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¡ú4)-¦Á-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, 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 the end-product ascopyrone M into microthecin, as can EC?4.2.1.110.
