Physiologia plantarum vol:97 issue:2 pages:346-352
Besides the non-reducing inulin series of gluco-fructo oligosaccharides which are common in Asteraceae, two series of reducing fructofuranosyl-only oligosaccharides occur in overwintering, forced, and sprouting chicory roots. Such inulo-n-oses could br produced by the action of an endo-inulinase on gluco-fructo oligosaccharides. We show here that similar series of inulo-n-oses as found in vivo can be produced by incubating fructose and inulin with a purified fructan:fructan fructosyl transferase (FFT; EC 188.8.131.52) from chicory roots (Cichorium intybus L.). Therefore fructose (but not glucose) can act as an acceptor for FFT. Since the inulo-n-oses only appear in vivo once the endogenous fructose concentration increases, we conclude that they are not the result of a putative endo-inulinase but of FFT activity.