Enzyme Nomenclature

Continued from EC 5.2

EC 5.3

Intramolecular Oxidoreductases

Sections

EC 5.3.1 Interconverting Aldoses and Ketoses
EC 5.3.2 Interconverting Keto- and Enol-Groups
EC 5.3.3 Transposing C=C Bonds
EC 5.3.4 Transposing S-S Bonds
EC 5.3.99 Other Intramolecular Oxidoreductases


EC 5.3.1 Interconverting Aldoses and Ketoses

Contents

EC 5.3.1.1 triose-phosphate isomerase
EC 5.3.1.2 deleted
EC 5.3.1.3 D-arabinose isomerase
EC 5.3.1.4 L-arabinose isomerase
EC 5.3.1.5 xylose isomerase
EC 5.3.1.6 ribose-5-phosphate isomerase
EC 5.3.1.7 mannose isomerase
EC 5.3.1.8 mannose-6-phosphate isomerase
EC 5.3.1.9 glucose-6-phosphate isomerase
EC 5.3.1.10 now EC 3.5.99.6
EC 5.3.1.11 deleted
EC 5.3.1.12 glucuronate isomerase
EC 5.3.1.13 arabinose-5-phosphate isomerase
EC 5.3.1.14 L-rhamnose isomerase
EC 5.3.1.15 D-lyxose ketol-isomerase
EC 5.3.1.16 1-(5-phosphoribosyl)-5-[(5-phosphoribosylamino)methylideneamino]imidazole-4-carboxamide isomerase
EC 5.3.1.17 5-dehydro-4-deoxy-D-glucuronate isomerase
EC 5.3.1.18 deleted
EC 5.3.1.19 now EC 2.6.1.16
EC 5.3.1.20 ribose isomerase
EC 5.3.1.21 corticosteroid side-chain-isomerase
EC 5.3.1.22 hydroxypyruvate isomerase
EC 5.3.1.23 5-methylthioribose-1-phosphate isomerase
EC 5.3.1.24 phosphoribosylanthranilate isomerase
EC 5.3.1.25 L-fucose isomerase
EC 5.3.1.26 galactose-6-phosphate isomerase
EC 5.3.1.27 6-phospho-3-hexuloisomerase
EC 5.3.1.28 D-sedoheptulose 7-phosphate isomerase
EC 5.3.1.29 ribose 1,5-bisphosphate isomerase
EC 5.3.1.30 5-deoxy-glucuronate isomerase
EC 5.3.1.31 sulfoquinovose isomerase
EC 5.3.1.32 (4S)-4-hydroxy-5-phosphooxypentane-2,3-dione isomerase
EC 5.3.1.33 L-erythrulose 1-phosphate isomerase
EC 5.3.1.34 D-erythrulose 4-phosphate isomerase
EC 5.3.1.35 2-dehydrotetronate isomerase

Entries

EC 5.3.1.1

Accepted name: triose-phosphate isomerase

Reaction: D-glyceraldehyde 3-phosphate = glycerone phosphate

For diagram of reaction click here, alternatives click here or click here.

Other name(s): phosphotriose isomerase; triose phosphoisomerase; triose phosphate mutase; D-glyceraldehyde-3-phosphate ketol-isomerase

Systematic name: D-glyceraldehyde-3-phosphate aldose-ketose-isomerase

Links to other databases: BRENDA, EXPASY, GTD, KEGG, Metacyc, PDB, CAS registry number: 9023-78-3

References:

1. Meyer-Arendt, E., Beisenherz, G. and Bücher, T. Triosephosphate isomerase. Naturwissenschaften 40 (1953) 59 only.

2. Meyerhof, O. and Beck, L.V. Triosephosphate isomerase. J. Biol. Chem. 156 (1944) 109-120.

[EC 5.3.1.1 created 1961]

[EC 5.3.1.2 Deleted entry: erythrose isomerase (EC 5.3.1.2 created 1961, deleted 1976)]

EC 5.3.1.3

Accepted name: D-arabinose isomerase

Reaction: D-arabinose = D-ribulose

Other name(s): D-arabinose(L-fucose) isomerase; L-fucose isomerase; D-arabinose ketol-isomerase; arabinose isomerase (misleading)

Systematic name: D-arabinose aldose-ketose-isomerase

Comments: Requires a divalent metal ion (the enzyme from the bacterium Escherichia coli prefers Mn2+). The enzyme binds the closed form of the sugar and catalyses ring opening to generate a form of open-chain conformation that facilitates the isomerization reaction, which proceeds via an ene-diol mechanism [3]. The enzyme catalyses the aldose-ketose isomerization of several sugars. Most enzymes also catalyse the reaction of EC 5.3.1.25, L-fucose isomerase [3]. The enzyme from the bacterium Falsibacillus pallidus also converts D-altrose to D-psicose [4]. cf. EC 5.3.1.4, L-arabinose isomerase.

Links to other databases: BRENDA, EXPASY, GTD, KEGG, Metacyc, CAS registry number: 9023-81-8

References:

1. Cohen, S.S. Studies on D-ribulose and its enzymatic conversion to D-arabinose. J. Biol. Chem. 201 (1953) 71-84. [PMID: 13044776]

2. Green, M. and Cohen, S.S. Enzymatic conversion of L-fucose to L-fuculose. J. Biol. Chem. 219 (1956) 557-568. [PMID: 13319278]

3. Seemann, J.E. and Schulz, G.E. Structure and mechanism of L-fucose isomerase from Escherichia coli. J. Mol. Biol. 273 (1997) 256-268. [PMID: 9367760]

4. Takeda, K., Yoshida, H., Izumori, K. and Kamitori, S. X-ray structures of Bacillus pallidus D-arabinose isomerase and its complex with L-fucitol. Biochim. Biophys. Acta 1804 (2010) 1359-1368. [PMID: 20123133]

[EC 5.3.1.3 created 1961, modified 2013]

EC 5.3.1.4

Accepted name: L-arabinose isomerase

Reaction: L-arabinose = L-ribulose

Other Name(s): L-arabinose ketol-isomerase

Systematic name: L-arabinose aldose-ketose-isomerase

Comments: Requires a divalent metal ion (the enzyme from the bacterium Escherichia coli prefers Mn2+) [2]. The enzyme binds the closed form of the sugar and catalyses ring opening to generate a form of open-chain conformation that facilitates the isomerization reaction, which proceeds via an ene-diol mechanism [5]. The enzyme can also convert D-galactose to D-tagatose with lower efficiency [4].

Links to other databases: BRENDA, EXPASY, GTD, KEGG, Metacyc, PDB, CAS registry number: 9023-80-7

References:

1. Heath, E.C., Horecker, B.L., Smyrniotis, P.Z. and Takagi, Y. Pentose formation by Lactobacillus plantarum. II. L-Arabinose isomerase. J. Biol. Chem. 231 (1958) 1031-1037.

2. Patrick, J.W. and Lee, N. Purification and properties of an L-arabinose isomerase from Escherichia coli. J. Biol. Chem. 243 (1968) 4312-4318. [PMID: 4878429]

3. Nakamatu, T. and Yamanaka, K. Crystallization and properties of L-arabinose isomerase from Lactobacillus gayonii. Biochim. Biophys. Acta 178 (1969) 156-165. [PMID: 5773448]

4. Cheetham, P.S.J. and Wootton, A.N. Bioconversion of D-galactose into D-tagatose. Enzyme Microb. Technol. 15 (1993) 105-108.

5. Banerjee, S., Anderson, F. and Farber, G.K. The evolution of sugar isomerases. Protein Eng. 8 (1995) 1189-1195. [PMID: 8869631]

6. Manjasetty, B.A. and Chance, M.R. Crystal structure of Escherichia coli L-arabinose isomerase (ECAI), the putative target of biological tagatose production. J. Mol. Biol. 360 (2006) 297-309. [PMID: 16756997]

[EC 5.3.1.4 created 1961]

EC 5.3.1.5

Accepted name: xylose isomerase

Reaction: D-xylose = D-xylulose

Other name(s): D-xylose isomerase; D-xylose ketoisomerase; D-xylose ketol-isomerase

Systematic name: D-xylose aldose-ketose-isomerase

Comments: Contains two divalent metal ions, preferably magnesium, located at different metal-binding sites within the active site. The enzyme catalyses the interconversion of aldose and ketose sugars with broad substrate specificity. The enzyme binds the closed form of its sugar substrate (in the case of glucose, only the α anomer) and catalyses ring opening to generate a form of open-chain conformation that is coordinated to one of the metal sites. Isomerization proceeds via a hydride-shift mechanism.

Links to other databases: BRENDA, EXPASY, GTD, KEGG, Metacyc, PDB, CAS registry number: 9023-82-9

References:

1. Hochster, R.M. and Watson, R.W. Enzymatic isomerization of D-xylose to D-xylulose. Arch. Biochem. Biophys. 48 (1954) 120-129.

2. Slein, M.W. Xylose isomerase from Pasteurella pestis, strain A-1122. J. Am. Chem. Soc. 77 (1955) 1663-1667.

3. Yamanaka, K. Purification, crystallization and properties of the D-xylose isomerase from Lactobacillus brevis. Biochim. Biophys. Acta 151 (1968) 670-680. [PMID: 5646045]

4. Carrell, H.L., Glusker, J.P., Burger, V., Manfre, F., Tritsch, D. and Biellmann, J.F. X-ray analysis of D-xylose isomerase at 1.9 Å: native enzyme in complex with substrate and with a mechanism-designed inactivator. Proc. Natl. Acad. Sci. USA 86 (1989) 4440-4444. [PMID: 2734296]

5. Collyer, C.A. and Blow, D.M. Observations of reaction intermediates and the mechanism of aldose-ketose interconversion by D-xylose isomerase. Proc. Natl. Acad. Sci. USA 87 (1990) 1362-1366. [PMID: 2304904]

6. Whitlow, M., Howard, A.J., Finzel, B.C., Poulos, T.L., Winborne, E. and Gilliland, G.L. A metal-mediated hydride shift mechanism for xylose isomerase based on the 1.6 Å Streptomyces rubiginosus structures with xylitol and D-xylose. Proteins 9 (1991) 153-173. [PMID: 2006134]

7. Allen, K.N., Lavie, A., Glasfeld, A., Tanada, T.N., Gerrity, D.P., Carlson, S.C., Farber, G.K., Petsko, G.A. and Ringe, D. Role of the divalent metal ion in sugar binding, ring opening, and isomerization by D-xylose isomerase: replacement of a catalytic metal by an amino acid. Biochemistry 33 (1994) 1488-1494. [PMID: 7906142]

[EC 5.3.1.5 created 1961 (EC 5.3.1.18 created 1972, part incorporated 1978)]

EC 5.3.1.6

Accepted name: ribose-5-phosphate isomerase

Reaction: D-ribose 5-phosphate = D-ribulose 5-phosphate

For diagram of reaction click here, alternative click here.

Other name(s): phosphopentosisomerase; phosphoriboisomerase; ribose phosphate isomerase; 5-phosphoribose isomerase; D-ribose 5-phosphate isomerase; D-ribose-5-phosphate ketol-isomerase

Systematic name: D-ribose-5-phosphate aldose-ketose-isomerase

Comments: Also acts on D-ribose 5-diphosphate and D-ribose 5-triphosphate.

Links to other databases: BRENDA, EXPASY, GTD, KEGG, Metacyc, PDB, CAS registry number: 9023-83-0

References:

1. Dickens, F. and Williamson, D.H. Pentose phosphate isomerase and epimerase from animal tissues. Biochem. J. 64 (1956) 567-578.

2. Horecker, B.L., Smyrniotis, P.Z. and Seegmiller, J.E. The enzymatic conversion of 6-phosphogluconate to ribulose-5-phosphate and ribose-5-phosphate. J. Biol. Chem. 193 (1951) 383-396.

3. Hurwitz, J., Weissbach, A., Horecker, B.L. and Smyrniotis, P.Z. Spinach phosphoribulokinase. J. Biol. Chem. 218 (1956) 769-783.

[EC 5.3.1.6 created 1961]

EC 5.3.1.7

Accepted name: mannose isomerase

Reaction: D-mannose = D-fructose

Other name(s): D-mannose isomerase; D-mannose ketol-isomerase

Systematic name: D-mannose aldose-ketose-isomerase

Comments: Also acts on D-lyxose and D-rhamnose.

Links to other databases: BRENDA, EXPASY, GTD, KEGG, Metacyc, CAS registry number: 9031-25-8

References:

1. Palleroni, N.J. and Doudoroff, M. Mannose isomerase of Pseudomonas saccharophila. J. Biol. Chem. 218 (1956) 535-548.

[EC 5.3.1.7 created 1961]

EC 5.3.1.8

Accepted name: mannose-6-phosphate isomerase

Reaction: D-mannose 6-phosphate = D-fructose 6-phosphate

For diagram click here.

Other name(s): phosphomannose isomerase; phosphohexomutase; phosphohexoisomerase; mannose phosphate isomerase; phosphomannoisomerase; D-mannose-6-phosphate ketol-isomerase

Systematic name: D-mannose-6-phosphate aldose-ketose-isomerase

Comments: A zinc protein.

Links to other databases: BRENDA, EXPASY, GTD, KEGG, Metacyc, PDB, CAS registry number: 9023-88-5

References:

1. Bruns, F.H., Noltmann, E. and Willemsen, A. Phosphomannose-isomerase. I. Über die Aktivitätsmessung und die Sulfhydryl-sowie die metallabhängigkeit der Enzymirkung in einigen Tierischen Geweben. Biochem. Z. 330 (1958) 411-420.

2. Gracy, R.W. and Noltmann, E.A. Studies on phosphomannose isomerase. II. Characterization as a zinc metalloenzyme. J. Biol. Chem. 243 (1968) 4109-4116. [PMID: 4969968]

3. Slein, M.W. Phosphomannose isomerase. J. Biol. Chem. 186 (1950) 753-761.

[EC 5.3.1.8 created 1961, modified 1976]

EC 5.3.1.9

Accepted name: glucose-6-phosphate isomerase

Reaction: D-glucose 6-phosphate = D-fructose 6-phosphate

For diagram of reaction click here, alternatives click here or click here.

Other name(s): phosphohexose isomerase; phosphohexomutase; oxoisomerase; hexosephosphate isomerase; phosphosaccharomutase; phosphoglucoisomerase; phosphohexoisomerase; phosphoglucose isomerase; glucose phosphate isomerase; hexose phosphate isomerase; D-glucose-6-phosphate ketol-isomerase

Systematic name: D-glucose-6-phosphate aldose-ketose-isomerase

Comments: Also catalyses the anomerization of D-glucose 6-phosphate.

Links to other databases: BRENDA, EXPASY, GTD, KEGG, Metacyc, PDB, CAS registry number: 9001-41-6

References:

1. Baich, A., Wolfe, R.G. and Reithel, F.J. The enzymes of mammary gland. I. Isolation of phosphoglucose isomerase. J. Biol. Chem. 235 (1960) 3130-3133.

2. Nakagawa, Y. and Noltmann, E.A. Isolation of crystalline phosphoglucose isomerase from brewers' yeast. J. Biol. Chem. 240 (1965) 1877-1881.

3. Noltmann, E. and Bruns, F.H. Reindarstellung und Eigenschaften von Phosphoglucose-isomerase aus Hefe. Biochem. Z. 331 (1959) 436-445.

4. Noltmann, E.A. Isolation of crystalline phosphoglucose isomerase from rabbit muscle. J. Biol. Chem. 239 (1964) 1545-1550.

5. Ramasarma, T. and Giri, K.V. Phosphoglucose isomerase of green gram (Phaseolus radiatus). Arch. Biochem. Biophys. 62 (1956) 91-96.

6. Tsuboi, K.K., Estrada, J. and Hudson, P.B. Enzymes of the human erythrocytes. IV. Phosphoglucose isomerase, purification and properties. J. Biol. Chem. 231 (1958) 19-29.

[EC 5.3.1.9 created 1961, modified 1976 (EC 5.3.1.18 created part 1972, incorporated 1978)]

[EC 5.3.1.10 transferred entry: now EC 3.5.99.6 glucosamine-6-phosphate deaminase (EC 5.3.1.10 created 1961, deleted 2000)]

[EC 5.3.1.11 Deleted entry: acetylglucosaminephosphate isomerase (EC 5.3.1.11 created 1961, deleted 1978)]

EC 5.3.1.12

Accepted name: glucuronate isomerase

Reaction: D-glucuronate = D-fructuronate

Other name(s): uronic isomerase; uronate isomerase; D-glucuronate isomerase; uronic acid isomerase; D-glucuronate ketol-isomerase

Systematic name: D-glucuronate aldose-ketose-isomerase

Comments: Also converts D-galacturonate to D-tagaturonate.

Links to other databases: BRENDA, EXPASY, GTD, KEGG, Metacyc, PDB, CAS registry number: 9023-87-4

References:

1. Ashwell, G., Wahba, A.J. and Hickman, J. Uronic acid metabolism in bacteria. I. Purification and properties of uronic acid isomerase in Escherichia coli. J. Biol. Chem. 235 (1960) 1559-1565.

2. Kilgore, W.W. and Starr, M.P. Catabolism of galacturonic and glucuronic acids by Erwinia carotovora. J. Biol. Chem. 234 (1959) 2227-2235.

[EC 5.3.1.12 created 1961]

EC 5.3.1.13

Accepted name: arabinose-5-phosphate isomerase

Reaction: D-arabinose 5-phosphate = D-ribulose 5-phosphate

Other name(s): kdsD (gene name); gutQ (gene name); arabinose phosphate isomerase; phosphoarabinoisomerase; D-arabinose-5-phosphate ketol-isomerase

Systematic name: D-arabinose-5-phosphate aldose-ketose-isomerase

Comments: The enzyme is involved in the pathway for synthesis of 3-deoxy-D-manno-octulosonate (Kdo), a component of bacterial lipopolysaccharides and plant call walls.

Links to other databases: BRENDA, EXPASY, GTD, KEGG, Metacyc, PDB, CAS registry number: 9023-86-3

References:

1. Volk, W.A. Purification and properties of phosphoarabinoisomerase from Propionibacterium pentosaceum. J. Biol. Chem. 235 (1960) 1550-1553.

2. Lim, R. and Cohen, S.S. D-phosphoarabinoisomerase and D-ribulokinase in Escherichia coli. J. Biol. Chem. 241 (1966) 4304-4315. [PMID: 5332197]

3. Meredith, T.C. and Woodard, R.W. Identification of GutQ from Escherichia coli as a D-arabinose 5-phosphate isomerase. J. Bacteriol. 187 (2005) 6936-6942. [PMID: 16199563]

4. Gourlay, L.J., Sommaruga, S., Nardini, M., Sperandeo, P., Deho, G., Polissi, A. and Bolognesi, M. Probing the active site of the sugar isomerase domain from E. coli arabinose-5-phosphate isomerase via X-ray crystallography. Protein Sci. 19 (2010) 2430-2439. [PMID: 20954237]

5. Chiu, H.J., Grant, J.C., Farr, C.L., Jaroszewski, L., Knuth, M.W., Miller, M.D., Elsliger, M.A., Deacon, A.M., Godzik, A., Lesley, S.A. and Wilson, I.A. Structural analysis of arabinose-5-phosphate isomerase from Bacteroides fragilis and functional implications. Acta Crystallogr. D Biol. Crystallogr. 70 (2014) 2640-2651. [PMID: 25286848]

[EC 5.3.1.13 created 1965]

EC 5.3.1.14

Accepted name: L-rhamnose isomerase

Reaction: L-rhamnose = L-rhamnulose

For diagram of reaction click here.

Other name(s): rhamnose isomerase; L-rhamnose ketol-isomerase

Systematic name: L-rhamnose aldose-ketose-isomerase

Comments: Contains two divalent metal ions located at different metal-binding sites within the active site. The enzyme binds the closed ring form of the substrate and catalyses ring opening to generate a form of open-chain conformation that is coordinated to one of the metal sites. Isomerization proceeds via a hydride-shift mechanism. While the enzyme from the bacterium Escherichia coli is specific for L-rhamnose, the enzyme from the bacterium Pseudomonas stutzeri has broad substrate specificity and catalyses the interconversion of L-mannose and L-fructose, L-lyxose and L-xylulose, D-ribose and D-ribulose, and D-allose and D-psicose [2].

Links to other databases: BRENDA, EXPASY, GTD, KEGG, Metacyc, PDB, CAS registry number: 9023-84-1

References:

1. Domagk, G.F. and Zech, R. Über den Abbau der Desoxyzucker durch Bakterienenzyme. I. L-Rhamnose-Isomerase aus Lactobacillus plantarum. Biochem. Z. 339 (1963) 145-153.

2. Leang, K., Takada, G., Ishimura, A., Okita, M. and Izumori, K. Cloning, nucleotide sequence, and overexpression of the L-rhamnose isomerase gene from Pseudomonas stutzeri in Escherichia coli. Appl. Environ. Microbiol. 70 (2004) 3298-3304. [PMID: 15184124]

3. Korndorfer, I.P., Fessner, W.D. and Matthews, B.W. The structure of rhamnose isomerase from Escherichia coli and its relation with xylose isomerase illustrates a change between inter and intra-subunit complementation during evolution. J. Mol. Biol. 300 (2000) 917-933. [PMID: 10891278]

4. Yoshida, H., Yamada, M., Ohyama, Y., Takada, G., Izumori, K. and Kamitori, S. The structures of L-rhamnose isomerase from Pseudomonas stutzeri in complexes with L-rhamnose and D-allose provide insights into broad substrate specificity. J. Mol. Biol. 365 (2007) 1505-1516. [PMID: 17141803]

[EC 5.3.1.14 created 1965]

EC 5.3.1.15

Accepted name: D-lyxose ketol-isomerase

Reaction: D-lyxose = D-xylulose

Other name(s): D-lyxose isomerase; D-lyxose ketol-isomerase

Systematic name: D-lyxose aldose-ketose-isomerase

Links to other databases: BRENDA, EXPASY, GTD, KEGG, Metacyc, CAS registry number: 37318-42-6

References:

1. Anderson, R.L. and Allison, D.P. Purification and characterization of D-lyxose isomerase. J. Biol. Chem. 240 (1965) 2367-2372.

[EC 5.3.1.15 created 1972]

EC 5.3.1.16

Accepted name: 1-(5-phosphoribosyl)-5-[(5-phosphoribosylamino)methylideneamino]imidazole-4-carboxamide isomerase

Reaction: 1-(5-phospho-β-D-ribosyl)-5-[(5-phospho-β-D-ribosylamino)methylideneamino]imidazole-4-carboxamide = 5-[(5-phospho-1-deoxy-β-D-ribulos-1-ylamino)methylideneamino]-1-(5-phospho-β-D-ribosyl)imidazole-4-carboxamide

For diagram click here.

Other name(s): N-(5'-phospho-D-ribosylformimino)-5-amino-1-(5"-phosphoribosyl)-4-imidazolecarboxamide isomerase; phosphoribosylformiminoaminophosphoribosylimidazolecarboxamide isomerase; N-(phosphoribosylformimino) aminophosphoribosylimidazolecarboxamide isomerase; 1-(5-phosphoribosyl)-5-[(5-phosphoribosylamino)methylideneamino)imidazole-4-carboxamide ketol-isomerase; 1-(5-phosphoribosyl)-5-[(5-phosphoribosylamino)methylideneamino]imidazole-4-carboxamide aldose-ketose-isomerase

Systematic name: 1-(5-phospho-β-D-ribosyl)-5-[(5-phospho-β-D-ribosylamino)methylideneamino]imidazole-4-carboxamide aldose-ketose-isomerase

Comments: Involved in histidine biosynthesis

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 37318-43-7

References:

1. Margolies, M.N. and Goldberger, R.F. Isolation of the fourth (isomerase) of histidine biosynthesis from Salmonella typhimurium. J. Biol. Chem. 241 (1966) 3262-3269. [PMID: 5330429]

[EC 5.3.1.16 created 1972, modified 2000]

EC 5.3.1.17

Accepted name: 5-dehydro-4-deoxy-D-glucuronate isomerase

Reaction: 5-dehydro-4-deoxy-D-glucuronate = 3-deoxy-D-glycero-2,5-hexodiulosonate

Glossary: 5-dehydro-4-deoxy-D-glucuronate = (4S,5R)-4,5-dihydroxy-2,6-dioxohexanoate
3-deoxy-D-glycero-2,5-hexodiulosonate = (4S)-4,6-dihydroxy-2,5-dioxohexanoate

Other name(s): 4-deoxy-L-threo-5-hexulose uronate isomerase; 4-deoxy-L-threo-5-hexosulose-uronate ketol-isomerase; kduI (gene name)

Systematic name: 5-dehydro-4-deoxy-D-glucuronate aldose-ketose-isomerase

Comments: The enzyme is involved in the degradation of polygalacturonate, a later stage in the degradation of pectin by many microorganisms.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 37318-44-8

References:

1. Preiss, J. 4-Deoxy-L-threo-5-hexosulose uronic acid isomerase. Methods Enzymol. 9 (1966) 602-604.

2. Condemine, G. and Robert-Baudouy, J. Analysis of an Erwinia chrysanthemi gene cluster involved in pectin degradation. Mol. Microbiol. 5 (1991) 2191-2202. [PMID: 1766386]

3. Dunten, P., Jaffe, H. and Aksamit, R.R. Crystallization of 5-keto-4-deoxyuronate isomerase from Escherichia coli. Acta Crystallogr. D Biol. Crystallogr. 54 (1998) 678-680. [PMID: 9761873]

4. Crowther, R.L. and Georgiadis, M.M. The crystal structure of 5-keto-4-deoxyuronate isomerase from Escherichia coli. Proteins 61 (2005) 680-684. [PMID: 16152643]

[EC 5.3.1.17 created 1972, modified 2012]

[EC 5.3.1.18 Deleted entry: glucose isomerase. Reaction is due to EC 5.3.1.9 glucose-6-phosphate isomerase, in the presence of arsenate, or EC 5.3.1.5 xylose isomerase (EC 5.3.1.18 created 1972, deleted 1978)]

[EC 5.3.1.19 Transferred entry: now EC 2.6.1.16 glutamine-fructose-6-phosphate aminotransferase (isomerizing) (EC 5.3.1.19 created 1972, deleted 1984)]

EC 5.3.1.20

Accepted name: ribose isomerase

Reaction: D-ribose = D-ribulose

Other name(s): D-ribose isomerase; D-ribose ketol-isomerase

Systematic name: D-ribose aldose-ketose-isomerase

Comments: Also acts on L-lyxose and L-rhamnose.

Links to other databases: BRENDA, EXPASY, GTD, KEGG, Metacyc, CAS registry number: 57534-76-6

References:

1. Izumori, K., Rees, A.W. and Elbein, A.D. Purification, crystallization, and properties of D-ribose isomerase from Mycobacterium smegmatis. J. Biol. Chem. 250 (1975) 8085-8087. [PMID: 240851]

[EC 5.3.1.20 created 1978]

EC 5.3.1.21

Accepted name: corticosteroid side-chain-isomerase

Reaction: 11-deoxycorticosterone = 20-hydroxy-3-oxopregn-4-en-21-al

Other Name(s): 11-deoxycorticosterone ketol-isomerase

Systematic name: 11-deoxycorticosterone aldose-ketose-isomerase

Comments: An epimerization at C-20 and C-21 is probably catalysed by the same enzyme.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number: 75139-73-0

References:

1. Martin, K.O., Oh, S.-W., Lee, H.J. and Monder, C. Studies on 21-3H-labeled corticosteroids: evidence for isomerization of the ketol side chain of 11-deoxycorticosterone by a hamster liver enzyme. Biochemistry 16 (1977) 3803-3809. [PMID: 901753]

2. Monder, C., Martin, K.O. and Bogumil, J. Presence of epimerase activity in hamster liver corticosteroid side chain isomerase. J. Biol. Chem. 255 (1980) 7192-7198. [PMID: 7391077]

[EC 5.3.1.21 created 1983]

EC 5.3.1.22

Accepted name: hydroxypyruvate isomerase

Reaction: hydroxypyruvate = 2-hydroxy-3-oxopropanoate

Glossary: 2-hydroxy-3-oxopropanoate = tartronate semialdehyde

Other Name(s): hydroxypyruvate ketol-isomerase

Systematic name: hydroxypyruvate aldose-ketose-isomerase

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 74812-48-9

References:

1. De Windt, F.E. and van der Drift, D. Purification and some properties of hydroxypyruvate isomerase of Bacillus fastidiosus. Biochim. Biophys. Acta 613 (1980) 556-562. [PMID: 7448201]

[EC 5.3.1.22 created 1983]

EC 5.3.1.23

Accepted name: S-methyl-5-thioribose-1-phosphate isomerase

Reaction: S-methyl-5-thio-α-D-ribose 1-phosphate = S-methyl-5-thio-D-ribulose 1-phosphate

For diagram click here.

Other name(s): methylthioribose 1-phosphate isomerase; 1-PMTR isomerase; 5-methylthio-5-deoxy-D-ribose-1-phosphate ketol-isomerase; S-methyl-5-thio-5-deoxy-D-ribose-1-phosphate ketol-isomerase; S-methyl-5-thio-5-deoxy-D-ribose-1-phosphate aldose-ketose-isomerase; 1-phospho-5′-S-methylthioribose isomerase; S-methyl-5-thio-D-ribose-1-phosphate aldose-ketose-isomerase

Systematic name: S-methyl-5-thio-α-D-ribose-1-phosphate aldose-ketose-isomerase

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 91608-95-6

References:

1. Ghoda, L.Y., Savarese, T.M., Dexter, D.L., Parks, R.E., Jr., Trackman, P.C. and Abeles, R.H. Characterization of a defect in the pathway for converting 5'-deoxy-5'-methylthioadenosine to methionine in a subline of a cultured heterogeneous human colon carcinoma. J. Biol. Chem. 259 (1984) 6715-6719. [PMID: 6725268]

2. Trackman, P.C. and Abeles, R.H. Methionine synthesis from 5'-S-methylthioadenosine - resolution of enzyme-activities and identification of 1-phospho-5-S-methylthioribulose. J. Biol. Chem. 258 (1983) 6717-6720. [PMID: 6853500]

3. Furfine, E.S. and Abeles, R.H. Intermediates in the conversion of 5'-S-methylthioadenosine to methionine in Klebsiella pneumoniae. J. Biol. Chem. 263 (1988) 9598-9606. [PMID: 2838472]

[EC 5.3.1.23 created 1989]

EC 5.3.1.24

Accepted name: phosphoribosylanthranilate isomerase

Reaction: N-(5-phospho-β-D-ribosyl)anthranilate = 1-(2-carboxyphenylamino)-1-deoxy-D-ribulose 5-phosphate

For diagram click here.

Other name(s): PRA isomerase; PRAI; IGPS:PRAI (indole-3-glycerol-phosphate synthetase/N-5'-phosphoribosylanthranilate isomerase complex); N-(5-phospho-β-D-ribosyl)anthranilate ketol-isomerase

Systematic name: N-(5-phospho-β-D-ribosyl)anthranilate aldose-ketose-isomerase

Comments: In some organisms, this enzyme is part of a multifunctional protein, together with one or more other components of the system for the biosynthesis of tryptophan [EC 2.4.2.18 (anthranilate phosphoribosyltransferase), EC 4.1.1.48 (indole-3-glycerol-phosphate synthase), EC 4.1.3.27 (anthranilate synthase) and EC 4.2.1.20 (tryptophan synthase)].

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 37259-82-8

References:

1. Braus, G.H., Luger, K., Paravicini, G., Schmidheini, T., Kirschner, K. and Hütter, R. The role of the TRP1 gene in yeast tryptophan biosynthesis. J. Biol. Chem. 263 (1988) 7868-7875. [PMID: 3286643]

2. Creighton, T.E. and Yanofsky, C. Chorismate to tryptophan (Escherichia coli) - anthranilate synthetase, PR transferase, PRA isomerase, InGP synthetase, tryptophan synthetase. Methods Enzymol. 17A (1970) 365-380.

3. Hütter, R., Niederberger, P. and DeMoss, J.A. Tryptophan biosynthetic genes in eukaryotic microorganisms. Annu. Rev. Microbiol. 40 (1986) 55-77.

[EC 5.3.1.24 created 1990]

EC 5.3.1.25

Accepted name: L-fucose isomerase

Reaction: L-fucose = L-fuculose

Other Name(s): L-fucose ketol-isomerase

Systematic name: L-fucose aldose-ketose-isomerase

Comments: Requires a divalent metal ion (the enzyme from the bacterium Escherichia coli prefers Mn2+). The enzyme binds the closed form of the sugar and catalyses ring opening to generate a form of open-chain conformation that facilitates the isomerization reaction, which proceeds via an ene-diol mechanism [3]. The enzyme from Escherichia coli can also convert D-arabinose to D-ribulose [1]. The enzyme from the thermophilic bacterium Caldicellulosiruptor saccharolyticus also converts D-altrose to D-psicose and L-galactose to L-tagatose [4].

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 60063-83-4

References:

1. Green, M. and Cohen, S.S. Enzymatic conversion of L-fucose to L-fuculose. J. Biol. Chem. 219 (1956) 557-568. [PMID: 13319278]

2. Lu, Z., Lin, E.C.C. The nucleotide sequence of Escherichia coli genes for L-fucose dissimilation. Nucleic Acids Res. 17 (1989) 4883-4884. [PMID: 2664711]

3. Seemann, J.E. and Schulz, G.E. Structure and mechanism of L-fucose isomerase from Escherichia coli. J. Mol. Biol. 273 (1997) 256-268. [PMID: 9367760]

4. Ju, Y.H. and Oh, D.K. Characterization of a recombinant L-fucose isomerase from Caldicellulosiruptor saccharolyticus that isomerizes L-fucose, D-arabinose, D-altrose, and L-galactose. Biotechnol. Lett. 32 (2010) 299-304. [PMID: 19856146]

[EC 5.3.1.25 created 1999]

EC 5.3.1.26

Accepted name: galactose-6-phosphate isomerase

Reaction: D-galactose 6-phosphate = D-tagatose 6-phosphate

Other Name(s): D-galactose-6-phosphate ketol-isomerase

Systematic name: D-galactose-6-phosphate aldose-ketose-isomerase

Comments: involved in the tagatose 6-phosphate pathway of lactose catabolism in bacteria.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number: 39433-98-2

References:

1. De Vos, W.M., Boerrigter, I., Van Rooijen, R.J., Reiche, B., Hengstenberg, W. Characterization of the lactose-specific enzymes of the phosphotransferase system in Lactococcus lactis. J. Biol. Chem. 265 (1990) 22554-22560. [PMID: 2125052]

2. Van Rooijen, R.J., Van Schalkwijk, S., De Vos, W.M. Molecular cloning, characterization, and nucleotide sequence of the tagatose 6-phosphate pathway gene cluster of the lactose operon of Lactococcus lactis. J. Biol. Chem. 266 (1991) 7176-7181. [PMID: 1901863]

[EC 5.3.1.26 created 1999]

EC 5.3.1.27

Accepted name: 6-phospho-3-hexuloisomerase

Reaction: D-arabino-hex-3-ulose 6-phosphate = D-fructose 6-phosphate

For diagram of reaction, click here

Other name(s): 3-hexulose-6-phosphate isomerase; phospho-3-hexuloisomerase; PHI; 6-phospho-3-hexulose isomerase; YckF

Systematic name: D-arabino-3-hexulose-6-phosphate isomerase

Comments: This enzyme, along with EC 4.1.2.43, 3-hexulose-6-phosphate synthase, plays a key role in the ribulose-monophosphate cycle of formaldehyde fixation, which is present in many microorganisms that are capable of utilizing C1-compounds [1]. The hyperthermophilic and anaerobic archaeon Pyrococcus horikoshii OT3 constitutively produces a bifunctional enzyme that sequentially catalyses the reactions of EC 4.1.2.43 (3-hexulose-6-phosphate synthase) and this enzyme [4].

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number:

References:

1. Ferenci, T., Strøm, T. and Quayle, J.R. Purification and properties of 3-hexulose phosphate synthase and phospho-3-hexuloisomerase from Methylococcus capsulatus. Biochem. J. 144 (1974) 477-486. [PMID: 4219834]

2. Yurimoto, H., Kato, N. and Sakai, Y. Assimilation, dissimilation, and detoxification of formaldehyde, a central metabolic intermediate of methylotrophic metabolism. Chem. Rec. 5 (2005) 367-375. [PMID: 16278835]

3. Kato, N., Yurimoto, H. and Thauer, R.K. The physiological role of the ribulose monophosphate pathway in bacteria and archaea. Biosci. Biotechnol. Biochem. 70 (2006) 10-21. [PMID: 16428816]

4. Orita, I., Yurimoto, H., Hirai, R., Kawarabayasi, Y., Sakai, Y. and Kato, N. The archaeon Pyrococcus horikoshii possesses a bifunctional enzyme for formaldehyde fixation via the ribulose monophosphate pathway. J. Bacteriol. 187 (2005) 3636-3642. [PMID: 15901685]

5. Martinez-Cruz, L.A., Dreyer, M.K., Boisvert, D.C., Yokota, H., Martinez-Chantar, M.L., Kim, R. and Kim, S.H. Crystal structure of MJ1247 protein from M. jannaschii at 2.0 Å resolution infers a molecular function of 3-hexulose-6-phosphate isomerase. Structure 10 (2002) 195-204. [PMID: 11839305]

6. Taylor, E.J., Charnock, S.J., Colby, J., Davies, G.J. and Black, G.W. Cloning, purification and characterization of the 6-phospho-3-hexulose isomerase YckF from Bacillus subtilis. Acta Crystallogr. D Biol. Crystallogr. 57 (2001) 1138-1140. [PMID: 11468398]

[EC 5.3.1.27 created 2008]

EC 5.3.1.28

Accepted name: D-sedoheptulose 7-phosphate isomerase

Reaction: D-sedoheptulose 7-phosphate = D-glycero-D-manno-heptose 7-phosphate

Other name(s): sedoheptulose-7-phosphate isomerase; phosphoheptose isomerase; gmhA (gene name); lpcA (gene name)

Systematic name: D-glycero-D-manno-heptose 7-phosphate aldose-ketose-isomerase

Comments: In Gram-negative bacteria the enzyme is involved in biosynthesis of ADP-L-glycero-β-D-manno-heptose, which is utilized for assembly of the lipopolysaccharide inner core. In Gram-positive bacteria the enzyme is involved in biosynthesis of GDP-D-glycero-α-D-manno-heptose, which is required for assembly of S-layer glycoprotein.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number:

References:

1. Kneidinger, B., Marolda, C., Graninger, M., Zamyatina, A., McArthur, F., Kosma, P., Valvano, M.A. and Messner, P. Biosynthesis pathway of ADP-L-glycero-β-D-manno-heptose in Escherichia coli. J. Bacteriol. 184 (2002) 363-369. [PMID: 11751812]

2. Kneidinger, B., Graninger, M., Puchberger, M., Kosma, P. and Messner, P. Biosynthesis of nucleotide-activated D-glycero-D-manno-heptose. J. Biol. Chem. 276 (2001) 20935-20944. [PMID: 11279237]

3. Valvano, M.A., Messner, P. and Kosma, P. Novel pathways for biosynthesis of nucleotide-activated glycero-manno-heptose precursors of bacterial glycoproteins and cell surface polysaccharides. Microbiology 148 (2002) 1979-1989. [PMID: 12101286]

4. Kim, M.S. and Shin, D.H. A preliminary X-ray study of sedoheptulose-7-phosphate isomerase from Burkholderia pseudomallei. Acta Crystallogr. Sect. F Struct. Biol. Cryst. Commun. 65 (2009) 1110-1112. [PMID: 19923728]

5. Taylor, P.L., Blakely, K.M., de Leon, G.P., Walker, J.R., McArthur, F., Evdokimova, E., Zhang, K., Valvano, M.A., Wright, G.D. and Junop, M.S. Structure and function of sedoheptulose-7-phosphate isomerase, a critical enzyme for lipopolysaccharide biosynthesis and a target for antibiotic adjuvants. J. Biol. Chem. 283 (2008) 2835-2845. [PMID: 18056714]

[EC 5.3.1.28 created 2010]

EC 5.3.1.29

Accepted name: ribose 1,5-bisphosphate isomerase

Reaction: α-D-ribose 1,5-bisphosphate = D-ribulose 1,5-bisphosphate

For diagram of reaction click here.

Other name(s): R15P isomerase; ribulose 1,5-bisphosphate synthase; RuBP synthase

Systematic name: α-D-ribose 1,5-bisphosphate aldose-ketose-isomerase

Comments: This archaeal enzyme is involved in AMP metabolism and CO2 fixation through type III RubisCO enzymes. The enzyme is activated by cAMP [2].

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:

References:

1. Sato, T., Atomi, H. and Imanaka, T. Archaeal type III RuBisCOs function in a pathway for AMP metabolism. Science 315 (2007) 1003-1006. [PMID: 17303759]

2. Aono, R., Sato, T., Yano, A., Yoshida, S., Nishitani, Y., Miki, K., Imanaka, T. and Atomi, H. Enzymatic characterization of AMP phosphorylase and ribose-1,5-bisphosphate isomerase functioning in an archaeal AMP metabolic pathway. J. Bacteriol. 194 (2012) 6847-6855. [PMID: 23065974]

3. Nakamura, A., Fujihashi, M., Aono, R., Sato, T., Nishiba, Y., Yoshida, S., Yano, A., Atomi, H., Imanaka, T. and Miki, K. Dynamic, ligand-dependent conformational change triggers reaction of ribose-1,5-bisphosphate isomerase from Thermococcus kodakarensis KOD1. J. Biol. Chem. 287 (2012) 20784-20796. [PMID: 22511789]

[EC 5.3.1.29 created 2013]

EC 5.3.1.30

Accepted name: 5-deoxy-glucuronate isomerase

Reaction: 5-deoxy-D-glucuronate = 5-dehydro-2-deoxy-D-gluconate

For diagram of reaction click here.

Glossary: 5-dehydro-2-deoxy-D-gluconate = 2-deoxy-D-threo-hex-5-ulosonic acid
5-deoxy-D-glucuronate = 5-deoxy-D-xylo-hexuronic acid

Other name(s): 5DG isomerase; IolB

Systematic name: 5-deoxy-D-glucuronate aldose-ketose-isomerase

Comments: The enzyme, found in the bacterium Bacillus subtilis, is part of a myo-inositol degradation pathway leading to acetyl-CoA.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:

References:

1. Yoshida, K., Yamaguchi, M., Morinaga, T., Kinehara, M., Ikeuchi, M., Ashida, H. and Fujita, Y. myo-Inositol catabolism in Bacillus subtilis. J. Biol. Chem. 283 (2008) 10415-10424. [PMID: 18310071]

[EC 5.3.1.30 created 2014]

EC 5.3.1.31

Accepted name: sulfoquinovose isomerase

Reaction: sulfoquinovose = 6-deoxy-6-sulfo-D-fructose

For diagram of reaction click here.

Glossary: sulfoquinovose = 6-deoxy-6-sulfo-D-glucopyranose

Other name(s): yihS (gene name)

Systematic name: 6-deoxy-6-sulfo-D-glucopyranose aldose-ketose-isomerase

Comments: The enzyme, characterized from the bacterium Escherichia coli, is involved in the degradation pathway of sulfoquinovose, the polar headgroup of sulfolipids found in the photosynthetic membranes of all higher plants, mosses, ferns, algae, and most photosynthetic bacteria, as well as the surface layer of some archaea.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:

References:

1. Denger, K., Weiss, M., Felux, A.K., Schneider, A., Mayer, C., Spiteller, D., Huhn, T., Cook, A.M. and Schleheck, D. Sulphoglycolysis in Escherichia coli K-12 closes a gap in the biogeochemical sulphur cycle. Nature 507 (2014) 114-117. [PMID: 24463506]

[EC 5.3.1.31 created 2014]

EC 5.3.1.32

Accepted name: (4S)-4-hydroxy-5-phosphooxypentane-2,3-dione isomerase

Reaction: (4S)-4-hydroxy-5-phosphooxypentane-2,3-dione = 3-hydroxy-5-phosphooxypentane-2,4-dione

Glossary: (4S)-4,5-dihydroxypentane-2,3-dione = autoinducer 2 = AI-2

Other name(s): lsrG (gene name); phospho-AI-2 isomerase; (4S)-4-hydroxy-5-phosphonooxypentane-2,3-dione isomerase; (4S)-4-hydroxy-5-phosphonooxypentane-2,3-dione aldose-ketose-isomerase

Systematic name: (4S)-4-hydroxy-5-phosphooxypentane-2,3-dione aldose-ketose-isomerase

Comments: The enzyme participates in a degradation pathway of the bacterial quorum-sensing autoinducer molecule AI-2.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:

References:

1. Xavier, K.B., Miller, S.T., Lu, W., Kim, J.H., Rabinowitz, J., Pelczer, I., Semmelhack, M.F. and Bassler, B.L. Phosphorylation and processing of the quorum-sensing molecule autoinducer-2 in enteric bacteria. ACS Chem. Biol. 2 (2007) 128-136. [PMID: 17274596]

2. Marques, J.C., Lamosa, P., Russell, C., Ventura, R., Maycock, C., Semmelhack, M.F., Miller, S.T. and Xavier, K.B. Processing the interspecies quorum-sensing signal autoinducer-2 (AI-2): characterization of phospho-(S)-4,5-dihydroxy-2,3-pentanedione isomerization by LsrG protein. J. Biol. Chem. 286 (2011) 18331-18343. [PMID: 21454635]

[EC 5.3.1.32 created 2015]

EC 5.3.1.33

Accepted name: L-erythrulose 1-phosphate isomerase

Reaction: L-erythrulose 1-phosphate = D-erythrulose 4-phosphate

Other name(s): eryH (gene name)

Systematic name: L-erythrulose-1-phosphate isomerase

Comments: The enzyme, characterized from the pathogenic bacterium Brucella abortus, which causes brucellosis in livestock, participates in erythritol catabolism.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:

References:

1. Barbier, T., Collard, F., Zuniga-Ripa, A., Moriyon, I., Godard, T., Becker, J., Wittmann, C., Van Schaftingen, E. and Letesson, J.J. Erythritol feeds the pentose phosphate pathway via three new isomerases leading to D-erythrose-4-phosphate in Brucella. Proc. Natl. Acad. Sci. USA 111 (2014) 17815-17820. [PMID: 25453104]

[EC 5.3.1.33 created 2016]

EC 5.3.1.34

Accepted name: D-erythrulose 4-phosphate isomerase

Reaction: D-erythrulose 4-phosphate = D-erythrose 4-phosphate

Other name(s): eryI (gene name)

Systematic name: D-erythrulose-4-phosphate ketose-aldose isomerase

Comments: The enzyme, characterized from the pathogenic bacterium Brucella abortus, which causes brucellosis in livestock, participates in erythritol catabolism.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:

References:

1. Barbier, T., Collard, F., Zuniga-Ripa, A., Moriyon, I., Godard, T., Becker, J., Wittmann, C., Van Schaftingen, E. and Letesson, J.J. Erythritol feeds the pentose phosphate pathway via three new isomerases leading to D-erythrose-4-phosphate in Brucella. Proc. Natl. Acad. Sci. USA 111 (2014) 17815-17820. [PMID: 25453104]

[EC 5.3.1.34 created 2016]

EC 5.3.1.35

Accepted name: 2-dehydrotetronate isomerase

Reaction: (1) 2-dehydro-L-erythronate = 3-dehydro-L-erythronate
(2) 2-dehydro-D-erythronate = 3-dehydro-D-erythronate

For diagram of reaction click here.

Glossary: L-erythronate = (2S,3S)-2,3,4-trihydroxybutanoate
D-erythronate = (2R,3R)-2,3,4-trihydroxybutanoate

Other name(s): otnI (gene name)

Systematic name: 2-dehydrotetronate isomerase

Comments: The enzyme, characterized from bacteria, is involved in D-erythronate and L-threonate catabolism.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:

References:

1. Zhang, X., Carter, M.S., Vetting, M.W., San Francisco, B., Zhao, S., Al-Obaidi, N.F., Solbiati, J.O., Thiaville, J.J., de Crecy-Lagard, V., Jacobson, M.P., Almo, S.C. and Gerlt, J.A. Assignment of function to a domain of unknown function: DUF1537 is a new kinase family in catabolic pathways for acid sugars. Proc. Natl Acad. Sci. USA 113 (2016) E4161-E4169. [PMID: 27402745]

[EC 5.3.1.35 created 2017]


EC 5.3.2 Interconverting Keto- and Enol-Groups

Contents

EC 5.3.2.1 phenylpyruvate tautomerase
EC 5.3.2.2 oxaloacetate tautomerase
EC 5.3.2.3 TDP-4-oxo-6-deoxy-α-D-glucose-3,4-oxoisomerase (dTDP-3-dehydro-6-deoxy-α-D-galactopyranose-forming)
EC 5.3.2.4 TDP-4-oxo-6-deoxy-α-D-glucose-3,4-oxoisomerase (dTDP-3-dehydro-6-deoxy-α-D-glucopyranose-forming)
EC 5.3.2.5 2,3-diketo-5-methylthiopentyl-1-phosphate enolase
EC 5.3.2.6 2-hydroxymuconate tautomerase
EC 5.3.2.7 ascopyrone tautomerase
EC 5.3.2.8 4-oxalomesaconate tautomerase


Entries

EC 5.3.2.1

Accepted name: phenylpyruvate tautomerase

Reaction: keto-phenylpyruvate = enol-phenylpyruvate

Other name(s): phenylpyruvic keto-enol isomerase

Systematic name: phenylpyruvate keto—enol-isomerase

Comments: Also acts on other arylpyruvates.

Links to other databases: BRENDA, EXPASY, GTD, KEGG, Metacyc, PDB, CAS registry number: 9023-54-5

References:

1. Blasi, F., Fragonmele, F. and Covelli, I. Thyroidal phenylpyruvate tautomerase. Isolation and characterization. J. Biol. Chem. 244 (1969) 4864-4870. [PMID: 5824560]

2. Knox, W.E. p-Hydroxyphenylpyruvate enol-keto tautomerase. Methods Enzymol. 2 (1955) 289-295.

3. Knox, W.E. and Pitt, B.M. Enzymic catalysis of the keto-enol tautomerization of phenylpyruvic acids. J. Biol. Chem. 225 (1957) 675-688.

[EC 5.3.2.1 created 1961]

EC 5.3.2.2

Accepted name: oxaloacetate tautomerase

Reaction: keto-oxaloacetate = enol-oxaloacetate

Other name(s): oxalacetic keto-enol isomerase

Systematic name: oxaloacetate keto—enol-isomerase

Links to other databases: BRENDA, EXPASY, GTD, KEGG, Metacyc, CAS registry number: 37318-45-9

References:

1. Annett, R.G. and Kosicki, G.W. Oxalacetate keto-enol tautomerase. Purification and characterization. J. Biol. Chem. 244 (1969) 2059-2067. [PMID: 5781999]

[EC 5.3.2.2 created 1972]

EC 5.3.2.3

Accepted name: TDP-4-oxo-6-deoxy-α-D-glucose-3,4-oxoisomerase (dTDP-3-dehydro-6-deoxy-α-D-galactopyranose-forming)

Reaction: dTDP-4-dehydro-6-deoxy-α-D-glucopyranose = dTDP-3-dehydro-6-deoxy-α-D-galactopyranose

For diagram of reaction click here.

Other name(s): dTDP-6-deoxy-hex-4-ulose isomerase; TDP-6-deoxy-hex-4-ulose isomerase; FdtA

Systematic name: dTDP-4-dehydro-6-deoxy-α-D-glucopyranose:dTDP-3-dehydro-6-deoxy-α-D-galactopyranose isomerase

Comments: The enzyme is involved in the biosynthesis of dTDP-3-acetamido-3,6-dideoxy-α-D-galactose. Four moieties of α-D-rhamnose and two moities of 3-acetamido-3,6-dideoxy-α-D-galactose form the repeating unit of the glycan chain in the S-layer of the bacterium Aneurinibacillus thermoaerophilus.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:

References:

1. Pfoestl, A., Hofinger, A., Kosma, P. and Messner, P. Biosynthesis of dTDP-3-acetamido-3,6-dideoxy-α-D-galactose in Aneurinibacillus thermoaerophilus L420-91T. J. Biol. Chem. 278 (2003) 26410-26417. [PMID: 12740380]

2. Davis, M.L., Thoden, J.B. and Holden, H.M. The x-ray structure of dTDP-4-keto-6-deoxy-D-glucose-3,4-ketoisomerase. J. Biol. Chem. 282 (2007) 19227-19236. [PMID: 17459872]

[EC 5.3.2.3 created 2011]

EC 5.3.2.4

Accepted name: TDP-4-oxo-6-deoxy-α-D-glucose-3,4-oxoisomerase (dTDP-3-dehydro-6-deoxy-α-D-glucopyranose-forming)

Reaction: dTDP-4-dehydro-6-deoxy-α-D-glucopyranose = dTDP-3-dehydro-6-deoxy-α-D-glucopyranose

For diagram of reaction click here.

Other name(s): TDP-4-keto-6-deoxy-D-glucose-3,4-ketoisomerase (ambiguous); Tyl1a; dTDP-4-keto-6-deoxy-D-glucose-3,4-ketoisomerase (ambiguous)

Systematic name: dTDP-4-dehydro-6-deoxy-α-D-glucopyranose:dTDP-3-dehydro-6-deoxy-α-D-glucopyranose isomerase

Comments: The enzyme is involved in biosynthesis of D-mycaminose.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:

References:

1. Melancon, C.E., 3rd, Hong, L., White, J.A., Liu, Y.N. and Liu, H.W. Characterization of TDP-4-keto-6-deoxy-D-glucose-3,4-ketoisomerase from the D-mycaminose biosynthetic pathway of Streptomyces fradiae: in vitro activity and substrate specificity studies. Biochemistry 46 (2007) 577-590. [PMID: 17209568]

[EC 5.3.2.4 created 2011]

EC 5.3.2.5

Accepted name: 2,3-diketo-5-methylthiopentyl-1-phosphate enolase

Reaction: 5-(methylthio)-2,3-dioxopentyl phosphate = 2-hydroxy-5-(methylthio)-3-oxopent-1-enyl phosphate

Other name(s): DK-MTP-1-P enolase; MtnW; YkrW; RuBisCO-like protein; RLP

Systematic name: 2,3-diketo-5-methylthiopentyl-1-phosphate ketoenol-isomerase

Comments: The enzyme participates in the methionine salvage pathway in Bacillus subtilis [2]. In some species a single bifunctional enzyme, EC 3.1.3.77, acireductone synthase, catalyses both this reaction and EC 3.1.3.87, 2-hydroxy-3-keto-5-methylthiopentenyl-1-phosphate phosphatase [1].

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number:

References:

1. Myers, R.W., Wray, J.W., Fish, S. and Abeles, R.H. Purification and characterization of an enzyme involved in oxidative carbon-carbon bond cleavage reactions in the methionine salvage pathway of Klebsiella pneumoniae. J. Biol. Chem. 268 (1993) 24785-24791. [PMID: 8227039]

2. Ashida, H., Saito, Y., Kojima, C., Kobayashi, K., Ogasawara, N. and Yokota, A. A functional link between RuBisCO-like protein of Bacillus and photosynthetic RuBisCO. Science 302 (2003) 286-290. [PMID: 14551435]

[EC 5.3.2.5 created 2012]

EC 5.3.2.6

Accepted name: 2-hydroxymuconate tautomerase

Reaction: (2Z,4E)-2-hydroxyhexa-2,4-dienedioate = (3E)-2-oxohex-3-enedioate

For diagram of reaction click here.

Glossary: (2Z,4E)-2-hydroxyhexa-2,4-dienedioate = (2Z,4E)-2-hydroxymuconate

Other name(s): 4-oxalocrotonate tautomerase (misleading); 4-oxalocrotonate isomerase (misleading); cnbG (gene name); praC (gene name); xylH (gene name)

Systematic name: (2Z,4E)-2-hydroxyhexa-2,4-dienedioate ketoenol isomerase

Comments: Involved in the meta-cleavage pathway for the degradation of phenols, modified phenols and catechols. The enol form (2Z,4E)-2-hydroxyhexa-2,4-dienedioate is produced as part of this pathway and is converted to the keto form (3E)-2-oxohex-3-enedioate by the enzyme [6]. Another keto form, (4E)-2-oxohex-4-enedioate (4-oxalocrotonate), was originally thought to be produced by the enzyme [1,2] but later shown to be produced non-enzymatically [5].

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:

References:

1. Whitman, C.P., Aird, B.A., Gillespie, W.R. and Stolowich, N.J. Chemical and enzymatic ketonization of 2-hydroxymuconate, a conjugated enol. J. Am. Chem. Soc. 113 (1991) 3154-3162.

2. Whitman, C.P., Hajipour, G., Watson, R.J., Johnson, W.H., Jr., Bembenek, M.E. and Stolowich, N.J. Stereospecific ketonization of 2-hydroxymuconate by 4-oxalocrotonate tautomerase and 5-(carboxymethyl)-2-hydroxymuconate isomerase. J. Am. Chem. Soc. 114 (1992) 10104-10110.

3. Subramanya, H.S., Roper, D.I., Dauter, Z., Dodson, E.J., Davies, G.J., Wilson, K.S. and Wigley, D.B. Enzymatic ketonization of 2-hydroxymuconate: specificity and mechanism investigated by the crystal structures of two isomerases. Biochemistry 35 (1996) 792-802. [PMID: 8547259]

4. Stivers, J.T., Abeygunawardana, C., Mildvan, A.S., Hajipour, G., Whitman, C.P. and Chen, L.H. Catalytic role of the amino-terminal proline in 4-oxalocrotonate tautomerase: affinity labeling and heteronuclear NMR studies. Biochemistry 35 (1996) 803-813. [PMID: 8547260]

5. Wang, S.C., Johnson, W.H., Jr., Czerwinski, R.M., Stamps, S.L. and Whitman, C.P. Kinetic and stereochemical analysis of YwhB, a 4-oxalocrotonate tautomerase homologue in Bacillus subtilis: mechanistic implications for the YwhB- and 4-oxalocrotonate tautomerase-catalyzed reactions. Biochemistry 46 (2007) 11919-11929. [PMID: 17902707]

6. Kasai, D., Fujinami, T., Abe, T., Mase, K., Katayama, Y., Fukuda, M. and Masai, E. Uncovering the protocatechuate 2,3-cleavage pathway genes. J. Bacteriol. 191 (2009) 6758-6768. [PMID: 19717587]

[EC 5.3.2.6 created 2012]

EC 5.3.2.7

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 of reaction click here.

Glossary: ascopyrone M = 1,5-anhydro-4-deoxy-D-glycero-hex-3-en-2-ulose = (6S)-4-hydroxy-6-(hydroxymethyl)-2H-pyran-3(6H)-one
ascopyrone P = 1,5-anhydro-4-deoxy-D-glycero-hex-1-en-3-ulose = (2S)-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 Δ31-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].

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:

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]

[EC 5.3.2.7 created 2006 as EC 5.3.3.15, transferred 2012 to EC 5.3.2.7.]

EC 5.3.2.8

Accepted name: 4-oxalomesaconate tautomerase

Reaction: (1E)-4-oxobut-1-ene-1,2,4-tricarboxylate = (1E,3E)-4-hydroxybuta-1,3-diene-1,2,4-tricarboxylate

For diagram of reaction click here.

Glossary: (1E)-4-oxobut-1-ene-1,2,4-tricarboxylate = keto tautomer of 4-oxalomesaconate
(1E,3E)-4-hydroxybuta-1,3-diene-1,2,4-tricarboxylate = one of the enol tautomers of 4-oxalomesaconate

Other name(s): GalD

Systematic name: 4-oxalomesaconate ketoenol-isomerase

Comments: This enzyme has been characterized from the bacterium Pseudomonas putida KT2440 and is involved in the degradation pathway of syringate and gallate. It catalyses the interconversion of two of the tautomers of 4-oxalomesaconate, a reaction that can also occur spontaneously.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:

References:

1. Nogales, J., Canales, A., Jimenez-Barbero, J., Serra, B., Pingarron, J.M., Garcia, J.L. and Diaz, E. Unravelling the gallic acid degradation pathway in bacteria: the gal cluster from Pseudomonas putida. Mol. Microbiol. 79 (2011) 359-374. [PMID: 21219457]

[EC 5.3.2.8 created 2011 as 5.3.3.16, modified 2011, transferred 2012 to EC 5.3.2.8.]


Continued with EC 5.3.3 to EC 5.3.99
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