The Enzyme Database

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EC 1.1.3.17     
Accepted name: choline oxidase
Reaction: choline + 2 O2 + H2O = betaine + 2 H2O2 (overall reaction)
(1a) choline + O2 = betaine aldehyde + H2O2
(1b) betaine aldehyde + O2 + H2O = betaine + H2O2
Glossary: choline = (2-hydroxyethyl)trimethylammonium
betaine aldehyde = N,N,N-trimethyl-2-oxoethylammonium
betaine = glycine betaine = N,N,N-trimethylglycine = N,N,N-trimethylammonioacetate
Systematic name: choline:oxygen 1-oxidoreductase
Comments: A flavoprotein (FAD). In many bacteria, plants and animals, the osmoprotectant betaine is synthesized using different enzymes to catalyse the conversion of (1) choline into betaine aldehyde and (2) betaine aldehyde into betaine. In plants, the first reaction is catalysed by EC 1.14.15.7, choline monooxygenase, whereas in animals and many bacteria, it is catalysed by either membrane-bound choline dehydrogenase (EC 1.1.99.1) or soluble choline oxidase (EC 1.1.3.17) [6]. The enzyme involved in the second step, EC 1.2.1.8, betaine-aldehyde dehydrogenase, appears to be the same in those plants, animals and bacteria that use two separate enzymes.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 9028-67-5
References:
1.  Ikuta, S., Imamura, S., Misaki, H. and Horiuti, Y. Purification and characterization of choline oxidase from Arthrobacter globiformis. J. Biochem. (Tokyo) 82 (1977) 1741–1749. [PMID: 599154]
2.  Rozwadowski, K.L., Khachatourians, G.G. and Selvaraj, G. Choline oxidase, a catabolic enzyme in Arthrobacter pascens, facilitates adaptation to osmotic stress in Escherichia coli. J. Bacteriol. 173 (1991) 472–478. [DOI] [PMID: 1987142]
3.  Rand, T., Halkier, T. and Hansen, O.C. Structural characterization and mapping of the covalently linked FAD cofactor in choline oxidase from Arthrobacter globiformis. Biochemistry 42 (2003) 7188–7194. [DOI] [PMID: 12795615]
4.  Gadda, G., Powell, N.L. and Menon, P. The trimethylammonium headgroup of choline is a major determinant for substrate binding and specificity in choline oxidase. Arch. Biochem. Biophys. 430 (2004) 264–273. [DOI] [PMID: 15369826]
5.  Fan, F. and Gadda, G. On the catalytic mechanism of choline oxidase. J. Am. Chem. Soc. 127 (2005) 2067–2074. [DOI] [PMID: 15713082]
6.  Waditee, R., Tanaka, Y., Aoki, K., Hibino, T., Jikuya, H., Takano, J., Takabe, T. and Takabe, T. Isolation and functional characterization of N-methyltransferases that catalyze betaine synthesis from glycine in a halotolerant photosynthetic organism Aphanothece halophytica. J. Biol. Chem. 278 (2003) 4932–4942. [DOI] [PMID: 12466265]
7.  Fan, F., Ghanem, M. and Gadda, G. Cloning, sequence analysis, and purification of choline oxidase from Arthrobacter globiformis: a bacterial enzyme involved in osmotic stress tolerance. Arch. Biochem. Biophys. 421 (2004) 149–158. [DOI] [PMID: 14678796]
8.  Gadda, G. Kinetic mechanism of choline oxidase from Arthrobacter globiformis. Biochim. Biophys. Acta 1646 (2003) 112–118. [DOI] [PMID: 12637017]
[EC 1.1.3.17 created 1978, modified 2005, modified 2007]
 
 
EC 1.1.99.1     
Accepted name: choline dehydrogenase
Reaction: choline + acceptor = betaine aldehyde + reduced acceptor
Glossary: betaine aldehyde = N,N,N-trimethyl-2-oxoethylammonium
choline = (2-hydroxyethyl)trimethylammonium
Other name(s): choline oxidase; choline-cytochrome c reductase; choline:(acceptor) oxidoreductase; choline:(acceptor) 1-oxidoreductase
Systematic name: choline:acceptor 1-oxidoreductase
Comments: A quinoprotein. In many bacteria, plants and animals, the osmoprotectant betaine is synthesized using different enzymes to catalyse the conversion of (1) choline into betaine aldehyde and (2) betaine aldehyde into betaine. In plants, the first reaction is catalysed by EC 1.14.15.7, choline monooxygenase, whereas in animals and many bacteria, it is catalysed by either membrane-bound choline dehydrogenase (EC 1.1.99.1) or soluble choline oxidase (EC 1.1.3.17) [4]. The enzyme involved in the second step, EC 1.2.1.8, betaine-aldehyde dehydrogenase, appears to be the same in plants, animals and bacteria.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 9028-67-5
References:
1.  Ameyama, M., Shinagawa, E., Matsuchita, K., Takimoto, K., Nakashima, K. and Adachi, O. Mammalian choline dehydrogenase is a quinoprotein. Agric. Biol. Chem. 49 (1985) 3623–3626.
2.  Ebisuzaki, K. and Williams, J.N. Preparation and partial purification of soluble choline dehydrogenase from liver mitochondria. Biochem. J. 60 (1955) 644–646. [PMID: 13249959]
3.  Gadda, G. and McAllister-Wilkins, E.E. Cloning, expression, and purification of choline dehydrogenase from the moderate halophile Halomonas elongata. Appl. Environ. Microbiol. 69 (2003) 2126–2132. [DOI] [PMID: 12676692]
4.  Waditee, R., Tanaka, Y., Aoki, K., Hibino, T., Jikuya, H., Takano, J., Takabe, T. and Takabe, T. Isolation and functional characterization of N-methyltransferases that catalyze betaine synthesis from glycine in a halotolerant photosynthetic organism Aphanothece halophytica. J. Biol. Chem. 278 (2003) 4932–4942. [DOI] [PMID: 12466265]
[EC 1.1.99.1 created 1961, modified 1989, modified 2005]
 
 
EC 1.2.1.8     
Accepted name: betaine-aldehyde dehydrogenase
Reaction: betaine aldehyde + NAD+ + H2O = betaine + NADH + 2 H+
Glossary: betaine = glycine betaine = N,N,N-trimethylglycine = N,N,N-trimethylammonioacetate
betaine aldehyde = N,N,N-trimethyl-2-oxoethylammonium
Other name(s): betaine aldehyde oxidase; BADH; betaine aldehyde dehydrogenase; BetB
Systematic name: betaine-aldehyde:NAD+ oxidoreductase
Comments: In many bacteria, plants and animals, the osmoprotectant betaine is synthesized in two steps: (1) choline to betaine aldehyde and (2) betaine aldehyde to betaine. This enzyme is involved in the second step and appears to be the same in plants, animals and bacteria. In contrast, different enzymes are involved in the first reaction. In plants, this reaction is catalysed by EC 1.14.15.7 (choline monooxygenase), whereas in animals and many bacteria it is catalysed by either membrane-bound EC 1.1.99.1 (choline dehydrogenase) or soluble EC 1.1.3.17 (choline oxidase) [5]. In some bacteria, betaine is synthesized from glycine through the actions of EC 2.1.1.156 (glycine/sarcosine N-methyltransferase) and EC 2.1.1.157 (sarcosine/dimethylglycine N-methyltransferase).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9028-90-4
References:
1.  Rothschild, H.A. and Barron, E.S.G. The oxidation of betaine aldehyde by betaine aldehyde dehydrogenase. J. Biol. Chem. 209 (1954) 511–523. [PMID: 13192104]
2.  Livingstone, J.R., Maruo, T., Yoshida, I., Tarui, Y., Hirooka, K., Yamamoto, Y., Tsutui, N. and Hirasawa, E. Purification and properties of betaine aldehyde dehydrogenase from Avena sativa. J. Plant Res. 116 (2003) 133–140. [DOI] [PMID: 12736784]
3.  Muñoz-Clares, R.A., González-Segura, L., Mújica-Jiménez, C. and Contreras-Diaz, L. Ligand-induced conformational changes of betaine aldehyde dehydrogenase from Pseudomonas aeruginosa and Amaranthus hypochondriacus L. leaves affecting the reactivity of the catalytic thiol. Chem. Biol. Interact. (2003) 129–137. [DOI] [PMID: 12604197]
4.  Johansson, K., El-Ahmad, M., Ramaswamy, S., Hjelmqvist, L., Jornvall, H. and Eklund, H. Structure of betaine aldehyde dehydrogenase at 2.1 Å resolution. Protein Sci. 7 (1998) 2106–2117. [DOI] [PMID: 9792097]
5.  Waditee, R., Tanaka, Y., Aoki, K., Hibino, T., Jikuya, H., Takano, J., Takabe, T. and Takabe, T. Isolation and functional characterization of N-methyltransferases that catalyze betaine synthesis from glycine in a halotolerant photosynthetic organism Aphanothece halophytica. J. Biol. Chem. 278 (2003) 4932–4942. [DOI] [PMID: 12466265]
[EC 1.2.1.8 created 1961, modified 2005, modified 2011]
 
 
EC 1.2.1.73     
Accepted name: sulfoacetaldehyde dehydrogenase
Reaction: 2-sulfoacetaldehyde + H2O + NAD+ = sulfoacetate + NADH + 2 H+
Glossary: 2-sulfoacetaldehyde = 2-oxoethanesulfonate
taurine = 2-aminoethanesulfonate
Other name(s): SafD
Systematic name: 2-sulfoacetaldehyde:NAD+ oxidoreductase
Comments: This reaction is part of a bacterial pathway that can utilize the amino group of taurine as a sole source of nitrogen for growth. At physiological concentrations, NAD+ cannot be replaced by NADP+. The enzyme is specific for sulfoacetaldehyde, as formaldehyde, acetaldehyde, betaine aldehyde, propanal, glyceraldehyde, phosphonoacetaldehyde, glyoxylate, glycolaldehyde and 2-oxobutyrate are not substrates.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Krejčík, Z., Denger, K., Weinitschke, S., Hollemeyer, K., Pačes, V., Cook, A.M. and Smits, T.H.M. Sulfoacetate released during the assimilation of taurine-nitrogen by Neptuniibacter caesariensis: purification of sulfoacetaldehyde dehydrogenase. Arch. Microbiol. 190 (2008) 159–168. [DOI] [PMID: 18506422]
[EC 1.2.1.73 created 2008]
 
 
EC 1.3.8.13     
Accepted name: crotonobetainyl-CoA reductase
Reaction: γ-butyrobetainyl-CoA + electron-transfer flavoprotein = crotonobetainyl-CoA + reduced electron-transfer flavoprotein
Glossary: γ-butyrobetainyl-CoA = 4-(trimethylammonio)butanoyl-CoA
crotonobetainyl-CoA = (E)-4-(trimethylammonio)but-2-enoyl-CoA
Other name(s): caiA (gene name)
Systematic name: γ-butyrobetainyl-CoA:electron-transfer flavoprotein 2,3-oxidoreductase
Comments: The enzyme has been purified from the bacterium Escherichia coli O44 K74, in which it forms a complex with EC 2.8.3.21, L-carnitine CoA-transferase. The electron donor is believed to be an electron-transfer flavoprotein (ETF) encoded by the fixA and fixB genes.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Roth, S., Jung, K., Jung, H., Hommel, R.K. and Kleber, H.P. Crotonobetaine reductase from Escherichia coli - a new inducible enzyme of anaerobic metabolization of L(–)-carnitine. Antonie Van Leeuwenhoek 65 (1994) 63–69. [PMID: 8060125]
2.  Preusser, A., Wagner, U., Elssner, T. and Kleber, H.P. Crotonobetaine reductase from Escherichia coli consists of two proteins. Biochim. Biophys. Acta 1431 (1999) 166–178. [DOI] [PMID: 10209289]
3.  Elssner, T., Hennig, L., Frauendorf, H., Haferburg, D. and Kleber, H.P. Isolation, identification, and synthesis of γ-butyrobetainyl-CoA and crotonobetainyl-CoA, compounds involved in carnitine metabolism of E. coli. Biochemistry 39 (2000) 10761–10769. [DOI] [PMID: 10978161]
4.  Walt, A. and Kahn, M.L. The fixA and fixB genes are necessary for anaerobic carnitine reduction in Escherichia coli. J. Bacteriol. 184 (2002) 4044–4047. [DOI] [PMID: 12081978]
[EC 1.3.8.13 created 2017]
 
 
EC 1.13.11.90     
Accepted name: [1-hydroxy-2-(trimethylamino)ethyl]phosphonate dioxygenase (glycine-betaine-forming)
Reaction: [(1R)-1-hydroxy-2-(trimethylamino)ethyl]phosphonate + O2 = glycine betaine + phosphate
Other name(s): tmpB (gene name)
Systematic name: [(1R)-1-hydroxy-2-(trimethylamino)ethyl]phosphonate:oxygen 1R-oxidoreductase (glycine-betaine-forming)
Comments: Requires Fe2+. This bacterial enzyme is involved in a degradation pathway for [2-(trimethylamino)ethyl]phosphonate.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Rajakovich, L.J., Pandelia, M.E., Mitchell, A.J., Chang, W.C., Zhang, B., Boal, A.K., Krebs, C. and Bollinger, J.M., Jr. A new microbial pathway for organophosphonate degradation catalyzed by two previously misannotated non-heme-iron oxygenases. Biochemistry 58 (2019) 1627–1647. [PMID: 30789718]
[EC 1.13.11.90 created 2020]
 
 
EC 1.14.11.1     
Accepted name: γ-butyrobetaine dioxygenase
Reaction: 4-trimethylammoniobutanoate + 2-oxoglutarate + O2 = 3-hydroxy-4-trimethylammoniobutanoate + succinate + CO2
Other name(s): α-butyrobetaine hydroxylase; γ-butyrobetaine hydroxylase; butyrobetaine hydroxylase
Systematic name: 4-trimethylammoniobutanoate,2-oxoglutarate:oxygen oxidoreductase (3-hydroxylating)
Comments: Requires Fe2+ and ascorbate.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 9045-31-2
References:
1.  Lindstedt, G. and Lindstedt, S. Cofactor requirements of γ-butyrobetaine hydroxylase from rat liver. J. Biol. Chem. 245 (1970) 4178–4186. [PMID: 4396068]
[EC 1.14.11.1 created 1972]
 
 
EC 1.14.13.239     
Accepted name: carnitine monooxygenase
Reaction: L-carnitine + NAD(P)H + H+ + O2 = (3R)-3-hydroxy-4-oxobutanoate + trimethylamine + NAD(P)+ + H2O
Glossary: (3R)-3-hydroxy-4-oxobutanoate = L-malic semialdehyde
Other name(s): cntAB (gene names); yeaWX (gene names)
Systematic name: L-carnitine,NAD(P)H:oxygen oxidoreductase (trimethylamine-forming)
Comments: The bacterial enzyme is a complex consisting of a reductase and an oxygenase components. The reductase subunit contains a flavin and a plant-type ferredoxin [2Fe-2S] cluster, while the oxygenase subunit is a Rieske-type protein in which a [2Fe-2S] cluster is coordinated by two histidine and two cysteine residues.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Ditullio, D., Anderson, D., Chen, C.S. and Sih, C.J. L-Carnitine via enzyme-catalyzed oxidative kinetic resolution. Bioorg. Med. Chem. 2 (1994) 415–420. [DOI] [PMID: 8000862]
2.  Zhu, Y., Jameson, E., Crosatti, M., Schafer, H., Rajakumar, K., Bugg, T.D. and Chen, Y. Carnitine metabolism to trimethylamine by an unusual Rieske-type oxygenase from human microbiota. Proc. Natl. Acad. Sci. USA 111 (2014) 4268–4273. [DOI] [PMID: 24591617]
3.  Koeth, R.A., Levison, B.S., Culley, M.K., Buffa, J.A., Wang, Z., Gregory, J.C., Org, E., Wu, Y., Li, L., Smith, J.D., Tang, W.H., DiDonato, J.A., Lusis, A.J. and Hazen, S.L. γ-Butyrobetaine is a proatherogenic intermediate in gut microbial metabolism of L-carnitine to TMAO. Cell Metab 20 (2014) 799–812. [DOI] [PMID: 25440057]
[EC 1.14.13.239 created 2017]
 
 
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 1.14.15.7     
Accepted name: choline monooxygenase
Reaction: choline + O2 + 2 reduced ferredoxin + 2 H+ = betaine aldehyde hydrate + H2O + 2 oxidized ferredoxin
Glossary: betaine = glycine betaine = N,N,N-trimethylglycine = N,N,N-trimethylammonioacetate
betaine aldehyde = N,N,N-trimethyl-2-oxoethylammonium
choline = (2-hydroxyethyl)trimethylammonium
Systematic name: choline,reduced-ferredoxin:oxygen oxidoreductase
Comments: The spinach enzyme, which is located in the chloroplast, contains a Rieske-type [2Fe-2S] cluster, and probably also a mononuclear Fe centre. Requires Mg2+. Catalyses the first step of glycine betaine synthesis. In many bacteria, plants and animals, betaine is synthesized in two steps: (1) choline to betaine aldehyde and (2) betaine aldehyde to betaine. Different enzymes are involved in the first reaction. In plants, the reaction is catalysed by this enzyme whereas in animals and many bacteria it is catalysed by either membrane-bound EC 1.1.99.1 (choline dehydrogenase) or soluble EC 1.1.3.17 (choline oxidase) [7]. The enzyme involved in the second step, EC 1.2.1.8 (betaine-aldehyde dehydrogenase), appears to be the same in plants, animals and bacteria. In some bacteria, betaine is synthesized from glycine through the actions of EC 2.1.1.156 (glycine/sarcosine N-methyltransferase) and EC 2.1.1.157 (sarcosine/dimethylglycine N-methyltransferase).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 118390-76-4
References:
1.  Brouquisse, R., Weigel, P., Rhodes, D., Yocum, C.F. and Hanson, A.D. Evidence for a ferredoxin-dependent choline monooxygenase from spinach chloroplast stroma. Plant Physiol. 90 (1989) 322–329. [PMID: 16666757]
2.  Burnet, M., Lafontaine, P.J. and Hanson, A.D. Assay, purification, and partial characterization of choline monooxygenase from spinach. Plant Physiol. 108 (1995) 581–588. [PMID: 12228495]
3.  Rathinasabapathi, B., Burnet, M., Russell, B.L., Gage, D.A., Liao, P., Nye, G.J., Scott, P., Golbeck, J.H. and Hanson, A.D. Choline monooxygenase, an unusual iron-sulfur enzyme catalyzing the first step of glycine betaine synthesis in plants: Prosthetic group characterization and cDNA cloning. Proc. Natl. Acad. Sci. USA 94 (1997) 3454–3458. [DOI] [PMID: 9096415]
4.  Russell, B.L., Rathinasabapathi, B. and Hanson, A.D. Osmotic stress induces expression of choline monooxygenase in sugar beet and amaranth. Plant Physiol. 116 (1998) 859–865. [PMID: 9489025]
5.  Nuccio, M.L., Russell, B.L., Nolte, K.D., Rathinasabapathi, B., Gage, D.A. and Hanson, A.D. Glycine betaine synthesis in transgenic tobacco expressing choline monooxygenase is limited by the endogenous choline supply. Plant J. 16 (1998) 101–110.
6.  Nuccio, M.L., Russell, B.L., Nolte, K.D., Rathinasabapathi, B., Gage, D.A. and Hanson, A.D. The endogenous choline supply limits glycine betaine synthesis in transgenic tobacco expressing choline. Plant J. 16 (1998) 487–496. [DOI] [PMID: 9881168]
7.  Waditee, R., Tanaka, Y., Aoki, K., Hibino, T., Jikuya, H., Takano, J., Takabe, T. and Takabe, T. Isolation and functional characterization of N-methyltransferases that catalyze betaine synthesis from glycine in a halotolerant photosynthetic organism Aphanothece halophytica. J. Biol. Chem. 278 (2003) 4932–4942. [DOI] [PMID: 12466265]
[EC 1.14.15.7 created 2001, modified 2002 (EC 1.14.14.4 created 2000, incorporated 2002), modified 2005, modified 2011]
 
 
EC 1.21.4.2     
Accepted name: glycine reductase
Reaction: acetyl phosphate + NH3 + thioredoxin disulfide + H2O = glycine + phosphate + thioredoxin
For diagram of possible mechanism, click here
Systematic name: acetyl-phosphate ammonia:thioredoxin disulfide oxidoreductase (glycine-forming)
Comments: The reaction is observed only in the direction of glycine reduction. The enzyme from Eubacterium acidaminophilum consists of subunits A, B and C. Subunit B contains selenocysteine and a pyruvoyl group, and is responsible for glycine binding and ammonia release. Subunit A, which also contains selenocysteine, is reduced by thioredoxin, and is needed to convert the carboxymethyl group into a ketene equivalent, in turn used by subunit C to produce acetyl phosphate. Only subunit B distinguishes this enzyme from EC 1.21.4.3 (sarcosine reductase) and EC 1.21.4.4 (betaine reductase).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 39307-24-9
References:
1.  Wagner, M., Sonntag, D., Grimm, R., Pich, A. Eckerskorn, C., Söhling, B. and Andreesen, J.R. Substrate-specific selenoprotein B of glycine reductase from Eubacterium acidaminophilum. Eur. J. Biochem. 260 (1999) 38–49. [DOI] [PMID: 10091582]
2.  Bednarski, B., Andreesen, J.R. and Pich, A. In vitro processing of the proproteins GrdE of protein B of glycine reductase and PrdA of D-proline reductase from Clostridium sticklandii: formation of a pyruvoyl group from a cysteine residue. Eur. J. Biochem. 268 (2001) 3538–3544. [DOI] [PMID: 11422384]
[EC 1.21.4.2 created 2003]
 
 
EC 1.21.4.3     
Accepted name: sarcosine reductase
Reaction: acetyl phosphate + methylamine + thioredoxin disulfide + H2O = N-methylglycine + phosphate + thioredoxin
For diagram of possible reaction mechanism, click here
Glossary: sarcosine = N-methylglycine
Systematic name: acetyl-phosphate methylamine:thioredoxin disulfide oxidoreductase (N-methylglycine-forming)
Comments: The reaction is observed only in the direction of sarcosine reduction. The enzyme from Eubacterium acidaminophilum consists of subunits A, B and C. Subunit B contains selenocysteine and a pyruvoyl group, and is responsible for sarcosine binding and methylamine release. Subunit A, which also contains selenocysteine, is reduced by thioredoxin, and is needed to convert the carboxymethyl group into a ketene equivalent, in turn used by subunit C to produce acetyl phosphate. Only subunit B distinguishes this enzyme from EC 1.21.4.2 (glycine reductase) and EC 1.21.4.4 (betaine reductase).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 125752-88-7
References:
1.  Wagner, M., Sonntag, D., Grimm, R., Pich, A. Eckerskorn, C., Söhling, B. and Andreesen, J.R. Substrate-specific selenoprotein B of glycine reductase from Eubacterium acidaminophilum. Eur. J. Biochem. 260 (1999) 38–49. [DOI] [PMID: 10091582]
2.  Hormann, K. and Andreesen, J.R. Reductive cleavage of sarcosine and betaine by Eubacterium acidaminophilum via enzyme systems different from glycine reductase. Arch. Microbiol. 153 (1989) 50–59.
[EC 1.21.4.3 created 2003]
 
 
EC 1.21.4.4     
Accepted name: betaine reductase
Reaction: acetyl phosphate + trimethylamine + thioredoxin disulfide + H2O = betaine + phosphate + thioredoxin
For diagram of possible mechanism, click here
Glossary: betaine = glycine betaine = N,N,N-trimethylglycine = N,N,N-trimethylammonioacetate
Other name(s): acetyl-phosphate trimethylamine:thioredoxin disulfide oxidoreductase (N,N,N-trimethylglycine-forming)
Systematic name: acetyl-phosphate trimethylamine:thioredoxin disulfide oxidoreductase (betaine-forming)
Comments: The reaction is observed only in the direction of betaine reduction. The enzyme from Eubacterium acidaminophilum consists of subunits A, B and C. Subunit B contains selenocysteine and a pyruvoyl group, and is responsible for betaine binding and trimethylamine release. Subunit A, which also contains selenocysteine, is reduced by thioredoxin, and is needed to convert the carboxymethyl group into a ketene equivalent, in turn used by subunit C to produce acetyl phosphate. Only subunit B distinguishes this enzyme from EC 1.21.4.2 (glycine reductase) and EC 1.21.4.3 (sarcosine reductase).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 125752-87-6
References:
1.  Wagner, M., Sonntag, D., Grimm, R., Pich, A. Eckerskorn, C., Söhling, B. and Andreesen, J.R. Substrate-specific selenoprotein B of glycine reductase from Eubacterium acidaminophilum. Eur. J. Biochem. 260 (1999) 38–49. [DOI] [PMID: 10091582]
2.  Bednarski, B., Andreesen, J.R. and Pich, A. In vitro processing of the proproteins GrdE of protein B of glycine reductase and PrdA of D-proline reductase from Clostridium sticklandii: formation of a pyruvoyl group from a cysteine residue. Eur. J. Biochem. 268 (2001) 3538–3544. [DOI] [PMID: 11422384]
[EC 1.21.4.4 created 2003, modified 2010]
 
 
EC 2.1.1.3     
Accepted name: thetin—homocysteine S-methyltransferase
Reaction: dimethylsulfonioacetate + L-homocysteine = (methylsulfanyl)acetate + L-methionine
Glossary: thetin = sulfobetaine = dimethylsulfonioacetate
Other name(s): dimethylthetin-homocysteine methyltransferase; thetin-homocysteine methylpherase
Systematic name: dimethylsulfonioacetate:L-homocysteine S-methyltransferase
Links to other databases: BRENDA, EXPASY, GTD, KEGG, MetaCyc, CAS registry number: 9029-76-9
References:
1.  Klee, W.A., Richards, H.H. and Cantoni, G.L. The synthesis of methionine by enzymic transmethylation. VII. Existence of two separate homocysteine methylpherases on mammalian liver. Biochim. Biophys. Acta 54 (1961) 157–164. [DOI] [PMID: 14456704]
2.  Maw, G.A. Thetin-homocysteine transmethylase. A preliminary manometric study of the enzyme from rat liver. Biochem. J. 63 (1956) 116–124. [PMID: 13315256]
3.  Maw, G.A. Thetin-homocysteine transmethylase. Some further characteristics of the enzyme from rat liver. Biochem. J. 70 (1958) 168–173. [PMID: 13584318]
[EC 2.1.1.3 created 1961]
 
 
EC 2.1.1.5     
Accepted name: betaine—homocysteine S-methyltransferase
Reaction: betaine + L-homocysteine = dimethylglycine + L-methionine
Glossary: betaine = glycine betaine = N,N,N-trimethylglycine = N,N,N-trimethylammonioacetate
Other name(s): betaine-homocysteine methyltransferase; betaine-homocysteine transmethylase
Systematic name: trimethylammonioacetate:L-homocysteine S-methyltransferase
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9029-78-1
References:
1.  Klee, W.A., Richards, H.H. and Cantoni, G.L. The synthesis of methionine by enzymic transmethylation. VII. Existence of two separate homocysteine methylpherases on mammalian liver. Biochim. Biophys. Acta 54 (1961) 157–164. [DOI] [PMID: 14456704]
[EC 2.1.1.5 created 1961]
 
 
EC 2.1.1.156     
Accepted name: glycine/sarcosine N-methyltransferase
Reaction: 2 S-adenosyl-L-methionine + glycine = 2 S-adenosyl-L-homocysteine + N,N-dimethylglycine (overall reaction)
(1a) S-adenosyl-L-methionine + glycine = S-adenosyl-L-homocysteine + sarcosine
(1b) S-adenosyl-L-methionine + sarcosine = S-adenosyl-L-homocysteine + N,N-dimethylglycine
Glossary: sarcosine = N-methylglycine
Other name(s): ApGSMT; glycine-sarcosine methyltransferase; GSMT; GMT; glycine sarcosine N-methyltransferase; S-adenosyl-L-methionine:sarcosine N-methyltransferase
Systematic name: S-adenosyl-L-methionine:glycine(or sarcosine) N-methyltransferase [sarcosine(or N,N-dimethylglycine)-forming]
Comments: Cells of the oxygen-evolving halotolerant cyanobacterium Aphanocthece halophytica synthesize betaine from glycine by a three-step methylation process. This is the first enzyme and it leads to the formation of either sarcosine or N,N-dimethylglycine, which is further methylated to yield betaine (N,N,N-trimethylglycine) by the action of EC 2.1.1.157, sarcosine/dimethylglycine N-methyltransferase. Differs from EC 2.1.1.20, glycine N-methyltransferase, as it can further methylate the product of the first reaction. Acetate, dimethylglycine and S-adenosyl-L-homocysteine can inhibit the reaction [3].
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 294210-82-5
References:
1.  Nyyssölä, A., Kerovuo, J., Kaukinen, P., von Weymarn, N. and Reinikainen, T. Extreme halophiles synthesize betaine from glycine by methylation. J. Biol. Chem. 275 (2000) 22196–22201. [DOI] [PMID: 10896953]
2.  Nyyssölä, A., Reinikainen, T. and Leisola, M. Characterization of glycine sarcosine N-methyltransferase and sarcosine dimethylglycine N-methyltransferase. Appl. Environ. Microbiol. 67 (2001) 2044–2050. [DOI] [PMID: 11319079]
3.  Waditee, R., Tanaka, Y., Aoki, K., Hibino, T., Jikuya, H., Takano, J., Takabe, T. and Takabe, T. Isolation and functional characterization of N-methyltransferases that catalyze betaine synthesis from glycine in a halotolerant photosynthetic organism Aphanothece halophytica. J. Biol. Chem. 278 (2003) 4932–4942. [DOI] [PMID: 12466265]
[EC 2.1.1.156 created 2005]
 
 
EC 2.1.1.157     
Accepted name: sarcosine/dimethylglycine N-methyltransferase
Reaction: 2 S-adenosyl-L-methionine + sarcosine = 2 S-adenosyl-L-homocysteine + betaine (overall reaction)
(1a) S-adenosyl-L-methionine + sarcosine = S-adenosyl-L-homocysteine + N,N-dimethylglycine
(1b) S-adenosyl-L-methionine + N,N-dimethylglycine = S-adenosyl-L-homocysteine + betaine
Glossary: sarcosine = N-methylglycine
betaine = glycine betaine = N,N,N-trimethylglycine = N,N,N-trimethylammonioacetate
Other name(s): ApDMT; sarcosine-dimethylglycine methyltransferase; SDMT; sarcosine dimethylglycine N-methyltransferase; S-adenosyl-L-methionine:N,N-dimethylglycine N-methyltransferase
Systematic name: S-adenosyl-L-methionine:sarcosine(or N,N-dimethylglycine) N-methyltransferase [N,N-dimethylglycine(or betaine)-forming]
Comments: Cells of the oxygen-evolving halotolerant cyanobacterium Aphanocthece halophytica synthesize betaine from glycine by a three-step methylation process. The first enzyme, EC 2.1.1.156, glycine/sarcosine N-methyltransferase, leads to the formation of either sarcosine or N,N-dimethylglycine, which is further methylated to yield betaine (N,N,N-trimethylglycine) by the action of this enzyme. Both of these enzymes can catalyse the formation of N,N-dimethylglycine from sarcosine [3]. The reactions are strongly inhibited by S-adenosyl-L-homocysteine.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Nyyssölä, A., Kerovuo, J., Kaukinen, P., von Weymarn, N. and Reinikainen, T. Extreme halophiles synthesize betaine from glycine by methylation. J. Biol. Chem. 275 (2000) 22196–22201. [DOI] [PMID: 10896953]
2.  Nyyssölä, A., Reinikainen, T. and Leisola, M. Characterization of glycine sarcosine N-methyltransferase and sarcosine dimethylglycine N-methyltransferase. Appl. Environ. Microbiol. 67 (2001) 2044–2050. [DOI] [PMID: 11319079]
3.  Waditee, R., Tanaka, Y., Aoki, K., Hibino, T., Jikuya, H., Takano, J., Takabe, T. and Takabe, T. Isolation and functional characterization of N-methyltransferases that catalyze betaine synthesis from glycine in a halotolerant photosynthetic organism Aphanothece halophytica. J. Biol. Chem. 278 (2003) 4932–4942. [DOI] [PMID: 12466265]
[EC 2.1.1.157 created 2005, modified 2010]
 
 
EC 2.1.1.161     
Accepted name: dimethylglycine N-methyltransferase
Reaction: S-adenosyl-L-methionine + N,N-dimethylglycine = S-adenosyl-L-homocysteine + betaine
Glossary: betaine = glycine betaine = N,N,N-trimethylglycine = N,N,N-trimethylammonioacetate
Other name(s): BsmB; DMT
Systematic name: S-adenosyl-L-methionine:N,N-dimethylglycine N-methyltransferase (betaine-forming)
Comments: This enzyme, from the marine cyanobacterium Synechococcus sp. WH8102, differs from EC 2.1.1.157, sarcosine/dimethylglycine N-methyltransferase in that it cannot use sarcosine as an alternative substrate [1]. Betaine is a ’compatible solute’ that enables cyanobacteria to cope with osmotic stress by maintaining a positive cellular turgor.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Lu, W.D., Chi, Z.M. and Su, C.D. Identification of glycine betaine as compatible solute in Synechococcus sp. WH8102 and characterization of its N-methyltransferase genes involved in betaine synthesis. Arch. Microbiol. 186 (2006) 495–506. [DOI] [PMID: 17019606]
[EC 2.1.1.161 created 2007]
 
 
EC 2.1.1.162     
Accepted name: glycine/sarcosine/dimethylglycine N-methyltransferase
Reaction: 3 S-adenosyl-L-methionine + glycine = 3 S-adenosyl-L-homocysteine + betaine (overall reaction)
(1a) S-adenosyl-L-methionine + glycine = S-adenosyl-L-homocysteine + sarcosine
(1b) S-adenosyl-L-methionine + sarcosine = S-adenosyl-L-homocysteine + N,N-dimethylglycine
(1c) S-adenosyl-L-methionine + N,N-dimethylglycine = S-adenosyl-L-homocysteine + betaine
Glossary: sarcosine = N-methylglycine
betaine = glycine betaine = N,N,N-trimethylglycine = N,N,N-trimethylammonioacetate
Other name(s): GSDMT; glycine sarcosine dimethylglycine N-methyltransferase
Systematic name: S-adenosyl-L-methionine:glycine(or sarcosine or N,N-dimethylglycine) N-methyltransferase [sarcosine(or N,N-dimethylglycine or betaine)-forming]
Comments: Unlike EC 2.1.1.156 (glycine/sarcosine N-methyltransferase), EC 2.1.1.157 (sarcosine/dimethylglycine N-methyltransferase) and EC 2.1.1.161 (dimethylglycine N-methyltransferase), this enzyme, from the halophilic methanoarchaeon Methanohalophilus portucalensis, can methylate glycine and all of its intermediates to form the compatible solute betaine [1].
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Lai, M.C., Wang, C.C., Chuang, M.J., Wu, Y.C. and Lee, Y.C. Effects of substrate and potassium on the betaine-synthesizing enzyme glycine sarcosine dimethylglycine N-methyltransferase from a halophilic methanoarchaeon Methanohalophilus portucalensis. Res. Microbiol. 157 (2006) 948–955. [DOI] [PMID: 17098399]
[EC 2.1.1.162 created 2007]
 
 
EC 2.1.1.269     
Accepted name: dimethylsulfoniopropionate demethylase
Reaction: S,S-dimethyl-β-propiothetin + tetrahydrofolate = 3-(methylsulfanyl)propanoate + 5-methyltetrahydrofolate
For diagram of 3-(dimethylsulfonio)propanoate metabolism, click here
Glossary: S,S-dimethyl-β-propiothetin = 3-(S,S-dimethylsulfonio)propanoate
Other name(s): dmdA (gene name); dimethylsulfoniopropionate-dependent demethylase A
Systematic name: S,S-dimethyl-β-propiothetin:tetrahydrofolate S-methyltransferase
Comments: The enzyme from the marine bacteria Pelagibacter ubique and Ruegeria pomeroyi are specific towards S,S-dimethyl-β-propiothetin. They do not demethylate glycine-betaine [1,2].
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Jansen, M. and Hansen, T.A. Tetrahydrofolate serves as a methyl acceptor in the demethylation of dimethylsulfoniopropionate in cell extracts of sulfate-reducing bacteria. Arch. Microbiol. 169 (1998) 84–87. [PMID: 9396840]
2.  Reisch, C.R., Moran, M.A. and Whitman, W.B. Dimethylsulfoniopropionate-dependent demethylase (DmdA) from Pelagibacter ubique and Silicibacter pomeroyi. J. Bacteriol. 190 (2008) 8018–8024. [DOI] [PMID: 18849431]
3.  Schuller, D.J., Reisch, C.R., Moran, M.A., Whitman, W.B. and Lanzilotta, W.N. Structures of dimethylsulfoniopropionate-dependent demethylase from the marine organism Pelagibacter ubique. Protein Sci. 21 (2012) 289–298. [DOI] [PMID: 22162093]
[EC 2.1.1.269 created 2013]
 
 
EC 2.1.1.376     
Accepted name: glycine betaine—corrinoid protein Co-methyltransferase
Reaction: glycine betaine + a [Co(I) glycine betaine-specific corrinoid protein] = N,N-dimethylglycine + a [methyl-Co(III) glycine betaine-specific corrinoid protein]
Other name(s): mtgB (gene name); glycine betaine methyltransferase
Systematic name: glycine betaine:[Co(I) glycine betaine-specific corrinoid protein] Co-methyltransferase
Comments: The enzyme, which catalyses the transfer of a methyl group from glycine betaine to a glycine betaine-specific corrinoid protein (MtgC), is involved in methanogenesis from glycine betaine in some methanogenic archaea, and in glycine betaine degradation in some bacteria. Unlike similar enzymes involved in methanogenesis from methylated C1 compounds, this enzyme does not contain the unusual amino acid L-pyrrolysine.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Ticak, T., Kountz, D.J., Girosky, K.E., Krzycki, J.A. and Ferguson, D.J., Jr. A nonpyrrolysine member of the widely distributed trimethylamine methyltransferase family is a glycine betaine methyltransferase. Proc. Natl. Acad. Sci. USA 111 (2014) E4668–E4676. [DOI] [PMID: 25313086]
2.  Creighbaum, A.J., Ticak, T., Shinde, S., Wang, X. and Ferguson, D.J., Jr. Examination of the glycine betaine-dependent methylotrophic methanogenesis pathway: insights into anaerobic quaternary amine methylotrophy. Front. Microbiol. 10:2572 (2019). [DOI] [PMID: 31787957]
[EC 2.1.1.376 created 2021]
 
 
EC 2.1.1.377     
Accepted name: [methyl-Co(III) glycine betaine-specific corrinoid protein]—coenzyme M methyltransferase
Reaction: a [methyl-Co(III) glycine betaine-specific corrinoid protein] + CoM = methyl-CoM + a [Co(I) glycine betaine-specific corrinoid protein]
Other name(s): mtaA (gene name)
Systematic name: methylated glycine betaine-specific corrinoid protein:CoM methyltransferase
Comments: The enzyme, which is involved in methanogenesis from glycine betaine, catalyses the transfer of a methyl group bound to the cobalt cofactor of glycine betaine-specific corrinoid protein to coenzyme M, forming the substrate for EC 2.8.4.1, coenzyme-B sulfoethylthiotransferase, which catalyses the final step in methanogenesis. The enzyme from the methanogenic archaeon Methanolobus vulcani B1d can also catalyse the activity of EC 2.1.1.246, [methyl-Co(III) methanol-specific corrinoid protein]—coenzyme M methyltransferase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Creighbaum, A.J., Ticak, T., Shinde, S., Wang, X. and Ferguson, D.J., Jr. Examination of the glycine betaine-dependent methylotrophic methanogenesis pathway: insights into anaerobic quaternary amine methylotrophy. Front. Microbiol. 10:2572 (2019). [DOI] [PMID: 31787957]
[EC 2.1.1.377 created 2021]
 
 
EC 2.1.1.378     
Accepted name: [methyl-Co(III) glycine betaine-specific corrinoid protein]—tetrahydrofolate methyltransferase
Reaction: a [methyl-Co(III) glycine betaine-specific corrinoid protein] + tetrahydrofolate = a [Co(I) glycine betaine-specific corrinoid protein] + 5-methyltetrahydrofolate
Other name(s): mtgA (gene name); DSY3157 (locus name)
Systematic name: [methyl-Co(III) glycine betaine-specific corrinoid protein]:tetrahydrofolate N-methyltransferase
Comments: This enzyme, characterized from the anaerobic bacterium Desulfitobacterium hafniense Y51, catalyses a similar reaction to that of EC 2.1.1.258, 5-methyltetrahydrofolate—corrinoid/iron-sulfur protein Co-methyltransferase, but in the opposite direction, transferring a methyl group from a methylated corrinoid protein to tetrahydrofolate. The corrinoid protein is specifically methylated by EC 2.1.1.376, glycine betaine—corrinoid protein Co-methyltransferase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Ticak, T., Kountz, D.J., Girosky, K.E., Krzycki, J.A. and Ferguson, D.J., Jr. A nonpyrrolysine member of the widely distributed trimethylamine methyltransferase family is a glycine betaine methyltransferase. Proc. Natl. Acad. Sci. USA 111 (2014) E4668–E4676. [DOI] [PMID: 25313086]
[EC 2.1.1.378 created 2021]
 
 
EC 2.8.3.21     
Accepted name: L-carnitine CoA-transferase
Reaction: (1) (E)-4-(trimethylammonio)but-2-enoyl-CoA + L-carnitine = (E)-4-(trimethylammonio)but-2-enoate + L-carnitinyl-CoA
(2) 4-trimethylammoniobutanoyl-CoA + L-carnitine = 4-trimethylammoniobutanoate + L-carnitinyl-CoA
Glossary: L-carnitine = (3R)-3-hydroxy-4-(trimethylammonio)butanoate
(E)-4-(trimethylammonio)but-2-enoate = crotonobetaine
4-trimethylammoniobutanoate = γ-butyrobetaine
Other name(s): CaiB; crotonobetainyl/γ-butyrobetainyl-CoA:carnitine CoA-transferase
Systematic name: (E)-4-(trimethylammonio)but-2-enoyl-CoA:L-carnitine CoA-transferase
Comments: The enzyme is found in gammaproteobacteria such as Proteus sp. and Escherichia coli. It has similar activity with both substrates.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Engemann, C., Elssner, T. and Kleber, H.P. Biotransformation of crotonobetaine to L-(–)-carnitine in Proteus sp. Arch. Microbiol. 175 (2001) 353–359. [PMID: 11409545]
2.  Elssner, T., Engemann, C., Baumgart, K. and Kleber, H.P. Involvement of coenzyme A esters and two new enzymes, an enoyl-CoA hydratase and a CoA-transferase, in the hydration of crotonobetaine to L-carnitine by Escherichia coli. Biochemistry 40 (2001) 11140–11148. [DOI] [PMID: 11551212]
3.  Stenmark, P., Gurmu, D. and Nordlund, P. Crystal structure of CaiB, a type-III CoA transferase in carnitine metabolism. Biochemistry 43 (2004) 13996–14003. [DOI] [PMID: 15518548]
4.  Engemann, C., Elssner, T., Pfeifer, S., Krumbholz, C., Maier, T. and Kleber, H.P. Identification and functional characterisation of genes and corresponding enzymes involved in carnitine metabolism of Proteus sp. Arch. Microbiol. 183 (2005) 176–189. [DOI] [PMID: 15731894]
5.  Rangarajan, E.S., Li, Y., Iannuzzi, P., Cygler, M. and Matte, A. Crystal structure of Escherichia coli crotonobetainyl-CoA: carnitine CoA-transferase (CaiB) and its complexes with CoA and carnitinyl-CoA. Biochemistry 44 (2005) 5728–5738. [DOI] [PMID: 15823031]
[EC 2.8.3.21 created 2014]
 
 
EC 3.6.3.32      
Transferred entry: quaternary-amine-transporting ATPase. Now EC 7.6.2.9, quaternary-amine-transporting ATPase
[EC 3.6.3.32 created 2000, deleted 2018]
 
 
EC 4.2.1.149     
Accepted name: crotonobetainyl-CoA hydratase
Reaction: L-carnitinyl-CoA = (E)-4-(trimethylammonio)but-2-enoyl-CoA + H2O
Glossary: L-carnitinyl-CoA = (3R)-3-hydroxy-4-(trimethylammonio)butanoyl-CoA
(E)-4-(trimethylammonio)but-2-enoyl-CoA = crotonobetainyl-CoA
Other name(s): CaiD; L-carnityl-CoA dehydratase
Systematic name: L-carnitinyl-CoA hydro-lyase [(E)-4-(trimethylammonio)but-2-enoyl-CoA-forming]
Comments: The enzyme is also able to use crotonyl-CoA as substrate, with low efficiency [2].
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Engemann, C., Elssner, T. and Kleber, H.P. Biotransformation of crotonobetaine to L-(–)-carnitine in Proteus sp. Arch. Microbiol. 175 (2001) 353–359. [PMID: 11409545]
2.  Elssner, T., Engemann, C., Baumgart, K. and Kleber, H.P. Involvement of coenzyme A esters and two new enzymes, an enoyl-CoA hydratase and a CoA-transferase, in the hydration of crotonobetaine to L-carnitine by Escherichia coli. Biochemistry 40 (2001) 11140–11148. [DOI] [PMID: 11551212]
3.  Engemann, C., Elssner, T., Pfeifer, S., Krumbholz, C., Maier, T. and Kleber, H.P. Identification and functional characterisation of genes and corresponding enzymes involved in carnitine metabolism of Proteus sp. Arch. Microbiol. 183 (2005) 176–189. [DOI] [PMID: 15731894]
[EC 4.2.1.149 created 2014]
 
 
EC 5.1.1.22     
Accepted name: 4-hydroxyproline betaine 2-epimerase
Reaction: (1) trans-4-hydroxy-L-proline betaine = cis-4-hydroxy-D-proline betaine
(2) L-proline betaine = D-proline betaine
Glossary: trans-4-hydroxy-L-proline betaine = (2S,4R)-4-hydroxy-1,1-dimethylpyrrolidinium-2-carboxylate
cis-4-hydroxy-D-proline betaine = (2R,4R)-4-hydroxy-1,1-dimethylpyrrolidinium-2-carboxylate
L-proline betaine = (2S)-1,1-dimethylpyrrolidinium-2-carboxylate
D-proline betaine = (2R)-1,1-dimethylpyrrolidinium-2-carboxylate
Other name(s): hpbD (gene name); Hyp-B 2-epimerase; (4R)-4-hydroxyproline betaine 2-epimerase
Systematic name: 4-hydroxyproline betaine 2-epimerase
Comments: The enzyme, characterized from the bacteria Pelagibaca bermudensis and Paracoccus denitrificans, specifically catalyses racemization of trans-4-hydroxy-L-proline betaine and L-proline betaine at the C-2 position.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Zhao, S., Kumar, R., Sakai, A., Vetting, M.W., Wood, B.M., Brown, S., Bonanno, J.B., Hillerich, B.S., Seidel, R.D., Babbitt, P.C., Almo, S.C., Sweedler, J.V., Gerlt, J.A., Cronan, J.E. and Jacobson, M.P. Discovery of new enzymes and metabolic pathways by using structure and genome context. Nature 502 (2013) 698–702. [DOI] [PMID: 24056934]
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 5.1.1.22 created 2017]
 
 
EC 6.2.1.48     
Accepted name: carnitine—CoA ligase
Reaction: ATP + L-carnitine + CoA = AMP + diphosphate + L-carnitinyl-CoA
Glossary: carnitine = 3-hydroxy-4-(trimethylammonio)butanoate
crotonobetaine = (E)-4-(trimethylammonio)but-2-enoate
γ-butyrobetaine = 4-(trimethylammonio)butanoate
Other name(s): caiC (gene name)
Systematic name: L-carnitine:CoA ligase (AMP-forming)
Comments: The enzyme, originally characterized from the bacterium Escherichia coli, can catalyse the transfer of CoA to L-carnitine, crotonobetaine and γ-butyrobetaine. In vitro the enzyme also exhibits the activity of EC 2.8.3.21, L-carnitine CoA-transferase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Eichler, K., Bourgis, F., Buchet, A., Kleber, H.P. and Mandrand-Berthelot, M.A. Molecular characterization of the cai operon necessary for carnitine metabolism in Escherichia coli. Mol. Microbiol. 13 (1994) 775–786. [DOI] [PMID: 7815937]
2.  Bernal, V., Arense, P., Blatz, V., Mandrand-Berthelot, M.A., Canovas, M. and Iborra, J.L. Role of betaine:CoA ligase (CaiC) in the activation of betaines and the transfer of coenzyme A in Escherichia coli. J. Appl. Microbiol. 105 (2008) 42–50. [DOI] [PMID: 18266698]
[EC 6.2.1.48 created 2017]
 
 
EC 7.6.2.9     
Accepted name: ABC-type quaternary amine transporter
Reaction: ATP + H2O + quaternary amine-[quaternary amine-binding protein][side 1] = ADP + phosphate + quaternary amine[side 2] + [quaternary amine-binding protein][side 1]
Other name(s): glycine betaine ABC transporter; ProVWX; quaternary-amine ABC transporter; quaternary-amine-transporting ATPase (ambiguous)
Systematic name: ATP phosphohydrolase (ABC-type, quaternary-amine-importing)
Comments: An ATP-binding cassette (ABC) type transporter, characterized by the presence of two similar ATP-binding domains/proteins and two integral membrane domains/proteins. Does not undergo phosphorylation during the transport process. A bacterial enzyme that interacts with an extracytoplasmic substrate binding protein and mediates the high affinity uptake of quaternary amine derivatives.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Kuan, G., Dassa, E., Saurin, N., Hofnung, M. and Saier, M.H., Jr. Phylogenetic analyses of the ATP-binding constituents of bacterial extracytoplasmic receptor-dependent ABC-type nutrient uptake permeases. Res. Microbiol. 146 (1995) 271–278. [DOI] [PMID: 7569321]
2.  Kempf, B., Gade, J. and Bremer, E. Lipoprotein from the osmoregulated ABC transport system OpuA of Bacillus subtilis: purification of the glycine betaine binding protein and characterization of a functional lipidless mutant. J. Bacteriol. 179 (1997) 6213–6220. [DOI] [PMID: 9335265]
3.  Saier, M.H., Jr. Molecular phylogeny as a basis for the classification of transport proteins from bacteria, archaea and eukarya. Adv. Microb. Physiol. 40 (1998) 81–136. [PMID: 9889977]
[EC 7.6.2.9 created 2000 as EC 3.6.3.32, transferred 2018 to EC 7.6.2.9]
 
 


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