IUBMB Enzyme Nomenclature


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 (aldos-2-ulose dehydratase), EC (1,5-anhydro-D-fructose dehydratase) and EC [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:


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 created 2006 as EC, transferred 2012 to EC]

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