Title: Fructan 1-exohydrolases. beta-(2,1)-trimmers during graminan biosynthesis in stems of wheat? Purification, characterization, mass mapping, and cloning of two fructan 1-exohydrolase isoforms
Authors: Van den Ende, Wim ×
Clerens, Stefan
Vergauwen, Rudolf
Van Riet, Liesbet
Van Laere, André
Yoshida, M
Kawakami, A #
Issue Date: Feb-2003
Publisher: Amer soc plant biologists
Series Title: Plant physiology vol:131 issue:2 pages:621-631
Abstract: Graminan-type fructans are temporarily stored in wheat (Triticum aestivum) stems. Two phases can be distinguished: a phase of fructan biosynthesis (green stems) followed by a breakdown phase (stems turning yellow). So far, no plant fructan exohydrolase enzymes have been cloned from a monocotyledonous species. Here, we report on the cloning, purification, and characterization of two fructan I-exohydrolase cDNAs (1-FEH w1 and w2) from winter wheat stems. Similar to dicot plant I-FEHs, they are derived from a special group within the cell wall-type invertases characterized by their low isoelectric points. The corresponding isoenzymes were purified to electrophoretic homogeneity, and their mass spectra were determined by quadrupole-time-of-flight mass spectrometry. Characterization of the purified enzymes revealed that inulin-type fructans [beta-(2,1)] are much better substrates than levan-type fructans [beta-(2,6)]. Although both enzymes are highly identical (98% identity), they showed different substrate specificity toward branched wheat stem fructans. Although 1-FEH activities were found to be considerably higher during the fructan breakdown phase, it was possible to purify substantial amounts of 1-FEH w2 from young, fructan biosynthesizing wheat stems, suggesting that this isoenzyme might play a role as a beta-(2,1)-trimmer throughout the period of active graminan biosynthesis. In this way, the species and developmental stage-specific complex fructan patterns found in monocots might be determined by the relative proportions and specificities of both fructan biosynthetic and breakdown enzymes.
ISSN: 0032-0889
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Molecular Physiology of Plants and Micro-organisms Section - miscellaneous
Animal Physiology and Neurobiology Section - miscellaneous
× corresponding author
# (joint) last author

Files in This Item:

There are no files associated with this item.

Request a copy


All items in Lirias are protected by copyright, with all rights reserved.

© Web of science