An asterisk before 'EC' indicates that this is an amendment to an existing enzyme rather than a new enzyme entry.
Accepted name: 2-hydroxymethylglutarate dehydrogenase
Reaction: (S)-2-hydroxymethylglutarate + NAD+ = 2-formylglutarate + NADH + H+
For diagram click here.
Other name(s): HgD
Systematic name: (S)-2-hydroxymethylglutarate:NAD+ oxidoreductase
Comments: NADP+ cannot replace NAD+. Forms part of the nicotinate-fermentation catabolism pathway in Eubacterium barkeri. Other enzymes involved in this pathway are EC 1.17.1.5 (nicotinate dehydrogenase), EC 1.3.7.1 (6-hydroxynicotinate reductase), EC 3.5.2.18 (enamidase), EC 5.4.99.4 (2-methyleneglutarate mutase), EC 5.3.3.6 (methylitaconate Δ-isomerase), EC 4.2.1.85 (dimethylmaleate hydratase) and EC 4.1.3.32 (2,3-dimethylmalate lyase).
References:
1. Alhapel, A., Darley, D.J., Wagener, N., Eckel, E., Elsner, N. and Pierik, A.J. Molecular and functional analysis of nicotinate catabolism in Eubacterium barkeri. Proc. Natl. Acad. Sci. USA 103 (2006) 12341-12346. [PMID: 16894175]
Accepted name: L-gulonolactone oxidase
Reaction: (1) L-gulono-1,4-lactone + O2 = L-xylo-hex-2-ulono-1,4-lactone + H2O2
(2) L-xylo-hex-2-ulono-1,4-lactone = L-ascorbate (spontaneous)
For diagram click here.
Other name(s): L-gulono-γ-lactone: O2 oxidoreductase; L-gulono-γ-lactone oxidase; L-gulono-γ-lactone:oxidoreductase; GLO
Systematic name: L-gulono-1,4-lactone:oxygen 3-oxidoreductase
Comments: A microsomal flavoprotein (FAD). The product spontaneously isomerizes to L-ascorbate. While most higher animals can synthesize asborbic acid, primates and guinea pigs cannot [3].
Links to other databases: BRENDA, ERGO, EXPASY, KEGG, CAS registry number: 9028-78-8
References:
1. Isherwood, F.A., Mapson, L.W. and Chen, Y.T. Synthesis of L-ascorbic acid in rat liver homogenates. Conversion of L-gulono- and L-galactono-γ-lactone and the respective acids into L-ascorbic acid. Biochem. J. 76 (1960) 157-171. [PMID: 14405898]
2. Kiuchi, K., Noshikimi, M. and Yagi, K. Purification and characterization of L-gulonolactone oxidase from chicken kidney microsomes. Biochemistry 21 (1982) 5076-5082. [PMID: 7138847]
3. Nishikimi, M., Fukuyama, R., Minoshima, S., Shimizu, N. and Yagi, K. Cloning and chromosomal mapping of the human nonfunctional gene for L-gulono-γ-lactone oxidase, the enzyme for L-ascorbic acid biosynthesis missing in man. J. Biol. Chem. 269 (1994) 13685-13688. [PMID: 8175804]
4. Chatterjee, I.B., Chatterjee, G.C., Ghosh, N.C. and Guha, B.C. Identification of 2-keto-L-gulonolactone as an intermediate in the biosynthesis of L-ascorbic acid. Naturwissenschaften 46 (1959) 475 only.
Accepted name: (S)-mandelate dehydrogenase
Reaction: (S)-2-hydroxy-2-phenylacetate + acceptor = 2-oxo-2-phenylacetate + reduced acceptor
For diagram click here.
Glossary: (S)-mandelate = (S)-2-hydroxy-2-phenylacetate
2-oxo-2-phenylacetate = benzoylformate
Other name(s): MDH
Systematic name: (S)-2-hydroxy-2-phenylacetate:acceptor 2-oxidoreductase
Comments: This enzyme is a member of the FMN-dependent α-hydroxy-acid oxidase/dehydrogenase family [1]. While all enzymes of this family oxidize the (S)-enantiomer of an α-hydroxy acid to an α-oxo acid, the ultimate oxidant (oxygen, intramolecular heme or some other acceptor) depends on the particular enzyme. This enzyme transfers the electron pair from FMNH2 to a component of the electron transport chain, most probably ubiquinone [1,2]. It is part of a metabolic pathway in Pseudomonads that allows these organisms to utilize mandelic acid, derivatized from the common soil metabolite amygdalin, as the sole source of carbon and energy [2]. The enzyme has a large active-site pocket and preferentially binds substrates with longer sidechains, e.g. 2-hydroxyoctanoate rather than 2-hydroxybutyrate [1]. It also prefers substrates that, like (S)-mandelate, have β unsaturation, e.g. (indol-3-yl)glycolate compared with (indol-3-yl)lactate [1]. Esters of mandelate, such as methyl (S)-mandelate, are also substrates [3].
References:
1. Lehoux, I.E. and Mitra, B. (S)-Mandelate dehydrogenase from Pseudomonas putida: mechanistic studies with alternate substrates and pH and kinetic isotope effects. Biochemistry 38 (1999) 5836-5848. [PMID: 10231535]
2. Dewanti, A.R., Xu, Y. and Mitra, B. Role of glycine 81 in (S)-mandelate dehydrogenase from Pseudomonas putida in substrate specificity and oxidase activity. Biochemistry 43 (2004) 10692-10700. [PMID: 15311930]
3. Dewanti, A.R., Xu, Y. and Mitra, B. Esters of mandelic acid as substrates for (S)-mandelate dehydrogenase from Pseudomonas putida: implications for the reaction mechanism. Biochemistry 43 (2004) 1883-1890. [PMID: 14967029]
[EC 1.1.3.24 Transferred entry: L-galactonolactone oxidase. Now EC 1.3.3.12, L-galactonolactone oxidase. The enzyme had been incorrectly classified as acting upon a CH-OH donor rather than a CH-CH donor. (EC 1.1.3.24 created 1984, deleted 2006)]
Accepted name: L-galactonolactone dehydrogenase
Reaction: (1) L-galactono-1,4-lactone + 2 ferricytochrome c = L-ascorbate + 2 ferrocytochrome c
(2) L-ascorbate + 2 ferricytochrome c = L-dehydroascorbate + 2 ferrocytochrome c (spontaneous)
Other name(s): galactonolactone dehydrogenase; L-galactono-γ-lactone dehydrogenase; L-galactono-γ-lactone:ferricytochrome-c oxidoreductase; GLDHase; GLDase
Systematic name: L-galactono-1,4-lactone:ferricytochrome-c oxidoreductase
Comments: This enzyme catalyses the final step in the biosynthesis of L-ascorbic acid in higher plants and in nearly all higher animals with the exception of primates and some birds [5]. The enzyme is very specific for its substrate L-galactono-1,4-lactone as D-galactono-γ-lactone, D-gulono-γ-lactone, L-gulono-γ-lactone, D-erythronic-γ-lactone, D-xylonic-γ-lactone, L-mannono-γ-lactone, D-galactonate, D-glucuronate and D-gluconate are not substrates [5]. FAD, NAD+, NADP+ and O2 (cf. EC 1.3.3.12, L-galactonolactone oxidase) cannot act as electron acceptor [5].
Links to other databases: BRENDA, ERGO, EXPASY, KEGG, CAS registry number: 9029-02-1
References:
1. Mapson, L.W. and Breslow, E. Properties of partially purified L-galactono-γ-lactone dehydrogenase. Biochem. J. 65 (1957) 29 only.
2. Mapson, L.W., Isherwood, F.A. and Chen, Y.T. Biological synthesis of L-ascorbic acid: the conversion of L-galactono-γ-lactone into L-ascorbic acid by plant mitochondria. Biochem. J. 56 (1954) 21-28. [PMID: 13126087]
3. Isherwood, F.A., Chen, Y.T. and Mapson, L.W. Synthesis of L-ascorbic acid in plants and animals. Biochem. J. 56 (1954) 1-15. [PMID: 13126085]
4. Ôba, K., Ishikawa, S., Nishikawa, M., Mizuno, H. and Yamamoto, T. Purification and properties of L-galactono-γ-lactone dehydrogenase, a key enzyme for ascorbic acid biosynthesis, from sweet potato roots. J. Biochem. (Tokyo) 117 (1995) 120-124. [PMID: 7775377]
5. Østergaard, J., Persiau, G., Davey, M.W., Bauw, G. and Van Montagu, M. Isolation of a cDNA coding for L-galactono-γ-lactone dehydrogenase, an enzyme involved in the biosynthesis of ascorbic acid in plants. Purification, characterization, cDNA cloning, and expression in yeast. J. Biol. Chem. 272 (1997) 30009-30016. [PMID: 9374475]
Accepted name: L-galactonolactone oxidase
Reaction: L-galactono-1,4-lactone + O2 = L-ascorbate + H2O2
Other name(s): L-galactono-1,4-lactone oxidase
Systematic name: L-galactono-1,4-lactone:oxygen 3-oxidoreductase
Comments: A flavoprotein. Acts on the 1,4-lactones of L-galactonic, D-altronic, L-fuconic, D-arabinic and D-threonic acids; not identical with EC 1.1.3.8 L-gulonolactone oxidase. (cf. EC 1.3.2.3 galactonolactone dehydrogenase).
Links to other databases: BRENDA, ERGO, EXPASY, KEGG, CAS registry number:
References:
1. Bleeg, H.S. and Christensen, F. Biosynthesis of ascorbate in yeast. Purification of L-galactono-1,4-lactone oxidase with properties different from mammalian L-gulonolactone oxidase. Eur. J. Biochem. 127 (1982) 391-396. [PMID: 6754380]
Accepted name: L-lysine 6-oxidase
Reaction: L-lysine + O2 + H2O = 2-aminoadipate 6-semialdehyde + H2O2 + NH3
Glossary: 2-aminoadipate 6-semialdehyde = allysine = (S)-2-amino-6-oxohexanoate
Other name(s): L-lysine-ε-oxidase; Lod; LodA; marinocine
Systematic name: L-lysine:oxygen 6-oxidoreductase (deaminating)
Comments: Differs from EC 1.4.3.13, protein-lysine 6-oxidase, by using free L-lysine rather than the protein-bound form. 2-N-Acetyl-L-lysine is also a substrate, but 6-N-acetyl-L-lysine, which has an acetyl group at position 6, is not a substrate. Also acts on L-ornithine, D-lysine and 4-hydroxy-L-lysine, but more slowly. The amines cadaverine and putrescine are not substrates [2].
References:
1. Lucas-Elío, P., Gómez, D., Solano, F. and Sanchez-Amat, A. The antimicrobial activity of marinocine, synthesized by Marinomonas mediterranea, is due to hydrogen peroxide generated by its lysine oxidase activity. J. Bacteriol. 188 (2006) 2493-2501. [PMID: 16547036]
2. Gómez, D., Lucas-Elío, P., Sanchez-Amat, A. and Solano, F. A novel type of lysine oxidase: L-lysine-ε-oxidase. Biochim. Biophys. Acta 1764 (2006) 1577-1585. [PMID: 17030025]
Accepted name: nitroalkane oxidase
Reaction: a nitroalkane + H2O + O2 = an aldehyde or ketone + nitrite + H2O2
Other name(s): nitroethane oxidase; NAO; nitroethane:oxygen oxidoreductase
Systematic name: nitroalkane:oxygen oxidoreductase
Comments: Has an absolute requirement for FAD [4]. While nitroethane may be the physiological substrate [2], the enzyme also acts on several other nitroalkanes, including 1-nitropropane, 2-nitropropane, 1-nitrobutane, 1-nitropentane, 1-nitrohexane, nitrocyclohexane and some nitroalkanols [4]. Differs from EC 1.13.11.32, 2-nitropropane dioxygenase, in that the preferred substrates are neutral nitroalkanes rather than anionic nitronates [4].
Links to other databases: BRENDA, ERGO, EXPASY, KEGG, CAS registry number: 9029-36-1
References:
1. Little, H.N. Oxidation of nitroethane by extracts from Neurospora. J. Biol. Chem. 193 (1951) 347-358. [PMID: 14907722]
2. Kido, T., Hashizume, K. and Soda, K. Purification and properties of nitroalkane oxidase from Fusarium oxysporum. J. Bacteriol. 133 (1978) 53-58. [PMID: 22538]
3. Daubner, S.C., Gadda, G., Valley, M.P. and Fitzpatrick, P.F. Cloning of nitroalkane oxidase from Fusarium oxysporum identifies a new member of the acyl-CoA dehydrogenase superfamily. Proc. Natl. Acad. Sci. USA 99 (2002) 2702-2707. [PMID: 11867731]
4. Fitzpatrick, P.F., Orville, A.M., Nagpal, A. and Valley, M.P. Nitroalkane oxidase, a carbanion-forming flavoprotein homologous to acyl-CoA dehydrogenase. Arch. Biochem. Biophys. 433 (2005) 157-165. [PMID: 15581574]
5. Valley, M.P., Tichy, S.E. and Fitzpatrick, P.F. Establishing the kinetic competency of the cationic imine intermediate in nitroalkane oxidase. J. Am. Chem. Soc. 127 (2005) 2062-2066. [PMID: 15713081]
Accepted name: 2-nitropropane dioxygenase
Reaction: 2 2-nitropropane + O2 = 2 acetone + 2 nitrite
Systematic name: 2-nitropropane:oxygen 2-oxidoreductase
Comments: While the enzyme from the fungus Neurospora crassa contains non-covalently bound FMN as the cofactor, that from the yeast Williopsis mrakii contains FAD [2]. This enzyme differs from EC 1.7.3.1, nitroalkane oxidase, in that the preferred substrates are anionic nitronates rather than neutral nitroalkanes [2,3]. The enzyme has broad substrate specificity that is independent of substrate size [2,3]. Some other nitroalkanes, including nitroethane, 1-nitropropane and 3-nitropentan-2-ol, can act as donors, but more slowly.
Links to other databases: BRENDA, ERGO, EXPASY, KEGG, UM-BBD, CAS registry number: 65802-82-6, 61584-55-2
References:
1. Kido, T., Soda, K., Suzuki, T. and Asada, K. A new oxygenase, 2-nitropropane dioxygenase of Hansenula mrakii. Enzymologic and spectrophotometric properties. J. Biol. Chem. 251 (1976) 6994-7000. [PMID: 11214]
2. Ha, J.Y., Min, J.Y., Lee, S.K., Kim, H.S., Kim do, J., Kim, K.H., Lee, H.H., Kim, H.K., Yoon, H.J. and Suh, S.W. Crystal structure of 2-nitropropane dioxygenase complexed with FMN and substrate. Identification of the catalytic base. J. Biol. Chem. 281 (2006) 18660-18667. [PMID: 16682407]
3. Francis, K., Russell, B. and Gadda, G. Involvement of a flavosemiquinone in the enzymatic oxidation of nitroalkanes catalyzed by 2-nitropropane dioxygenase. J. Biol. Chem. 280 (2005) 5195-5204. [PMID: 15582992]
Accepted name: 5-hydroxyfuranocoumarin 5-O-methyltransferase
Reaction: (1) S-adenosyl-L-methionine + a 5-hydroxyfurocoumarin = S-adenosyl-L-homocysteine + a 5- methoxyfurocoumarin (general reaction)
(2) S-adenosyl-L-methionine + bergaptol = S-adenosyl-L-homocysteine + bergapten
For diagram click here.
Glossary: bergaptol = 5-hydroxypsoralen
O-methylbergaptol = bergapten = 5-methoxypsoralen
Other name(s): furanocoumarin 5-methyltransferase; furanocoumarin 5-O-methyltransferase; bergaptol 5-O-methyltransferase; bergaptol O-methyltransferase; bergaptol methyltransferase; S-adenosyl-L-methionine:bergaptol O-methyltransferase; BMT; S-adenosyl-L-methionine:5-hydroxyfuranocoumarin 5-O-methyltransferase
Systematic name: S-adenosyl-L-methionine:5-hydroxyfurocoumarin 5-O-methyltransferase
Comments: Converts bergaptol into bergapten, which has therapeutic potential in the treatment of psoriasis as it has photosensitizing and antiproliferative activities [4]. The enzyme methylates the 5-hydroxy group of some hydroxy- and methylcoumarins, but has little activity on non-coumarin phenols [1]. Caffeate, 5-hydroxyferulate and daphnetin are not substrates [4]. Cu2+, Zn2+ and Co2+ cause enzyme inhibition [4]. (see also EC 2.1.1.70, 8-hydroxyfuranocoumarin 8-O-methyltransferase)
Links to other databases: BRENDA, EXPASY, KEGG, ERGO, CAS registry number: 67339-12-2
References:
1. Thompson, H.J., Sharma, S.K. and Brown, S.A. O-Methyltransferases of furanocoumarin biosynthesis. Arch. Biochem. Biophys. 188 (1978) 272-281. [PMID: 28084]
2. Sharma, S.K., Garrett, J.M. and Brown, S.A. Separation of the S-adenosylmethionine: 5- and 8-hydroxyfuranocoumarin O-methyltransferases of Ruta graveolens L. by general ligand affinity chromatography. Z. Naturforsch. [C] 34C (1979) 387-391. [PMID: 156999]
3. Hauffe, K.D., Hahlbrock, K. and Scheel, D. Elicitor-stimulated furanocoumarin biosynthesis in cultured parsley cells - S-adenosyl-L-methionine-bergaptol and S-adenosyl-L-methionine-xanthotoxol O-methyltransferases. Z. Naturforsch. C: Biosci. 41 (1986) 228-239.
4. Hehmann, M., Lukacin, R., Ekiert, H. and Matern, U. Furanocoumarin biosynthesis in Ammi majus L. Cloning of bergaptol O-methyltransferase. Eur. J. Biochem. 271 (2004) 932-940. [PMID: 15009205]
Accepted name: 8-hydroxyfuranocoumarin 8-O-methyltransferase
Reaction: (1) S-adenosyl-L-methionine + an 8-hydroxyfurocoumarin = S-adenosyl-L-homocysteine + an 8-methoxyfurocoumarin (general reaction)
(2) S-adenosyl-L-methionine + xanthotoxol = S-adenosyl-L-homocysteine + xanthotoxin
For diagram click here.
Other name(s): furanocoumarin 8-methyltransferase; furanocoumarin 8-O-methyl-transferase; xanthotoxol 8-O-methyltransferase; XMT; S-adenosyl-L-methionine:8-hydroxyfuranocoumarin 8-O-methyltransferase
Systematic name: S-adenosyl-L-methionine:8-hydroxyfurocoumarin 8-O-methyltransferase
Comments: Converts xanthotoxol into xanthotoxin, which has therapeutic potential in the treatment of psoriasis as it has photosensitizing and antiproliferative activities [4]. Methylates the 8-hydroxy group of some hydroxy- and methylcoumarins, but has little activity on non-coumarin phenols. (see also EC 2.1.1.69, 5-hydroxyfuranocoumarin 5-O-methyltransferase)
Links to other databases: BRENDA, EXPASY, KEGG, ERGO, CAS registry number: 67339-13-3
References:
1. Thompson, H.J., Sharma, S.K. and Brown, S.A. O-Methyltransferases of furanocoumarin biosynthesis. Arch. Biochem. Biophys. 188 (1978) 272-281. [PMID: 28084]
2. Sharma, S.K., Garrett, J.M. and Brown, S.A. Separation of the S-adenosylmethionine: 5- and 8-hydroxyfuranocoumarin O-methyltransferases of Ruta graveolens L. by general ligand affinity chromatography. Z. Naturforsch. [C] 34C (1979) 387-391. [PMID: 156999]
3. Hauffe, K.D., Hahlbrock, K. and Scheel, D. Elicitor-stimulated furanocoumarin biosynthesis in cultured parsley cells - S-adenosyl-L-methionine-bergaptol and S-adenosyl-L-methionine-xanthotoxol O-methyltransferases. Z. Naturforsch. C: Biosci. 41 (1986) 228-239.
4. Hehmann, M., Lukacin, R., Ekiert, H. and Matern, U. Furanocoumarin biosynthesis in Ammi majus L. Cloning of bergaptol O-methyltransferase. Eur. J. Biochem. 271 (2004) 932-940. [PMID: 15009205]
[EC 2.1.1.92 Deleted entry: bergaptol O-methyltransferase. Now included with EC 2.1.1.69, 5-hydroxyfuranocoumarin 5-O-methyltransferase. The reaction with bergaptol is a specific example of the general reaction associated with EC 2.1.1.69. (EC 2.1.1.92 created 1989, deleted 2006)]
Accepted name: UTP-monosaccharide-1-phosphate uridylyltransferase
Reaction: UTP + a monosaccharide 1-phosphate = diphosphate + UDP-monosaccharide
Glossary: UDP-Xyl = UDP-α-D-xylose
UDP-L-Ara = UDP-β-L-arabinopyranose
Other name(s): UDP-sugar pyrophosphorylase; PsUSP
Comments: Requires Mg2+ or Mn2+ for maximal activity. The reaction can occur in either direction and it has been postulated that MgUTP and Mg-diphosphate are the actual substrates [1,2]. The enzyme catalyses the formation of UDP-Glc, UDP-Gal, UDP-GlcA, UDP-L-Ara and UDP-Xyl, showing broad substrate specificity towards monosaccharide 1-phosphates. Mannose 1-phosphate, L-fucose 1-phosphate and glucose 6-phosphate are not substrates and UTP cannot be replaced by other nucleotide triphosphates [1].
References:
1. Kotake, T., Yamaguchi, D., Ohzono, H., Hojo, S., Kaneko, S., Ishida, H.K. and Tsumuraya, Y. UDP-sugar pyrophosphorylase with broad substrate specificity toward various monosaccharide 1-phosphates from pea sprouts. J. Biol. Chem. 279 (2004) 45728-45736. [PMID: 15326166]
2. Rudick, V.L. and Weisman, R.A. Uridine diphosphate glucose pyrophosphorylase of Acanthamoeba castellanii. Purification, kinetic, and developmental studies. J. Biol. Chem. 249 (1974) 7832-7840. [PMID: 4430676]
Accepted name: sphingomyelin synthase
Reaction: a ceramide + a phosphatidylcholine = a sphingomyelin + a 1,2-diacyl-sn-glycerol
For diagram click here.
Glossary: sphingomyelin = a ceramide-1-phosphocholine
ceramide = an N-acylsphingoid. The fatty acids of naturally occurring ceramides range in chain length from about C16 to about C26 and may contain one or more double bonds and/or hydroxy substituents at C-2
sphingoid = sphinganine, i.e. D-erythro-2-aminooctadecane-1,3-diol, and its homologues and stereoisomers (see also Lip-1.4)
Other name(s): SM synthase; SMS1; SMS2
Systematic name: ceramide:phosphatidylcholine cholinephosphotransferase
Comments: The reaction can occur in both directions [3]. This enzyme occupies a central position in sphingolipid and glycerophospholipid metabolism [4]. Up- and down-regulation of its activity has been linked to mitogenic and pro-apoptotic signalling in a variety of mammalian cell types [4]. Unlike EC 2.7.8.3, ceramide cholinephosphotransferase, CDP-choline cannot replace phosphatidylcholine as the donor of the phosphocholine moiety of sphingomyelin [2].
References:
1. Ullman, M.D. and Radin, N.S. The enzymatic formation of sphingomyelin from ceramide and lecithin in mouse liver. J. Biol. Chem. 249 (1974) 1506-1512. [PMID: 4817756]
2. Voelker, D.R. and Kennedy, E.P. Cellular and enzymic synthesis of sphingomyelin. Biochemistry 21 (1982) 2753-2759. [PMID: 7093220]
3. Huitema, K., van den Dikkenberg, J., Brouwers, J.F. and Holthuis, J.C. Identification of a family of animal sphingomyelin synthases. EMBO J. 23 (2004) 33-44. [PMID: 14685263]
4. Tafesse, F.G., Ternes, P. and Holthuis, J.C. The multigenic sphingomyelin synthase family. J. Biol. Chem. 281 (2006) 29421-29425. [PMID: 16905542]
5. Yamaoka, S., Miyaji, M., Kitano, T., Umehara, H. and Okazaki, T. Expression cloning of a human cDNA restoring sphingomyelin synthesis and cell growth in sphingomyelin synthase-defective lymphoid cells. J. Biol. Chem. 279 (2004) 18688-18693. [PMID: 14976195]
Accepted name: D-Ala-D-Ala dipeptidase
Reaction: D-Ala-D-Ala + H2O = 2 D-Ala
Other name(s): D-alanyl-D-alanine dipeptidase; vanX D-Ala-D-Ala dipeptidase; VanX
Comments: A Zn2+-dependent enzyme [4]. The enzyme protects Enterococcus faecium from the antibiotic vancomycin, which can bind to the -D-Ala-D-Ala sequence at the C-terminus of the peptidoglycan pentapeptide (see diagram). This enzyme reduces the availability of the free dipeptide D-Ala-D-Ala, which is the precursor for this pentapeptide sequence, allowing D-Ala-(R)-lactate (for which vancomycin has much less affinity) to be added to the cell wall instead [2,3]. The enzyme is stereospecific, as L-Ala-L-Ala, D-Ala-L-Ala and L-Ala-D-Ala are not substrates [2]. Belongs in peptidase family M15.
Links to other databases: BRENDA, EXPASY, KEGG, ERGO, CAS registry number:
References:
1. Reynolds, P.E., Depardieu, F., Dutka-Malen, S., Arthur, M. and Courvalin, P. Glycopeptide resistance mediated by enterococcal transposon Tn1546 requires production of VanX for hydrolysis of D-alanyl-D-alanine. Mol. Microbiol. 13 (1994) 1065-1070. [PMID: 7854121]
2. Wu, Z., Wright, G.D. and Walsh, C.T. Overexpression, purification, and characterization of VanX, a D-, D-dipeptidase which is essential for vancomycin resistance in Enterococcus faecium BM4147. Biochemistry 34 (1995) 2455-2463. [PMID: 7873524]
3. McCafferty, D.G., Lessard, I.A. and Walsh, C.T. Mutational analysis of potential zinc-binding residues in the active site of the enterococcal D-Ala-D-Ala dipeptidase VanX. Biochemistry 36 (1997) 10498-10505. [PMID: 9265630]
4. Bussiere, D.E., Pratt, S.D., Katz, L., Severin, J.M., Holzman, T. and Park, C.H. The structure of VanX reveals a novel amino-dipeptidase involved in mediating transposon-based vancomycin resistance. Mol. Cell. 2 (1998) 75-84. [PMID: 9702193]
5. Tan, A.L., Loke, P. and Sim, T.S. Molecular cloning and functional characterisation of VanX, a D-alanyl-D-alanine dipeptidase from Streptomyces coelicolor A3(2). Res. Microbiol. 153 (2002) 27-32. [PMID: 11881895]
6. Matthews, M.L., Periyannan, G., Hajdin, C., Sidgel, T.K., Bennett, B. and Crowder, M.W. Probing the reaction mechanism of the D-ala-D-ala dipeptidase, VanX, by using stopped-flow kinetic and rapid-freeze quench EPR studies on the Co(II)-substituted enzyme. J. Am. Chem. Soc. 128 (2006) 13050-13051. [PMID: 17017774]
Accepted name: enamidase
Reaction: 6-oxo-1,4,5,6-tetrahydronicotinate + 2 H2O = 2-formylglutarate + NH3
For diagram click here.
Systematic name: 6-oxo-1,4,5,6-tetrahydronicotinate amidohydrolase
Comments: Contains iron and Zn2+. Forms part of the nicotinate-fermentation catabolism pathway in Eubacterium barkeri. Other enzymes involved in this pathway are EC 1.17.1.5 (nicotinate dehydrogenase), EC 1.3.7.1 (6-hydroxynicotinate reductase), EC 1.1.1.291 (2-hydroxymethylglutarate dehydrogenase), EC 5.4.99.4 (2-methyleneglutarate mutase), EC 5.3.3.6 (methylitaconate Δ-isomerase), EC 4.2.1.85 (dimethylmaleate hydratase) and EC 4.1.3.32 (2,3-dimethylmalate lyase).
References:
1. Alhapel, A., Darley, D.J., Wagener, N., Eckel, E., Elsner, N. and Pierik, A.J. Molecular and functional analysis of nicotinate catabolism in Eubacterium barkeri. Proc. Natl. Acad. Sci. USA 103 (2006) 12341-12346. [PMID: 16894175]
Accepted name: aldos-2-ulose dehydratase
Reaction: 1,5-anhydro-D-fructose = 2-hydroxy-2-(hydroxymethyl)-2H-pyran-3(6H)-one
+ H2O (overall reaction)
(1a) 1,5-anhydro-D-fructose = 1,5-anhydro-4-deoxy-D-glycero-hex-3-en-2-ulose + H2O
(1b) 1,5-anhydro-4-deoxy-D-glycero-hex-3-en-2-ulose = 2-hydroxy-2-(hydroxymethyl)-2H-pyran-3(6H)-one
For diagram click here.
Glossary: 1,5-anhydro-D-fructose = 1,5-anhydro-D-arabino-hex-2-ulose = (4S,5S,6R)-4,5-dihydroxy-6-(hydroxymethyl)dihydro-2H-pyran-3(4H)-one
ascopyrone M = 1,5-anhydro-4-deoxy-D-glycero-hex-3-en-2-ulose = (6S)-4-hydroxy-6-(hydroxymethyl)-2H-pyran-3(6H)-one
microthecin = 2-hydroxy-2-(hydroxymethyl)-2H-pyran-3(6H)-one
Other name(s): pyranosone dehydratase; AUDH; 1,5-anhydro-D-fructose dehydratase (microthecin-forming)
Systematic name: 1,5-anhydro-D-fructose hydro-lyase (microthecin-forming)
Comments: This enzyme catalyses two of the steps in the anhydrofructose pathway, which leads to the degradation of glycogen and starch via 1,5-anhydro-D-fructose [1,2]. The other enzymes involved in this pathway are EC 4.2.1.111 (1,5-anhydro-D-fructose dehydratase), EC 4.2.2.13 (exo-(1→4)-α-D-glucan lyase) and EC 5.3.3.15 (ascopyrone tautomerase). Aldose-2-uloses such as 2-dehydroglucose can also act as substrates, but more slowly [1,2,4]. This is a bifunctional enzyme that acts as both a lyase and as an isomerase [2]. Differs from EC 4.2.1.111, which can carry out only reaction (1a) and requires a cofactor for activity [5].
References:
1. Yu, S. and Fiskesund, R. The anhydrofructose pathway and its possible role in stress response and signaling. Biochim. Biophys. Acta 1760 (2006) 1314-1322. [PMID: 16822618]
2. Yu, S. Enzymatic description of the anhydrofructose pathway of glycogen degradation. II. Gene identification and characterization of the reactions catalyzed by aldos-2-ulose dehydratase that converts 1,5-anhydro-D-fructose to microthecin with ascopyrone M as the intermediate. Biochim. Biophys. Acta 1723 (2005) 63-73. [PMID: 15716041]
3. Broberg, A., Kenne, L. and Pedersén, M. Presence of microthecin in the red alga Gracilariopsis lemaneiformis and its formation from 1,5-anhydro-D-fructose. Phytochemistry 41 (1996) 151-154.
4. Gabriel, J., Volc, J., Sedmera, P., Daniel, G. and Kubátová, E. Pyranosone dehydratase from the basidiomycete Phanerochaete chrysosporium: improved purification, and identification of 6-deoxy-D-glucosone and D-xylosone reaction products. Arch. Microbiol. 160 (1993) 27-34. [PMID: 8352649]
5. Yu, S., Refdahl, C. and Lundt, I. Enzymatic description of the anhydrofructose pathway of glycogen degradation; I. Identification and purification of anhydrofructose dehydratase, ascopyrone tautomerase and α-1,4-glucan lyase in the fungus Anthracobia melaloma. Biochim. Biophys. Acta 1672 (2004) 120-129. [PMID: 15110094]
Accepted name: 1,5-anhydro-D-fructose dehydratase
Reaction: 1,5-anhydro-D-fructose = 1,5-anhydro-4-deoxy-D-glycero-hex-3-en-2-ulose + H2O
For diagram click here.
Glossary: 1,5-anhydro-D-fructose = 1,5-anhydro-D-arabino-hex-2-ulose = (4S,5S,6R)-4,5-dihydroxy-6-(hydroxymethyl)dihydro-2H-pyran-3(4H)-one
ascopyrone M = 1,5-anhydro-4-deoxy-D-glycero-hex-3-en-2-ulose = 4-hydroxy-6-(hydroxymethyl)-2H-pyran-3(6H)-one
Other name(s): 1,5-anhydro-D-fructose 4-dehydratase; 1,5-anhydro-D-fructose hydrolyase; 1,5-anhydro-D-arabino-hex-2-ulose dehydratase; AFDH; AF dehydratase
Systematic name: 1,5-anhydro-D-fructose hydro-lyase
Comments: This enzyme catalyses one of the steps in the anhydrofructose pathway, which leads to the degradation of glycogen and starch via 1,5-anhydro-D-fructose [1,2]. The other enzymes involved in this pathway are EC 4.2.1.110 (aldos-2-ulose dehydratase), EC 4.2.2.13 [exo-(1→4)-α-D-glucan lyase] and EC 5.3.3.15 (ascopyrone tautomerase). Requires divalent (Ca2+ or Mg2+) or monovalent cations (Na+) for optimal activity. Unlike EC 4.2.1.110, aldos-2-ulose dehydratase, the enzyme is specific for 1,5-anhydro-D-fructose as substrate and shows no activity towards aldose-2-uloses such as 2-dehydroglucose [1,2,3]. In addition, it is inhibited by its end-product ascopyrone M [2] and it cannot convert ascopyrone M into microthecin, as can EC 4.2.1.110.
References:
1. Yu, S., Refdahl, C. and Lundt, I. Enzymatic description of the anhydrofructose pathway of glycogen degradation; I. Identification and purification of anhydrofructose dehydratase, ascopyrone tautomerase and α-1,4-glucan lyase in the fungus Anthracobia melaloma. Biochim. Biophys. Acta 1672 (2004) 120-129. [PMID: 15110094]
2. Yu, S. and Fiskesund, R. The anhydrofructose pathway and its possible role in stress response and signaling. Biochim. Biophys. Acta 1760 (2006) 1314-1322. [PMID: 16822618]
3. Yu, S. Enzymatic description of the anhydrofructose pathway of glycogen degradation. II. Gene identification and characterization of the reactions catalyzed by aldos-2-ulose dehydratase that converts 1,5-anhydro-D-fructose to microthecin with ascopyrone M as the intermediate. Biochim. Biophys. Acta 1723 (2005) 63-73. [PMID: 15716041]
Accepted name: ascopyrone tautomerase
Reaction: 1,5-anhydro-4-deoxy-D-glycero-hex-3-en-2-ulose = 1,5-anhydro-4-deoxy-D-glycero-hex-1-en-3-ulose
For diagram click here.
Glossary: ascopyrone M = 1,5-anhydro-4-deoxy-D-glycero-hex-3-en-2-ulose = 4-hydroxy-6-(hydroxymethyl)-2H-pyran-3(6H)-one
ascopyrone P = 1,5-anhydro-4-deoxy-D-glycero-hex-1-en-3-ulose = 5-hydroxy-2-(hydroxymethyl)-2H-pyran-4(3H)-one
Other name(s): ascopyrone isomerase; ascopyrone intramolecular oxidoreductase; 1,5-anhydro-D-glycero-hex-3-en-2-ulose tautomerase; APM tautomerase; ascopyrone P tautomerase; APTM
Systematic name: 1,5-anhydro-4-deoxy-D-glycero-hex-3-en-2-ulose Δ3-Δ1-isomerase
Comments: This enzyme catalyses one of the steps in the anhydrofructose pathway, which leads to the degradation of glycogen and starch via 1,5-anhydro-D-fructose [1,2]. The other enzymes involved in this pathway are EC 4.2.1.110 (aldos-2-ulose dehydratase), EC 4.2.1.111 (1,5-anhydro-D-fructose dehydratase) and EC 4.2.2.13 [exo-(1→4)-α-D-glucan lyase]. Ascopyrone P is an anti-oxidant [2].
References:
1. Yu, S., Refdahl, C. and Lundt, I. Enzymatic description of the anhydrofructose pathway of glycogen degradation; I. Identification and purification of anhydrofructose dehydratase, ascopyrone tautomerase and α-1,4-glucan lyase in the fungus Anthracobia melaloma. Biochim. Biophys. Acta 1672 (2004) 120-129. [PMID: 15110094]
2. Yu, S. and Fiskesund, R. The anhydrofructose pathway and its possible role in stress response and signaling. Biochim. Biophys. Acta 1760 (2006) 1314-1322. [PMID: 16822618]
Accepted name: D-aspartate ligase
Reaction: ATP + D-aspartate + [β-GlcNAc-(1→4)-Mur2Ac(oyl-L-Ala-γ-D-Glu-L-Lys-D-Ala-D-Ala)]n = [β-GlcNAc-(1→4)-Mur2Ac(oyl-L-Ala-γ-D-Glu-6-N-(β-D-Asp)-L-Lys-D-Ala-D-Ala)]n + ADP + phosphate
For diagram click here.
Other name(s): Aslfm; UDP-MurNAc-pentapeptide:D-aspartate ligase; D-aspartic acid-activating enzyme
Systematic name: D-aspartate:[β-GlcNAc-(1→4)-Mur2Ac(oyl-L-Ala-γ-D-Glu-L-Lys-D-Ala-D-Ala)]n ligase (ADP-forming)
Comments: This enzyme forms part of the peptidoglycan assembly pathway of Gram-positive bacteria grown in medium containing D-Asp. Normally, the side chains the acylate the 6-amino group of the L-lysine residue contain L-Ala-L-Ala but these amino acids are replaced by D-Asp when D-Asp is included in the medium. Hybrid chains containing L-Ala-D-Asp, L-Ala-L-Ala-D-Asp or D-Asp-L-Ala are not formed [4]. The enzyme belongs in the ATP-grasp protein superfamily [3,4]. The enzyme is highly specific for D-aspartate, as L-aspartate, D-glutamate, D-alanine, D-iso-asparagine and D-malic acid are not substrates [4]. In Enterococcus faecium, the substrate D-aspartate is produced by EC 5.1.1.13, aspartate racemase [4]
References:
1. Staudenbauer, W. and Strominger, J.L. Activation of D-aspartic acid for incorporation into peptidoglycan. J. Biol. Chem. 247 (1972) 5095-5102. [PMID: 4262567]
2. Staudenbauer, W., Willoughby, E. and Strominger, J.L. Further studies of the D-aspartic acid-activating enzyme of Streptococcus faecalis and its attachment to the membrane. J. Biol. Chem. 247 (1972) 5289-5296. [PMID: 4626717]
3. Galperin, M.Y. and Koonin, E.V. A diverse superfamily of enzymes with ATP-dependent carboxylate-amine/thiol ligase activity. Protein Sci. 6 (1997) 2639-2643. [PMID: 9416615]
4. Bellais, S., Arthur, M., Dubost, L., Hugonnet, J.E., Gutmann, L., van Heijenoort, J., Legrand, R., Brouard, J.P., Rice, L. and Mainardi, J.L. Aslfm, the D-aspartate ligase responsible for the addition of D-aspartic acid onto the peptidoglycan precursor of Enterococcus faecium. J. Biol. Chem. 281 (2006) 11586-11594. [PMID: 16510449]
Accepted name: 2-oxoglutarate carboxylase
Reaction: ATP + 2-oxoglutarate + HCO3- = ADP + phosphate + oxalosuccinate
For diagram click here.
Glossary: oxalosuccinate = 1-oxopropane-1,2,3-tricarboxylate
Other name(s): oxalosuccinate synthetase; carboxylating factor for ICDH (incorrect); CFI; OGC
Comments: A biotin-containing enzyme that requires Mg2+ for activity. It was originally thought [1] that this enzyme was a promoting factor for the carboxylation of 2-oxoglutarate by EC 1.1.1.41, isocitrate dehydrogenase (NAD+), but this has since been disproved [2]. The product of the reaction is unstable and is quickly converted into isocitrate by the action of EC 1.1.1.41 [2].
References:
1. Aoshima, M., Ishii, M. and Igarashi, Y. A novel biotin protein required for reductive carboxylation of 2-oxoglutarate by isocitrate dehydrogenase in Hydrogenobacter thermophilus TK-6. Mol. Microbiol. 51 (2004) 791-798. [PMID: 14731279]
2. Aoshima, M. and Igarashi, Y. A novel oxalosuccinate-forming enzyme involved in the reductive carboxylation of 2-oxoglutarate in Hydrogenobacter thermophilus TK-6. Mol. Microbiol. 62 (2006) 748-759. [PMID: 17076668]