KEGG   ENZYME: 4.2.2.18Help
Entry
EC 4.2.2.18                 Enzyme                                 

Name
inulin fructotransferase (DFA-III-forming);
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 alpha-D-fructofuranose beta-D-fructofuranose 1,2':2,3'-dianhydride);
2,1-beta-D-fructan lyase (alpha-D-fructofuranose-beta-D-fructofuranose-1,2':2,3'-dianhydride-forming)
Class
Lyases;
Carbon-oxygen lyases;
Acting on polysaccharides
BRITE hierarchy
Sysname
(2->1)-beta-D-fructan lyase (alpha-D-fructofuranose-beta-D-fructofuranose-1,2':2,3'-dianhydride-forming)
Reaction(IUBMB)
Produces alpha-D-fructofuranose beta-D-fructofuranose 1,2':2,3'-dianhydride (DFA III) by successively eliminating the diminishing (2->1)-beta-D-fructan (inulin) chain from the terminal D-fructosyl-D-fructosyl disaccharide.
Comment
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.
History
EC 4.2.2.18 created 1976 as EC 2.4.1.93, transferred 2004 to EC 4.2.2.18
Reference
1  [PMID:1148257]
  Authors
Uchiyama T.
  Title
Action of Arthrobacter ureafaciens inulinase II on several oligofructans and bacterial levans.
  Journal
Biochim. Biophys. Acta. 397 (1975) 153-63.
Reference
2
  Authors
Uchiyama, T., Niwa, S. and Tanaka, K.
  Title
Purification and properties of Arthrobacter ureafaciens inulase II.
  Journal
Biochim. Biophys. Acta 315 (1973) 412-420.
Other DBs
ExplorEnz - The Enzyme Database: 
IUBMB Enzyme Nomenclature: 
ExPASy - ENZYME nomenclature database: 
BRENDA, the Enzyme Database: 
CAS: 
50936-42-0

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