The Enzyme Database

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EC 1.1.1.263     
Accepted name: 1,5-anhydro-D-fructose reductase
Reaction: 1,5-anhydro-D-glucitol + NADP+ = 1,5-anhydro-D-fructose + NADPH + H+
Systematic name: 1,5-anhydro-D-glucitol:NADP+ oxidoreductase
Comments: Also reduces pyridine-3-aldehyde and 2,3-butanedione. Acetaldehyde, 2-dehydroglucose (glucosone) and glucuronate are poor substrates, but there is no detectable action on glucose, mannose and fructose.
Links to other databases: BRENDA, EAWAG-BBD, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 206138-19-4
References:
1.  Sakuma, M., Kametani, S. and Akanuma, H. Purification and some properties of a hepatic NADPH-dependent reductase that specifically acts on 1,5-anhydro-D-fructose. J. Biochem. (Tokyo) 123 (1998) 189–193. [PMID: 9504428]
[EC 1.1.1.263 created 2000]
 
 
EC 1.1.1.292     
Accepted name: 1,5-anhydro-D-fructose reductase (1,5-anhydro-D-mannitol-forming)
Reaction: 1,5-anhydro-D-mannitol + NADP+ = 1,5-anhydro-D-fructose + NADPH + H+
Other name(s): 1,5-anhydro-D-fructose reductase (ambiguous); AFR (ambiguous)
Systematic name: 1,5-anhydro-D-mannitol:NADP+ oxidoreductase
Comments: This enzyme is present in some but not all Rhizobium species and belongs in the GFO/IDH/MocA protein family [2]. This enzyme differs from hepatic 1,5-anhydro-D-fructose reductase, which yields 1,5-anhydro-D-glucitol as the product (see EC 1.1.1.263). In Sinorhizobium morelense, the product of the reaction, 1,5-anhydro-D-mannitol, can be further metabolized to D-mannose [1]. The enzyme also reduces 1,5-anhydro-D-erythro-hexo-2,3-diulose and 2-ketoaldoses (called osones), such as D-glucosone (D-arabino-hexos-2-ulose) and 6-deoxy-D-glucosone. It does not reduce common aldoses and ketoses, or non-sugar aldehydes and ketones [1].
Links to other databases: BRENDA, EAWAG-BBD, EXPASY, KEGG, MetaCyc, PDB
References:
1.  Kühn, A., Yu, S. and Giffhorn, F. Catabolism of 1,5-anhydro-D-fructose in Sinorhizobium morelense S-30.7.5: discovery, characterization, and overexpression of a new 1,5-anhydro-D-fructose reductase and its application in sugar analysis and rare sugar synthesis. Appl. Environ. Microbiol. 72 (2006) 1248–1257. [DOI] [PMID: 16461673]
2.  Dambe, T.R., Kühn, A.M., Brossette, T., Giffhorn, F. and Scheidig, A.J. Crystal structure of NADP(H)-dependent 1,5-anhydro-D-fructose reductase from Sinorhizobium morelense at 2.2 Å resolution: construction of a NADH-accepting mutant and its application in rare sugar synthesis. Biochemistry 45 (2006) 10030–10042. [DOI] [PMID: 16906761]
[EC 1.1.1.292 created 2007]
 
 
EC 4.2.1.110     
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 of the anhydrofructose pathway, 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]. 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), is inhibited by its product and requires metal ions for activity [1].
Links to other databases: BRENDA, EAWAG-BBD, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 101920-80-3
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. [DOI] [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. [DOI] [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. [DOI] [PMID: 15110094]
[EC 4.2.1.110 created 2006]
 
 
EC 4.2.1.111     
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 of the anhydrofructose pathway, 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
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; 1,5-anhydro-D-fructose hydro-lyase
Systematic name: 1,5-anhydro-D-fructose hydro-lyase (ascopyrone-M-forming)
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 5.3.2.7 (ascopyrone tautomerase). Requires divalent (Ca2+ or Mg2+) or monovalent cations (Na+) for optimal activity. Unlike EC 4.2.1.110, 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.
Links to other databases: BRENDA, EAWAG-BBD, EXPASY, KEGG, MetaCyc
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. [DOI] [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. [DOI] [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. [DOI] [PMID: 15716041]
[EC 4.2.1.111 created 2006]
 
 
EC 4.2.2.13     
Accepted name: exo-(1→4)-α-D-glucan lyase
Reaction: linear α-glucan = (n-1) 1,5-anhydro-D-fructose + D-glucose
For diagram of the anhydrofructose pathway, click here
Other name(s): α-(1→4)-glucan 1,5-anhydro-D-fructose eliminase; α-1,4-glucan exo-lyase; α-1,4-glucan lyase; GLase
Systematic name: (1→4)-α-D-glucan exo-4-lyase (1,5-anhydro-D-fructose-forming)
Comments: The enzyme catalyses the sequential degradation of (1→4)-α-D-glucans from the non-reducing end with the release of 1,5-anhydro-D-fructose. Thus, for an α-glucan containing n (1→4)-linked glucose units, the final products are 1 glucose plus (n-1) 1,5-anhydro-D-fructose. Maltose, maltosaccharides and amylose are all completely degraded. It does not degrade (1→6)-α-glucosidic bonds and thus the degradation of a branched glucan, such as amylopectin or glycogen, will result in the formation of 1,5-anhydro-D-fructose plus a limit dextrin. Other enzymes involved in the anhydrofructose pathway are EC 4.2.1.110 (aldos-2-ulose dehydratase), EC 4.2.1.111 (1,5-anhydro-D-fructose dehydratase) and EC 5.3.2.7 (ascopyrone tautomerase).
Links to other databases: BRENDA, EAWAG-BBD, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 148710-18-3
References:
1.  Yu, S., Kenne, L., Pedersén, M. α-1,4-Glucan lyase, a new class of starch/glycogen degrading enzyme. I. Efficient purification and characterization from red seaweeds. Biochim. Biophys. Acta 1156 (1993) 313–320. [DOI] [PMID: 8461323]
2.  Yu, S., Pedersén, M. α-1,4-Glucan lyase, a new class of starch/glycogen degrading enzyme. II. Subcellular localization and partial amino-acid sequence. Planta 191 (1993) 137–142. [PMID: 7763826]
3.  Yu, S., Ahmad, T., Kenne, L. and Pedersén, M. α-1,4-Glucan lyase, a new class of starch/glycogen degrading enzyme. III. Substrate specificity, mode of action, and cleavage mechanism. Biochim. Biophys. Acta 1244 (1995) 1–9. [DOI] [PMID: 7766642]
4.  Yu, S., Christensen, T.M., Kragh, K.M., Bojsen, K. and Marcussen, J. Efficient purification, characterization and partial amino acid sequencing of two α-1,4-glucan lyases from fungi. Biochim. Biophys. Acta 1339 (1997) 311–320. [DOI] [PMID: 9187252]
5.  Yu, S., Bojsen, K., Svensson, B. and Marcussen, J. α-1,4-glucan lyases producing 1,5-anhydro-D-fructose from starch and glycogen have sequence similarity to α-glucosidases. Biochim. Biophys. Acta 1433 (1999) 1–15. [DOI] [PMID: 10446355]
6.  Lee, S.S., Yu, S. and Withers, S.G. α-1,4-Glucan lyase performs a trans-elimination via a nucleophilic displacement followed by a syn-elimination. J. Am. Chem. Soc. 124 (2002) 4948–4949. [DOI] [PMID: 11982345]
7.  Lee, S.S., Yu, S. and Withers, S.G. Detailed dissection of a new mechanism for glycoside cleavage: α-1,4-glucan lyase. Biochemistry 42 (2003) 13081–13090. [DOI] [PMID: 14596624]
[EC 4.2.2.13 created 1999]
 
 
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 the anhydrofructose pathway, 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 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].
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
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. [DOI] [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. [DOI] [PMID: 16822618]
[EC 5.3.2.7 created 2006 as EC 5.3.3.15, transferred 2012 to EC 5.3.2.7]
 
 
EC 5.3.3.15      
Transferred entry: ascopyrone tautomerase. Now EC 5.3.2.7, ascopyrone tautomerase
[EC 5.3.3.15 created 2006, deleted 2013]
 
 


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