Fructan exohydrolase activities from Lolium rigidum that hydrolyze β‐2, 1‐ and β‐2, 6‐glycosidic linkages at different rates

SUMMARY Five fructan exohydrolase activities from Lolium rigidum Gaudin were separated and partly purified by a combination of salt precipitation, affinity chromatography, gel‐filtration chromatography, anion‐exchange chromatography and isoelectric focusing. The activities were identified by incubating enzyme fractions with fructan from both Lolium rigidum and Cichorium intybus. On the basis of activities when (6,6,6)‐kestopentaose and (1,1,1)‐kestopentaose were used as substrates, it was concluded that three of the activities hydrolyzed β‐2, 6‐glycosidic linkages faster than β‐2,l‐glycosidic linkages and two activities hydrolyzed β‐2,l‐glycosidic linkages faster than β‐2, 6‐glycosidic linkages. Fructan exohydrolases that hydrolyze β‐2,l‐glycosidJc linkages faster than β‐2, 6‐glycosidic linkages, and fructan exohydrolases that hydrolyze β‐2, 6‐glycosidic linkages faster than β‐2,1‐ glycosidic linkages have not previously been identified together in a temperate grass. All fructan exohydrolases were inhibited markedly by sucrose. It is proposed that the classification of β‐fructofuranosidases be reconsidered because EC 3.2.1. 80 is presently used to designate all fructan exohydrolases irrespective of the rates at which they hydrolyze β‐2, 6 or β‐2, 6‐glycosidic linkages in fructans.