MetaCyc

Parent Class:

EC-Numbers → 4 -- Lyases → 4.2 -- Carbon-oxygen lyases → 4.2.2 -- Acting on polysaccharides

Synonyms: inulin fructotransferase (DFA-III-producing), inulin fructotransferase (depolymerizing), inulase II, inulinase II, inulin fructotransferase (depolymerizing, difructofuranose-1,2′:2,3′-dianhydride-forming), inulin D-fructosyl-D-fructosyltransferase (1,2′:2,3′-dianhydride-forming), inulin D-fructosyl-D-fructosyltransferase (forming α-D-fructofuranose β-D-fructofuranose 1,2′:2,3′-dianhydride), 2,1-β-D-fructan lyase (α-D-fructofuranose-β-D-fructofuranose-1,2′:2,3′-dianhydride-forming)

Systematic Name: (2→1)-β-D-fructan lyase (α-D-fructofuranose-β-D-fructofuranose-1,2′:2,3′-dianhydride-forming)

Unification Links: BRENDA:4.2.2.18, ENZYME:4.2.2.18, IUBMB-ExplorEnz:4.2.2.18

Supersedes EC number: 2.4.1.93

Reaction:
a [1-β-D-fructofuranosyl-(2->1)_n--α-D-glucopyranoside → a [1-β-D-fructofuranosyl-(2->1)_n-1--α-D-glucopyranoside + difructose anhydride III

Enzymes and Genes:
inulin fructotransferase/DFA-IIIase: Achl_2895 ( Pseudarthrobacter chlorophenolicus )

Summary:
This enzyme, like EC 4.2.2.16, levan fructotransferase (DFA-IV-forming) and EC 4.2.2.17, inulin fructotransferase (DFA-I-forming), eliminates the fructan chain from the terminal disaccharide leaving a difructose dianhydride. These enzymes have long been known as fructotransferases, so this is retained in the accepted name. Since the transfer is intramolecular, the reaction is an elimination and, hence, the enzyme is a lyase, belonging in EC 4.

Citations: [Uchiyama73, Uchiyama75, Haraguchi00, Kim07f, Haraguchi13]