Produces alpha-D-fructofuranose beta-D-fructofuranose 1,2':2,1'-dianhydride (DFA I) 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 4.2.2.18 [inulin fructotransferase (DFA-III-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 4.2.2.17 created 1992 as EC 2.4.1.200, transferred 2004 to EC 4.2.2.17
