)-26-hydroxycholest-4-en-3-one + 2 oxidized ferredoxin [iron-sulfur] cluster + H2O
(1b) (25S)-26-hydroxycholest-4-en-3-one + 2 reduced ferredoxin [iron-sulfur] cluster + 2 H+ + O2 = (25S)-26-oxocholest-4-en-3-one + 2 oxidized ferredoxin [iron-sulfur] cluster + 2 H2O
(1c) (25S)-26-oxocholest-4-en-3-one + 2 reduced ferredoxin [iron-sulfur] cluster + 2 H+ + O2 = (25S)-3-oxocholest-4-en-26-oate + 2 oxidized ferredoxin [iron-sulfur] cluster + H2O
Other name(s): CYP125; CYP125A1; cholest-4-en-3-one 27-monooxygenase (misleading); cholest-4-en-3-one,NADH:oxygen oxidoreductase (26-hydroxylating); cholest-4-en-3-one 26-monooxygenase (ambiguous)
Systematic name: cholest-4-en-3-one,[reduced ferredoxin]:oxygen oxidoreductase [(25S)-3-oxocholest-4-en-26-oate-forming]
Comments: A cytochrome P-450 (heme-thiolate) protein found in several bacterial pathogens. The enzyme is involved in degradation of the host's cholesterol. It catalyses the hydroxylation of the C-26 carbon, followed by oxidation of the alcohol to the carboxylic acid via the aldehyde intermediate, initiating the degradation of the alkyl side-chain of cholesterol [4]. The products are exclusively in the (25S) configuration. The enzyme is part of a two-component system that also includes a ferredoxin reductase (most likely KshB, which also interacts with EC 1.14.15.30, 3-ketosteroid 9α-monooxygenase). The enzyme also accepts cholesterol as a substrate. cf. EC 1.14.15.28, cholest-4-en-3-one 27-monooxygenase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB
References:
1.  Rosloniec, K.Z., Wilbrink, M.H., Capyk, J.K., Mohn, W.W., Ostendorf, M., van der Geize, R., Dijkhuizen, L. and Eltis, L.D. Cytochrome P450 125 (CYP125) catalyses C26-hydroxylation to initiate sterol side-chain degradation in Rhodococcus jostii RHA1. Mol. Microbiol. 74 (2009) 1031–1043. [DOI] [PMID: 19843222]
2.  McLean, K.J., Lafite, P., Levy, C., Cheesman, M.R., Mast, N., Pikuleva, I.A., Leys, D. and Munro, A.W. The Structure of Mycobacterium tuberculosis CYP125: molecular basis for cholesterol binding in a P450 needed for host infection. J. Biol. Chem. 284 (2009) 35524–35533. [DOI] [PMID: 19846552]
3.  Capyk, J.K., Kalscheuer, R., Stewart, G.R., Liu, J., Kwon, H., Zhao, R., Okamoto, S., Jacobs, W.R., Jr., Eltis, L.D. and Mohn, W.W. Mycobacterial cytochrome P450 125 (Cyp125) catalyzes the terminal hydroxylation of C27 steroids. J. Biol. Chem. 284 (2009) 35534–35542. [DOI] [PMID: 19846551]
4.  Ouellet, H., Guan, S., Johnston, J.B., Chow, E.D., Kells, P.M., Burlingame, A.L., Cox, J.S., Podust, L.M. and de Montellano, P.R. Mycobacterium tuberculosis CYP125A1, a steroid C27 monooxygenase that detoxifies intracellularly generated cholest-4-en-3-one. Mol. Microbiol. 77 (2010) 730–742. [DOI] [PMID: 20545858]
[EC 1.14.15.29 created 2012 as EC 1.14.13.141, modified 2016, transferred 2018 to EC 1.14.15.29]
 
 
EC 1.14.15.30     
Accepted name: 3-ketosteroid 9α-monooxygenase
Reaction: androsta-1,4-diene-3,17-dione + 2 reduced ferredoxin [iron-sulfur] cluster + 2 H+ + O2 = 9α-hydroxyandrosta-1,4-diene-3,17-dione + 2 oxidized ferredoxin [iron-sulfur] cluster + H2O
Other name(s): KshA; 3-ketosteroid 9α-hydroxylase
Systematic name: androsta-1,4-diene-3,17-dione,[reduced ferredoxin]:oxygen oxidoreductase (9α-hydroxylating)
Comments: The enzyme is involved in the cholesterol degradation pathway of several bacterial pathogens, such as Mycobacterium tuberculosis. It forms a two-component system with a ferredoxin reductase (KshB). The enzyme contains a Rieske-type iron-sulfur center and non-heme iron. The product of the enzyme is unstable, and spontaneously converts to 3-hydroxy-9,10-seconandrost-1,3,5(10)-triene-9,17-dione.
Links to other databases: BRENDA, EAWAG-BBD, EXPASY, KEGG, MetaCyc, PDB
References:
1.  Petrusma, M., Dijkhuizen, L. and van der Geize, R. Rhodococcus rhodochrous DSM 43269 3-ketosteroid 9α-hydroxylase, a two-component iron-sulfur-containing monooxygenase with subtle steroid substrate specificity. Appl. Environ. Microbiol. 75 (2009) 5300–5307. [DOI] [PMID: 19561185]
2.  Capyk, J.K., D'Angelo, I., Strynadka, N.C. and Eltis, L.D. Characterization of 3-ketosteroid 9α-hydroxylase, a Rieske oxygenase in the cholesterol degradation pathway of Mycobacterium tuberculosis. J. Biol. Chem. 284 (2009) 9937–9946. [DOI] [PMID: 19234303]
3.  Capyk, J.K., Casabon, I., Gruninger, R., Strynadka, N.C. and Eltis, L.D. Activity of 3-ketosteroid 9α-hydroxylase (KshAB) indicates cholesterol side chain and ring degradation occur simultaneously in Mycobacterium tuberculosis. J. Biol. Chem. 286 (2011) 40717–40724. [DOI] [PMID: 21987574]
[EC 1.14.15.30 created 2012 as EC 1.14.13.142, transferred 2018 to EC 1.14.15.30]
 
 
EC 1.14.19.1     
Accepted name: stearoyl-CoA 9-desaturase
Reaction: stearoyl-CoA + 2 ferrocytochrome b5 + O2 + 2 H+ = oleoyl-CoA + 2 ferricytochrome b5 + 2 H2O
Other name(s): Δ9-desaturase; acyl-CoA desaturase; fatty acid desaturase; stearoyl-CoA, hydrogen-donor:oxygen oxidoreductase
Systematic name: stearoyl-CoA,ferrocytochrome-b5:oxygen oxidoreductase (9,10-dehydrogenating)
Comments: An iron protein. The rat liver enzyme is an enzyme system involving cytochrome b5 and EC 1.6.2.2, cytochrome-b5 reductase. The ferricytochrome b5 produced is reduced by NADH and cytochrome-b5 reductase (EC 1.6.2.2).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9014-34-0
References:
1.  Fulco, A.J. and Bloch, K. Cofactor requirements for the formation of Δ9-unsaturated fatty acids in Mycobacterium phlei. J. Biol. Chem. 239 (1964) 993–997. [PMID: 14167617]
2.  Oshino, N., Imai, Y. and Sato, R. Electron-transfer mechanism associated with fatty acid desaturation catalyzed by liver microsomes. Biochim. Biophys. Acta 128 (1966) 13–27. [PMID: 4382040]
3.  Oshino, N., Imai, Y. and Sato, R. A function of cytochrome b5 in fatty acid desaturation by rat liver microsomes. J. Biochem. (Tokyo) 69 (1971) 155–167. [PMID: 5543646]
4.  Strittmatter, P., Sputz, L., Corcoran, D., Rogers, M.J., Setlow, B. and Redline, R. Purification and properties of rat liver microsomal stearyl coenzyme A desaturase. Proc. Natl. Acad. Sci. USA 71 (1974) 4565–4569. [DOI] [PMID: 4373719]
[EC 1.14.19.1 created 1972 as EC 1.14.99.5, modified 1986, modified 2000, transferred 2000 to EC 1.14.19.1, modified 2003]
 
 
EC 1.14.19.70     
Accepted name: mycocyclosin synthase
Reaction: cyclo(L-tyrosyl-L-tyrosyl) + 2 reduced ferredoxin [iron-sulfur] cluster + 2 H+ + O2 = mycocyclosin + 2 oxidized ferredoxin [iron-sulfur] cluster + 2 H2O
For diagram of cyclic dipeptide biosynthesis, click here
Glossary: mycocyclosin = (1S,14S)-6,9-dihydroxy-15,17-diazatetracyclo[12.2.2.13,7.18,12]icosa-3(20),4,6,8(19),9,11-hexaene-16,18-dione
Other name(s): CYP121; rv2276 (locus name)
Systematic name: cyclo(L-tyrosyl-L-tyrosyl),reduced ferredoxin:oxygen oxidoreductase (diarylbridge-forming)
Comments: A cytochrome P-450 (heme-thiolate) protein from the bacterium Mycobacterium tuberculosis catalysing an oxidative reaction that does not incorporate oxygen into the product.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB
References:
1.  Belin, P., Le Du, M.H., Fielding, A., Lequin, O., Jacquet, M., Charbonnier, J.B., Lecoq, A., Thai, R., Courcon, M., Masson, C., Dugave, C., Genet, R., Pernodet, J.L. and Gondry, M. Identification and structural basis of the reaction catalyzed by CYP121, an essential cytochrome P450 in Mycobacterium tuberculosis. Proc. Natl. Acad. Sci. USA 106 (2009) 7426–7431. [DOI] [PMID: 19416919]
[EC 1.14.19.70 created 2013 as EC 1.14.21.9, transferred 2018 to EC 1.14.19.70]
 
 
EC 1.14.21.9      
Transferred entry: mycocyclosin synthase. Now EC 1.14.19.70, mycocyclosin synthase
[EC 1.14.21.9 created 2013, deleted 2018]
 
 
EC 1.14.99.50     
Accepted name: γ-glutamyl hercynylcysteine S-oxide synthase
Reaction: hercynine + γ-L-glutamyl-L-cysteine + O2 = γ-L-glutamyl-S-(hercyn-2-yl)-L-cysteine S-oxide + H2O
For diagram of ergothioneine and ovothiol biosynthesis, click here
Glossary: hercynine = Nα,Nα,Nα-trimethyl-L-histidine
Other name(s): EgtB
Systematic name: hercynine,γ-L-glutamyl-L-cysteine:oxygen oxidoreductase [γ-L-glutamyl-S-(hercyn-2-yl)-L-cysteine S-oxide-forming]
Comments: Requires Fe2+ for activity. The enzyme, found in bacteria, is specific for both hercynine and γ-L-glutamyl-L-cysteine. It is part of the biosynthesis pathway of ergothioneine.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB
References:
1.  Seebeck, F.P. In vitro reconstitution of mycobacterial ergothioneine biosynthesis. J. Am. Chem. Soc. 132 (2010) 6632–6633. [DOI] [PMID: 20420449]
2.  Pluskal, T., Ueno, M. and Yanagida, M. Genetic and metabolomic dissection of the ergothioneine and selenoneine biosynthetic pathway in the fission yeast, S. pombe, and construction of an overproduction system. PLoS One 9:e97774 (2014). [DOI] [PMID: 24828577]
[EC 1.14.99.50 created 2015]
 
 
EC 1.14.99.57     
Accepted name: heme oxygenase (mycobilin-producing)
Reaction: (1) protoheme + 3 reduced acceptor + 3 O2 = mycobilin a + Fe2+ + 3 acceptor + 3 H2O
(2) protoheme + 3 reduced acceptor + 3 O2 = mycobilin b + Fe2+ + 3 acceptor + 3 H2O
For diagram of mycobilin biosynthesis, click here
Glossary: mycobilin a = 8,12-bis(2-carboxyethyl)-19-formyl-3,7,13,18-tetramethyl-3,17-divinylbiladiene-ab-1,15(21H)-dione
mycobilin b = 8,12-bis(2-carboxyethyl)-19-formyl-2,7,13,17-tetramethyl-3,18-divinylbiladiene-ab-1,15(21H)-dione
Other name(s): mhuD (gene name)
Systematic name: protoheme,donor:oxygen oxidoreductase (mycobilin-producing)
Comments: The enzyme, characterized from the bacterium Mycobacterium tuberculosis, is involved in heme degradation and iron utilization. The enzyme binds two stacked protoheme molecules per monomer. Unlike the canonical heme oxygenases, the enzyme does not release carbon monoxide or formaldehyde. Instead, it forms unique products, named mycobilins, that retain the α-meso-carbon at the ring cleavage site as an aldehyde group. EC 1.6.2.4, NADPH-hemoprotein reductase, can act as electron donor in vitro.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB
References:
1.  Chim, N., Iniguez, A., Nguyen, T.Q. and Goulding, C.W. Unusual diheme conformation of the heme-degrading protein from Mycobacterium tuberculosis. J. Mol. Biol. 395 (2010) 595–608. [DOI] [PMID: 19917297]
2.  Nambu, S., Matsui, T., Goulding, C.W., Takahashi, S. and Ikeda-Saito, M. A new way to degrade heme: the Mycobacterium tuberculosis enzyme MhuD catalyzes heme degradation without generating CO. J. Biol. Chem. 288 (2013) 10101–10109. [DOI] [PMID: 23420845]
3.  Graves, A.B., Morse, R.P., Chao, A., Iniguez, A., Goulding, C.W. and Liptak, M.D. Crystallographic and spectroscopic insights into heme degradation by Mycobacterium tuberculosis MhuD. Inorg. Chem. 53 (2014) 5931–5940. [DOI] [PMID: 24901029]
[EC 1.14.99.57 created 2017]
 
 
EC 1.16.1.3      
Deleted entry: aquacobalamin reductase. This entry has been deleted since no specific enzyme catalysing this activity has been identified and it has been shown that aquacobalamin is efficiently reduced by free dihydroflavins and by non-specific reduced flavoproteins.
[EC 1.16.1.3 created 1972 as EC 1.6.99.8, transferred 2002 to EC 1.16.1.3, modified 2020, deleted 2020]
 
 
EC 1.16.1.4      
Deleted entry: cob(II)alamin reductase. This entry has been deleted since no specific enzyme catalysing this activity has been identified and it has been shown that cob(II)alamin is efficiently reduced by free dihydroflavins and by non-specific reduced flavoproteins
[EC 1.16.1.4 created 1972 as EC 1.6.99.9, transferred 2002 to EC 1.16.1.4, deleted 2021]
 
 
EC 1.16.1.5      
Deleted entry: aquacobalamin reductase (NADPH). This entry has been deleted since the enzyme the entry was based on was later shown to be EC 1.2.1.51, pyruvate dehydrogenase (NADP+). On the other hand, it has been shown that non-enzymatic reduction of cob(III)alamin to cob(II)alamin occurs efficiently in the presence of free dihydroflavins or non-specific reduced flavoproteins.
[EC 1.16.1.5 created 1989 as EC 1.6.99.11, transferred 2002 to EC 1.16.1.5, modified 2020, deleted 2020]
 
 
EC 1.16.1.6     
Accepted name: cyanocobalamin reductase
Reaction: 2 cob(II)alamin-[cyanocobalamin reductase] + 2 hydrogen cyanide + NADP+ = 2 cyanocob(III)alamin + 2 [cyanocobalamin reductase] + NADPH + H+
Other name(s): MMACHC (gene name); CblC; cyanocobalamin reductase (NADPH, cyanide-eliminating); cyanocobalamin reductase (NADPH, CN-eliminating); NADPH:cyanocob(III)alamin oxidoreductase (cyanide-eliminating); cob(I)alamin, cyanide:NADP+ oxidoreductase; cyanocobalamin reductase (cyanide-eliminating)
Systematic name: cob(II)alamin, hydrogen cyanide:NADP+ oxidoreductase
Comments: The mammalian enzyme, which is cytosolic, can bind internalized cyanocobalamin and process it to cob(II)alamin by removing the upper axial ligand. The product remains bound to the protein, which, together with its interacting partner MMADHC, transfers it directly to downstream enzymes involved in adenosylcobalamin and methylcobalamin biosynthesis. In addition to its decyanase function, the mammalian enzyme also catalyses an entirely different chemical reaction with alkylcobalamins, using the thiolate of glutathione for nucleophilic displacement, generating cob(I)alamin and the corresponding glutathione thioether (cf. EC 2.5.1.151, alkylcobalamin dealkylase).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 131145-00-1
References:
1.  Watanabe, F., Oki, Y., Nakano, Y. and Kitaoka, S. Occurrence and characterization of cyanocobalamin reductase (NADPH; CN-eliminating) involved in decyanation of cyanocobalamin in Euglena gracilis. J. Nutr. Sci. Vitaminol. 34 (1988) 1–10. [PMID: 3134526]
2.  Kim, J., Gherasim, C. and Banerjee, R. Decyanation of vitamin B12 by a trafficking chaperone. Proc. Natl. Acad. Sci. USA 105 (2008) 14551–14554. [PMID: 18779575]
3.  Koutmos, M., Gherasim, C., Smith, J.L. and Banerjee, R. Structural basis of multifunctionality in a vitamin B12-processing enzyme. J. Biol. Chem. 286 (2011) 29780–29787. [PMID: 21697092]
4.  Mah, W., Deme, J.C., Watkins, D., Fung, S., Janer, A., Shoubridge, E.A., Rosenblatt, D.S. and Coulton, J.W. Subcellular location of MMACHC and MMADHC, two human proteins central to intracellular vitamin B12 metabolism. Mol Genet Metab 108 (2013) 112–118. [PMID: 23270877]
[EC 1.16.1.6 created 1989 as EC 1.6.99.12, transferred 2002 to EC 1.16.1.6, modified 2018, modified 2021]
 
 
EC 1.16.1.8     
Accepted name: [methionine synthase] reductase
Reaction: 2 [methionine synthase]-methylcob(III)alamin + 2 S-adenosyl-L-homocysteine + NADP+ = 2 [methionine synthase]-cob(II)alamin + NADPH + H+ + 2 S-adenosyl-L-methionine
For diagram of reaction, click here
Other name(s): methionine synthase cob(II)alamin reductase (methylating); methionine synthase reductase; [methionine synthase]-cobalamin methyltransferase (cob(II)alamin reducing); [methionine synthase]-methylcob(I)alamin,S-adenosylhomocysteine:NADP+ oxidoreductase
Systematic name: [methionine synthase]-methylcob(III)alamin,S-adenosyl-L-homocysteine:NADP+ oxidoreductase
Comments: In humans, the enzyme is a flavoprotein containing FAD and FMN. The substrate of the enzyme is the inactivated cobalt(II) form of EC 2.1.1.13, methionine synthase. Electrons are transferred from NADPH to FAD to FMN. Defects in this enzyme lead to hereditary hyperhomocysteinemia.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 207004-87-3
References:
1.  Leclerc, D., Wilson, A., Dumas, R., Gafuik, C., Song, D., Watkins, D., Heng, H.H.Q., Rommens, J.M., Scherer, S.W., Rosenblatt, D.S., Gravel, R.A. Cloning and mapping of a cDNA for methionine synthase reductase, a flavoprotein defective in patients with homocystinuria. Proc. Natl. Acad. Sci. USA 95 (1998) 3059–3064. [DOI] [PMID: 9501215]
2.  Olteanu, H. and Banerjee, R. Human methionine synthase reductase, a soluble P-450 reductase-like dual flavoprotein, is sufficient for NADPH-dependent methionine synthase activation. J. Biol. Chem. 276 (2001) 35558–35563. [DOI] [PMID: 11466310]
3.  Olteanu, H., Munson, T. and Banerjee, R. Differences in the efficiency of reductive activation of methionine synthase and exogenous electron acceptors between the common polymorphic variants of human methionine synthase reductase. Biochemistry 41 (2002) 13378–13385. [DOI] [PMID: 12416982]
[EC 1.16.1.8 created 1999 as EC 2.1.1.135, transferred 2003 to EC 1.16.1.8, modified 2020]
 
 
EC 1.16.8.1      
Deleted entry: cob(II)yrinic acid a,c-diamide reductase. This activity is now known to be catalyzed by EC 2.5.1.17, corrinoid adenosyltransferase
[EC 1.16.8.1 created 2004, deleted 2019]
 
 
EC 1.16.99.1     
Accepted name: [Co(II) methylated amine-specific corrinoid protein] reductase
Reaction: (1) ATP + a [Co(II) methylamine-specific corrinoid protein] + reduced acceptor + H2O = ADP + phosphate + a [Co(I) methylamine-specific corrinoid protein] + acceptor
(2) ATP + a [Co(II) dimethylamine-specific corrinoid protein] + reduced acceptor + H2O = ADP + phosphate + a [Co(I) dimethylamine-specific corrinoid protein] + acceptor
(3) ATP + a [Co(II) trimethylamine-specific corrinoid protein] + reduced acceptor + H2O = ADP + phosphate + a [Co(I) trimethylamine-specific corrinoid protein] + acceptor
Glossary: ramA (gene name)
Systematic name: acceptor:[cobalt(II) methylated amines-specific corrinoid protein] oxidoreductase (ATP-hydrolysing)
Comments: Methyltrophic corrinoid proteins must have the cobalt atom in the active cobalt(I) state to become methylated. Because the cobalt(I)/cobalt(II) transformation has a very low redox potential the corrinoid cofactor is subject to adventitious oxidation to the cobalt(II) state, which renders the proteins inactive. This enzyme, characterized from the methanogenic archaeon Methanosarcina barkeri, reduces cobalt(II) back to cobalt(I), restoring activity. The enzyme acts on the corrinoid proteins involved in methanogenesis from methylamine, dimethylamine, and trimethylamine, namely MtmC, MtbC, and MttC, respectively. While in vitro the enzyme can use Ti(III)-citrate as the electron donor, the in vivo donor is not known. The enzyme from Methanosarcina barkeri contains a C-terminal [4Fe-4S] ferredoxin-like domain.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Ferguson, T., Soares, J.A., Lienard, T., Gottschalk, G. and Krzycki, J.A. RamA, a protein required for reductive activation of corrinoid-dependent methylamine methyltransferase reactions in methanogenic archaea. J. Biol. Chem. 284 (2009) 2285–2295. [DOI] [PMID: 19043046]
2.  Durichen, H., Diekert, G. and Studenik, S. Redox potential changes during ATP-dependent corrinoid reduction determined by redox titrations with europium(II)-DTPA. Protein Sci. 28 (2019) 1902–1908. [DOI] [PMID: 31359509]
[EC 1.16.99.1 created 2021]
 
 
EC 1.17.4.1     
Accepted name: ribonucleoside-diphosphate reductase
Reaction: 2′-deoxyribonucleoside 5′-diphosphate + thioredoxin disulfide + H2O = ribonucleoside 5′-diphosphate + thioredoxin
Other name(s): ribonucleotide reductase (ambiguous); CDP reductase; ribonucleoside diphosphate reductase; UDP reductase; ADP reductase; nucleoside diphosphate reductase; ribonucleoside 5′-diphosphate reductase; ribonucleotide diphosphate reductase; 2′-deoxyribonucleoside-diphosphate:oxidized-thioredoxin 2′-oxidoreductase; RR; nrdB (gene name); nrdF (gene name); nrdJ (gene name)
Systematic name: 2′-deoxyribonucleoside-5′-diphosphate:thioredoxin-disulfide 2′-oxidoreductase
Comments: This enzyme is responsible for the de novo conversion of ribonucleoside diphosphates into deoxyribonucleoside diphosphates, which are essential for DNA synthesis and repair. There are three types of this enzyme differing in their cofactors. Class Ia enzymes contain a diiron(III)-tyrosyl radical, class Ib enzymes contain a dimanganese-tyrosyl radical, and class II enzymes contain adenosylcobalamin. In all cases the cofactors are involved in generation of a transient thiyl (sulfanyl) radical on a cysteine residue, which attacks the substrate, forming a ribonucleotide 3′-radical, followed by water loss to form a ketyl (α-oxoalkyl) radical. The ketyl radical is reduced to 3′-keto-deoxynucleotide concomitant with formation of a disulfide anion radical between two cysteine residues. A proton-coupled electron-transfer from the disulfide radical to the substrate generates a 3′-deoxynucleotide radical, and the final product is formed when the hydrogen atom that was initially removed from the 3′-position of the nucleotide by the thiyl radical is returned to the same position. The disulfide bridge is reduced by the action of thioredoxin. cf. EC 1.1.98.6, ribonucleoside-triphosphate reductase (formate) and EC 1.17.4.2, ribonucleoside-triphosphate reductase (thioredoxin).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9047-64-7
References:
1.  Larsson, A. and Reichard, P. Enzymatic synthesis of deoxyribonucleotides. IX. Allosteric effects in the reduction of pyrimidine ribonucleotides by the ribonucleoside diphosphate reductase system of Escherichia coli. J. Biol. Chem. 241 (1966) 2533–2539. [PMID: 5330119]
2.  Larsson, A. and Reichard, P. Enzymatic synthesis of deoxyribonucleotides. X. Reduction of purine ribonucleotides; allosteric behavior and substrate specificity of the enzyme system from Escherichia coli B. J. Biol. Chem. 241 (1966) 2540–2549. [PMID: 5330120]
3.  Moore, E.C. and Hurlbert, R.B. Regulation of mammalian deoxyribonucleotide biosynthesis by nucleotides as activators and inhibitors. J. Biol. Chem. 241 (1966) 4802–4809. [PMID: 5926184]
4.  Larsson, A. Ribonucleotide reductase from regenerating rat liver. II. Substrate phosphorylation level and effect of deoxyadenosine triphosphate. Biochim. Biophys. Acta 324 (1973) 447–451. [DOI] [PMID: 4543472]
5.  Lammers, M. and Follmann, H. The ribonucleotide reductases - a unique group of metalloenzymes essential for cell-proliferation. Struct. Bonding 54 (1983) 27–91.
6.  Stubbe, J., Ator, M. and Krenitsky, T. Mechanism of ribonucleoside diphosphate reductase from Escherichia coli. Evidence for 3′-C--H bond cleavage. J. Biol. Chem. 258 (1983) 1625–1631. [PMID: 6337142]
7.  Lenz, R. and Giese, B. Studies on the Mechanism of Ribonucleotide Reductases. J. Am. Chem. Soc. 119 (1997) 2784–2794.
8.  Lawrence, C.C., Bennati, M., Obias, H.V., Bar, G., Griffin, R.G. and Stubbe, J. High-field EPR detection of a disulfide radical anion in the reduction of cytidine 5′-diphosphate by the E441Q R1 mutant of Escherichia coli ribonucleotide reductase. Proc. Natl. Acad. Sci. USA 96 (1999) 8979–8984. [DOI] [PMID: 10430881]
9.  Qiu, W., Zhou, B., Darwish, D., Shao, J. and Yen, Y. Characterization of enzymatic properties of human ribonucleotide reductase holoenzyme reconstituted in vitro from hRRM1, hRRM2, and p53R2 subunits. Biochem. Biophys. Res. Commun. 340 (2006) 428–434. [DOI] [PMID: 16376858]
[EC 1.17.4.1 created 1972, modified 2017]
 
 
EC 1.17.4.2     
Accepted name: ribonucleoside-triphosphate reductase (thioredoxin)
Reaction: 2′-deoxyribonucleoside 5′-triphosphate + thioredoxin disulfide + H2O = ribonucleoside 5′-triphosphate + thioredoxin
Other name(s): ribonucleotide reductase (ambiguous); 2′-deoxyribonucleoside-triphosphate:oxidized-thioredoxin 2′-oxidoreductase
Systematic name: 2′-deoxyribonucleoside-5′-triphosphate:thioredoxin-disulfide 2′-oxidoreductase
Comments: The enzyme, characterized from the bacterium Lactobacillus leichmannii, is similar to class II ribonucleoside-diphosphate reductase (cf. EC 1.17.4.1). However, it is specific for the triphosphate versions of its substrates. The enzyme contains an adenosylcobalamin cofactor that is involved in generation of a transient thiyl (sulfanyl) radical on a cysteine residue. This radical attacks the substrate, forming a ribonucleotide 3′-radical, followed by water loss to form a ketyl (α-oxoalkyl) radical. The ketyl radical is reduced to 3′-keto-deoxynucleotide concomitant with formation of a disulfide anion radical between two cysteine residues. A proton-coupled electron-transfer from the disulfide radical to the substrate generates a 3′-deoxynucleotide radical, and the final product is formed when the hydrogen atom that was initially removed from the 3′-position of the nucleotide by the thiyl radical is returned to the same position. The disulfide bridge is reduced by the action of thioredoxin. cf. EC 1.1.98.6, ribonucleoside-triphosphate reductase (formate).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9068-66-0
References:
1.  Blakley, R.L. Cobamides and ribonucleotide reduction. I. Cobamide stimulation of ribonucleotide reduction in extracts of Lactobacillus leichmannii. J. Biol. Chem. 240 (1965) 2173–2180. [PMID: 14299643]
2.  Goulian, M. and Beck, W.S. Purification and properties of cobamide-dependent ribonucleotide reductase from Lactobacillus leichmannii. J. Biol. Chem. 241 (1966) 4233–4242. [PMID: 5924645]
3.  Stubbe, J., Ackles, D., Segal, R. and Blakley, R.L. On the mechanism of ribonucleoside triphosphate reductase from Lactobacillus leichmannii. Evidence for 3′ C--H bond cleavage. J. Biol. Chem. 256 (1981) 4843–4846. [PMID: 7014560]
4.  Ashley, G.W., Harris, G. and Stubbe, J. The mechanism of Lactobacillus leichmannii ribonucleotide reductase. Evidence for 3′ carbon-hydrogen bond cleavage and a unique role for coenzyme B12. J. Biol. Chem. 261 (1986) 3958–3964. [PMID: 3512563]
5.  Lawrence, C.C. and Stubbe, J. The function of adenosylcobalamin in the mechanism of ribonucleoside triphosphate reductase from Lactobacillus leichmannii. Curr. Opin. Chem. Biol. 2 (1998) 650–655. [DOI] [PMID: 9818192]
6.  Licht, S.S., Booker, S. and Stubbe, J. Studies on the catalysis of carbon-cobalt bond homolysis by ribonucleoside triphosphate reductase: evidence for concerted carbon-cobalt bond homolysis and thiyl radical formation. Biochemistry 38 (1999) 1221–1233. [DOI] [PMID: 9930982]
[EC 1.17.4.2 created 1972, modified 2017]
 
 
EC 1.17.99.6     
Accepted name: epoxyqueuosine reductase
Reaction: queuosine34 in tRNA + acceptor + H2O = epoxyqueuosine34 in tRNA + reduced acceptor
For diagram of queuine biosynthesis, click here
Glossary: queuine = base Q = 2-amino-5-({[(1S,4S,5R)-4,5-dihydroxycyclopent-2-en-1-yl]amino}methyl)-1,7-dihydropyrrolo[3,2-e]pyrimidin-4-one
epoxyqueine = base oQ
Other name(s): oQ reductase; queG (gene name); queH (gene name)
Systematic name: queuosine34 in tRNA:acceptor oxidoreductase
Comments: This enzyme catalyses the last step in the bacterial biosynthetic pathway to queuosine, the modified guanosine base in the wobble position in tRNAs specific for Tyr, His, Asp or Asn. Two types of enzymes are known to catalyse this activity. QueG enzymes are cobalamin-dependent, while QueH enzymes contain a [4Fe-4S] metallocluster along with an adjacent coordinated iron metal.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB
References:
1.  Miles, Z.D., McCarty, R.M., Molnar, G. and Bandarian, V. Discovery of epoxyqueuosine (oQ) reductase reveals parallels between halorespiration and tRNA modification. Proc. Natl. Acad. Sci. USA 108 (2011) 7368–7372. [DOI] [PMID: 21502530]
2.  Zallot, R., Ross, R., Chen, W.H., Bruner, S.D., Limbach, P.A. and De Crecy-Lagard, V. Identification of a novel epoxyqueuosine reductase family by comparative genomics. ACS Chem. Biol. 12 (2017) 844–851. [DOI] [PMID: 28128549]
3.  Li, Q., Zallot, R., MacTavish, B.S., Montoya, A., Payan, D.J., Hu, Y., Gerlt, J.A., Angerhofer, A., de Crecy-Lagard, V. and Bruner, S.D. Epoxyqueuosine reductase QueH in the biosynthetic pathway to tRNA queuosine is a unique metalloenzyme. Biochemistry 60 (2021) 3152–3161. [DOI] [PMID: 34652139]
[EC 1.17.99.6 created 2014]
 
 
EC 1.17.99.10     
Accepted name: steroid C-25 hydroxylase
Reaction: cholest-4-en-3-one + acceptor + H2O = 25-hydroxycholest-4-en-3-one + reduced acceptor
Other name(s): s25dA1 (gene name); s25dA1B3 (gene name); s25dA1C3 (gene name); cholesterol C-25 dehydrogenase; steroid C-25 dehydrogenase
Systematic name: cholest-4-en-3-one:acceptor oxidoreductase (25-hydroxylating)
Comments: The enzyme, characterized from the bacterium Sterolibacterium denitrificans, participates in the anaerobic degradation of cholesterol. The enzyme can accept several substrates including vitamin D3. The enzyme contains a bis(guanylyl molybdopterin) cofactor, five [Fe-S] clusters, and one heme b. cf. EC 1.14.99.38, cholesterol 25-monooxygenase, an oxygen-requiring eukaryotic enzyme that catalyses a similar transformation.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Dermer, J. and Fuchs, G. Molybdoenzyme that catalyzes the anaerobic hydroxylation of a tertiary carbon atom in the side chain of cholesterol. J. Biol. Chem. 287 (2012) 36905–36916. [DOI] [PMID: 22942275]
2.  Rugor, A., Tataruch, M., Staron, J., Dudzik, A., Niedzialkowska, E., Nowak, P., Hogendorf, A., Michalik-Zym, A., Napruszewska, D.B., Jarzebski, A., Szymanska, K., Bialas, W. and Szaleniec, M. Regioselective hydroxylation of cholecalciferol, cholesterol and other sterol derivatives by steroid C25 dehydrogenase. Appl. Microbiol. Biotechnol. 101 (2017) 1163–1174. [DOI] [PMID: 27726023]
3.  Rugor, A., Wojcik-Augustyn, A., Niedzialkowska, E., Mordalski, S., Staron, J., Bojarski, A. and Szaleniec, M. Reaction mechanism of sterol hydroxylation by steroid C25 dehydrogenase - Homology model, reactivity and isoenzymatic diversity. J. Inorg. Biochem. 173 (2017) 28–43. [DOI] [PMID: 28482186]
4.  Jacoby, C., Eipper, J., Warnke, M., Tiedt, O., Mergelsberg, M., Stark, H.J., Daus, B., Martin-Moldes, Z., Zamarro, M.T., Diaz, E. and Boll, M. Four molybdenum-dependent steroid C-25 hydroxylases: heterologous overproduction, role in steroid degradation, and application for 25-hydroxyvitamin D3 synthesis. mBio 9:e00694-18 (2018). [DOI] [PMID: 29921665]
[EC 1.17.99.10 created 2020]
 
 
EC 1.21.98.3     
Accepted name: anaerobic magnesium-protoporphyrin IX monomethyl ester cyclase
Reaction: magnesium-protoporphyrin IX 13-monomethyl ester + 3 S-adenosyl-L-methionine + H2O = 3,8-divinyl protochlorophyllide a + 3 5′-deoxyadenosine + 3 L-methionine (overall reaction)
(1a) magnesium-protoporphyrin IX 13-monomethyl ester + S-adenosyl-L-methionine + H2O = 131-hydroxy-magnesium-protoporphyrin IX 13-monomethyl ester + 5′-deoxyadenosine + L-methionine
(1b) 131-hydroxy-magnesium-protoporphyrin IX 13-monomethyl ester + S-adenosyl-L-methionine = 131-oxo-magnesium-protoporphyrin IX 13-monomethyl ester + 5′-deoxyadenosine + L-methionine
(1c) 131-oxo-magnesium-protoporphyrin IX 13-monomethyl ester + S-adenosyl-L-methionine = 3,8-divinyl protochlorophyllide a + 5′-deoxyadenosine + L-methionine
For diagram of chlorophyll biosynthesis (earlier stages), click here
Other name(s): bchE (gene name); MPE cyclase (ambiguous)
Systematic name: magnesium-protoporphyrin-IX 13-monomethyl ester,S-adenosyl-L-methionine:H2O oxidoreductase (hydroxylating)
Comments: This radical AdoMet enzyme participates in the biosynthesis of chlorophyllide a in anaerobic bacteria, catalysing the formation of an isocyclic ring. Contains a [4Fe-4S] cluster and a cobalamin cofactor. The same transformation is achieved in aerobic organisms by the oxygen-dependent EC 1.14.13.81, magnesium-protoporphyrin IX monomethyl ester (oxidative) cyclase. Some facultative phototrophic bacteria, such as Rubrivivax gelatinosus, possess both enzymes.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Yang, Z.M. and Bauer, C.E. Rhodobacter capsulatus genes involved in early steps of the bacteriochlorophyll biosynthetic pathway. J. Bacteriol. 172 (1990) 5001–5010. [DOI] [PMID: 2203738]
2.  Gough, S.P., Petersen, B.O. and Duus, J.O. Anaerobic chlorophyll isocyclic ring formation in Rhodobacter capsulatus requires a cobalamin cofactor. Proc. Natl. Acad. Sci. USA 97 (2000) 6908–6913. [DOI] [PMID: 10841582]
3.  Ouchane, S., Steunou, A.S., Picaud, M. and Astier, C. Aerobic and anaerobic Mg-protoporphyrin monomethyl ester cyclases in purple bacteria: a strategy adopted to bypass the repressive oxygen control system. J. Biol. Chem. 279 (2004) 6385–6394. [DOI] [PMID: 14617630]
4.  Booker, S.J. Anaerobic functionalization of unactivated C-H bonds. Curr. Opin. Chem. Biol. 13 (2009) 58–73. [DOI] [PMID: 19297239]
[EC 1.21.98.3 created 2016]
 
 
EC 1.21.99.5     
Accepted name: tetrachloroethene reductive dehalogenase
Reaction: trichloroethene + chloride + acceptor = tetrachloroethene + reduced acceptor
Glossary: methyl viologen = 1,1′-dimethyl-4,4′-bipyridine-1,1′-diium
Other name(s): tetrachloroethene reductase
Systematic name: acceptor:trichloroethene oxidoreductase (chlorinating)
Comments: This enzyme allows the common pollutant tetrachloroethene to support bacterial growth and is responsible for disposal of a number of chlorinated hydrocarbons. The reaction occurs in the reverse direction. The enzyme also reduces trichloroethene to dichloroethene. Although the physiological reductant is unknown, the supply of reductant in some organisms involves menaquinol, which is reduced by molecular hydrogen via the action of EC 1.12.5.1, hydrogen:quinone oxidoreductase. The enzyme contains a corrinoid and two iron-sulfur clusters. Methyl viologen can act as electron donor in vitro.
Links to other databases: BRENDA, EAWAG-BBD, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 163913-51-7
References:
1.  Holliger, C, Wohlfarth, G. and Diekert, G. Reductive dechlorination in the energy metabolism of anaerobic bacteria. FEMS Microbiol. Rev. 22 (1998) 383–398.
2.  Glod, G., Angst, W., Holliger, C. and Schwarzenbach, R.P. Corrinoid-mediated reduction of tetrachloroethene, trichloroethene, and trichlorofluoroethene in homogeneous aqueous solution: Reaction kinetics and reaction mechanisms. Environ. Sci. Technol. 31 (1997) 253–260.
3.  Neumann, A., Wohlfarth, G. and Diekert, G. Purification and characterization of tetrachloroethene reductive dehalogenase from Dehalospirillum multivorans. J. Biol. Chem. 271 (1996) 16515–16519. [DOI] [PMID: 8663199]
4.  Schumacher, W., Holliger, C., Zehnder, A.J.B. and Hagen, W.R. Redox chemistry of cobalamin and iron-sulfur cofactors in the tetrachloroethene reductase of Dehalobacter restrictus. FEBS Lett. 409 (1997) 421–425. [DOI] [PMID: 9224702]
5.  Schumacher, W. and Holliger, C. The proton/electron ratio of the menaquinone-dependent electron transport from dihydrogen to tetrachloroethene in "Dehalobacter restrictus". J. Bacteriol. 178 (1996) 2328–2333. [DOI] [PMID: 8636034]
[EC 1.21.99.5 created 2001 as EC 1.97.1.8, transferred 2017 to EC 1.21.99.5]
 
 
EC 1.97.1.8      
Transferred entry: tetrachloroethene reductive dehalogenase. Now EC 1.21.99.5, tetrachloroethene reductive dehalogenase
[EC 1.97.1.8 created 2001, deleted 2017]
 
 
EC 2.1.1.13     
Accepted name: methionine synthase
Reaction: 5-methyltetrahydrofolate + L-homocysteine = tetrahydrofolate + L-methionine
For diagram of reaction, click here
Other name(s): 5-methyltetrahydrofolate—homocysteine S-methyltransferase; 5-methyltetrahydrofolate—homocysteine transmethylase; N-methyltetrahydrofolate:L-homocysteine methyltransferase; N5-methyltetrahydrofolate methyltransferase; N5-methyltetrahydrofolate-homocysteine cobalamin methyltransferase; N5-methyltetrahydrofolic—homocysteine vitamin B12 transmethylase; B12 N5-methyltetrahydrofolate homocysteine methyltransferase; methyltetrahydrofolate—homocysteine vitamin B12 methyltransferase; tetrahydrofolate methyltransferase; tetrahydropteroylglutamate methyltransferase; tetrahydropteroylglutamic methyltransferase; vitamin B12 methyltransferase; cobalamin-dependent methionine synthase; methionine synthase (cobalamin-dependent); MetH
Systematic name: 5-methyltetrahydrofolate:L-homocysteine S-methyltransferase
Comments: Contains zinc and cobamide. The enzyme becomes inactivated occasionally during its cycle by oxidation of Co(I) to Co(II). Reactivation by reductive methylation is catalysed by the enzyme itself, with S-adenosyl-L-methionine as the methyl donor and a reducing system. For the mammalian enzyme, the reducing system involves NADPH and EC 1.16.1.8, [methionine synthase] reductase. In bacteria, the reducing agent is flavodoxin, and no further catalyst is needed (the flavodoxin is kept in the reduced state by NADPH and EC 1.18.1.2, ferredoxin—NADP+ reductase). Acts on the monoglutamate as well as the triglutamate folate, in contrast with EC 2.1.1.14, 5-methyltetrahydropteroyltriglutamate—homocysteine S-methyltransferase, which acts only on the triglutamate.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9033-23-2
References:
1.  Burton, E.G. and Sakami, W. The formation of methionine from the monoglutamate form of methyltetrahydrofolate by higher plants. Biochem. Biophys. Res. Commun. 36 (1969) 228–234. [DOI] [PMID: 5799642]
2.  Foster, M.A., Dilworth, M.J. and Woods, D.D. Cobalamin and the synthesis of methionine by Escherichia coli. Nature 201 (1964) 39–42. [PMID: 14085561]
3.  Guest, J.R., Friedman, S., Foster, M.A., Tejerina, G. and Woods, D.D. Transfer of the methyl group from N5-methyltetrahydrofolates to homocysteine in Escherichia coli. Biochem. J. 92 (1964) 497–504. [PMID: 5319972]
4.  Loughlin, R.E., Elford, H.L. and Buchanan, J.M. Enzymatic synthesis of the methyl group of methionine. VII. Isolation of a cobalamin-containing transmethylase (5-methyltetrahydro-folate-homocysteine) from mammalian liver. J. Biol. Chem. 239 (1964) 2888–2895. [PMID: 14216440]
5.  Taylor, R.T. Escherichia coli B N 5 -methyltetrahydrofolate-homocysteine cobalamin methyltransferase: gel-filtration behavior of apoenzyme and holoenzymes. Biochim. Biophys. Acta 242 (1971) 355–364. [DOI] [PMID: 4946148]
6.  Jarrett, J.T., Huang, S. and Matthews, R.G. Methionine synthase exists in two distinct conformations that differ in reactivity toward methyltetrahydrofolate, adenosylmethionine, and flavodoxin. Biochemistry 37 (1998) 5372–5382. [DOI] [PMID: 9548919]
7.  Peariso, K., Goulding, C.W., Huang, S., Matthews, R.G. and Penner-Hahn, J.E. Characterization of the zinc binding site in methionine synthase enzymes of Escherichia coli: The role of zinc in the methylation of homocysteine. J. Am. Chem. Soc. 120 (1998) 8410–8416.
8.  Hall, D.A., Jordan-Starck, T.C., Loo, R.O., Ludwig, M.L. and Matthews, R.G. Interaction of flavodoxin with cobalamin-dependent methionine synthase. Biochemistry 39 (2000) 10711–10719. [DOI] [PMID: 10978155]
9.  Bandarian, V., Pattridge, K.A., Lennon, B.W., Huddler, D.P., Matthews, R.G. and Ludwig, M.L. Domain alternation switches B12-dependent methionine synthase to the activation conformation. Nat. Struct. Biol. 9 (2002) 53–56. [DOI] [PMID: 11731805]
[EC 2.1.1.13 created 1972, modified 2003]
 
 
EC 2.1.1.14     
Accepted name: 5-methyltetrahydropteroyltriglutamate—homocysteine S-methyltransferase
Reaction: 5-methyltetrahydropteroyltri-L-glutamate + L-homocysteine = tetrahydropteroyltri-L-glutamate + L-methionine
For diagram of L-Methionine biosynthesis, click here
Other name(s): tetrahydropteroyltriglutamate methyltransferase; homocysteine methylase; methyltransferase, tetrahydropteroylglutamate-homocysteine transmethylase; methyltetrahydropteroylpolyglutamate:homocysteine methyltransferase; cobalamin-independent methionine synthase; methionine synthase (cobalamin-independent); MetE
Systematic name: 5-methyltetrahydropteroyltri-L-glutamate:L-homocysteine S-methyltransferase
Comments: Requires phosphate and contains zinc. The enzyme from Escherichia coli also requires a reducing system. Unlike EC 2.1.1.13, methionine synthase, this enzyme does not contain cobalamin.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9068-29-5
References:
1.  Guest, J.R., Friedman, S., Foster, M.A., Tejerina, G. and Woods, D.D. Transfer of the methyl group from N5-methyltetrahydrofolates to homocysteine in Escherichia coli. Biochem. J. 92 (1964) 497–504. [PMID: 5319972]
2.  Whitfield, C.D., Steers, E.J., Jr. and Weissbach, H. Purification and properties of 5-methyltetrahydropteroyltriglutamate-homocysteine transmethylase. J. Biol. Chem. 245 (1970) 390–401. [PMID: 4904482]
3.  Eichel, J., Gonzalez, J.C., Hotze, M., Matthews, R.G. and Schroder, J. Vitamin B12-independent methionine synthase from a higher-plant (Catharanthus roseus) - molecular characterization, regulation, heterologous expression, and enzyme properties. Eur. J. Biochem. 230 (1995) 1053–1058. [DOI] [PMID: 7601135]
4.  Gonzalez, J.C., Peariso, K., PennerHahn, J.E. and Matthews, R.G. Cobalamin-independent methionine synthase from Escherichia coli: A zinc metalloenzyme. Biochemistry 35 (1996) 12228–12234. [DOI] [PMID: 8823155]
5.  Peariso, K., Goulding, C.W., Huang, S., Matthews, R.G. and Penner-Hahn, J.E. Characterization of the zinc binding site in methionine synthase enzymes of Escherichia coli: The role of zinc in the methylation of homocysteine. J. Am. Chem. Soc. 120 (1998) 8410–8416.
[EC 2.1.1.14 created 1972, modified 2003]
 
 
EC 2.1.1.16     
Accepted name: methylene-fatty-acyl-phospholipid synthase
Reaction: S-adenosyl-L-methionine + phospholipid olefinic fatty acid = S-adenosyl-L-homocysteine + phospholipid methylene fatty acid
Other name(s): unsaturated-phospholipid methyltransferase
Systematic name: S-adenosyl-L-methionine:unsaturated-phospholipid methyltransferase (methenylating)
Comments: The enzyme transfers a methyl group to the 10-position of a Δ-olefinic acyl chain in phosphatidylglycerol or phosphatidylinositol or, more slowly, phosphatidylethanolamine; subsequent proton transfer produces a 10-methylene group (cf. EC 2.1.1.79 cyclopropane-fatty-acyl-phospholipid synthase).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 37256-90-9
References:
1.  Akamatsu, Y. and Law, J.H. Enzymatic alkylenation of phospholipid fatty acid chains by extracts of Mycobacterium phlei. J. Biol. Chem. 245 (1970) 701–708. [PMID: 4313604]
[EC 2.1.1.16 created 1972, modified 1986]
 
 
EC 2.1.1.18     
Accepted name: polysaccharide O-methyltransferase
Reaction: S-adenosyl-L-methionine + a (1→4)-α-D-glucooligosaccharide = S-adenosyl-L-homocysteine + an oligosaccharide containing 6-methyl-D-glucose units
Other name(s): polysaccharide methyltransferase; acylpolysacharide 6-methyltransferase; S-adenosyl-L-methionine:1,4-α-D-glucan 6-O-methyltransferase
Systematic name: S-adenosyl-L-methionine:(1→4)-α-D-glucan 6-O-methyltransferase
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 37205-56-4
References:
1.  Ferguson, J.A. and Ballou, C.E. Biosynthesis of a mycobacterial lipopolysaccharide. Properties of the polysaccharide methyltransferase. J. Biol. Chem. 245 (1970) 4213–4223. [PMID: 5503262]
[EC 2.1.1.18 created 1972]
 
 
EC 2.1.1.44     
Accepted name: L-histidine Nα-methyltransferase
Reaction: 3 S-adenosyl-L-methionine + L-histidine = 3 S-adenosyl-L-homocysteine + hercynine (overall reaction)
(1a) S-adenosyl-L-methionine + L-histidine = S-adenosyl-L-homocysteine + Nα-methyl-L-histidine
(1b) S-adenosyl-L-methionine + Nα-methyl-L-histidine = S-adenosyl-L-homocysteine + Nα,Nα-dimethyl-L-histidine
(1c) S-adenosyl-L-methionine + Nα,Nα-dimethyl-L-histidine = S-adenosyl-L-homocysteine + hercynine
For diagram of ergothioneine and ovothiol biosynthesis, click here
Glossary: hercynine = Nα,Nα,Nα-trimethyl-L-histidine
Other name(s): dimethylhistidine N-methyltransferase; dimethylhistidine methyltransferase; histidine-α-N-methyltransferase; S-adenosyl-L-methionine:α-N,α-N-dimethyl-L-histidine α-N-methyltransferase; S-adenosyl-L-methionine:Nα,Nα-dimethyl-L-histidine Nα-methyltransferase
Systematic name: S-adenosyl-L-methionine:L-histidine Nα-methyltransferase (hercynine-forming)
Comments: Part of the biosynthetic pathway of ergothioneine.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 62213-53-0
References:
1.  Ishikawa, Y. and Melville, D.B. The enzymatic α-N-methylation of histidine. J. Biol. Chem. 245 (1970) 5967–5973. [PMID: 5484456]
2.  Seebeck, F.P. In vitro reconstitution of mycobacterial ergothioneine biosynthesis. J. Am. Chem. Soc. 132 (2010) 6632–6633. [DOI] [PMID: 20420449]
[EC 2.1.1.44 created 1976, modified 2013]
 
 


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