FRUCTAN EXOHYDROLASE ACTIVITIES FROM LOLIUM-RIGIDUM THAT HYDROLYZE BETA-2,1-GLYCOSIDIC AND BETA-2,6-GLYCOSIDIC LINKAGES AT DIFFERENT RATES

Five fructan exohydrolase activities from Lolium rigidum Gaudin were s eparated and partly purified by a combination of salt precipitation, a ffinity chromatography, gel-filtration chromatography, anion-exchange chromatography and isoelectric focusing. The activities were identifie d by incubating enzyme fractions with fructan from both Lolium rigidum and Cichorium intybus. On the basis of activities when (6,6,6)-kestop entaose and (1,1,1)-kestopentaose were used as substrates, it was conc luded that three of the activities hydrolyzed beta-2,6-glycosidic link ages faster than beta-2,1-glycosidic linkages and two activities hydro lyzed beta-2,1-glycosidic linkages faster than beta-2,6-glycosidic lin kages. Fructan exohydrolases that hydrolyze beta-2,1-glycosidic linkag es faster than beta-2,6-glycosidic linkages, and fructan exohydrolases that hydrolyze beta-2,6-glycosidic linkages faster than beta-2,1-glyc osidic linkages have not previously been identified together in a temp erate grass. All fructan exohydrolases were inhibited markedly by sucr ose. It is proposed that the classification of beta-fructofuranosidase s be reconsidered because EC 3.2.1.80 is presently used to designate a ll fructan exohydrolases irrespective of the rates at which they hydro lyze beta-2,1- or beta-2,6-glycosidic linkages in fructans.