IUBMB Enzyme Nomenclature


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 = (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 (aldos-2-ulose dehydratase), EC [exo-(1→4)-α-D-glucan lyase] and EC (ascopyrone tautomerase). Requires divalent (Ca2+ or Mg2+) or monovalent cations (Na+) for optimal activity. Unlike EC, 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

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


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]

[EC created 2006]

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