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Updated: Jun 21, 2026

Determination of Glucan Chain Length Distribution of Glycogen Using the Fluorophore-Assisted Carbohydrate Electrophoresis (FACE) Method
Published on: March 31, 2022
Glucosylation of raffinose via alternansucrase acceptor reactions
Gregory L Côté1, Christopher A Dunlap, Karl E Vermillion
1National Center for Agricultural Utilization Research, United States Department of Agriculture, Peoria, IL 61604, USA. greg.cote@ars.usda.gov
Abstract:
The glucansucrase known as alternansucrase [EC 2.4.1.140] can transfer glucosyl units from sucrose to raffinose to give good yields of oligosaccharides, which may serve as prebiotics. The main products were the tetrasaccharides alpha-d-Glcp-(1-->3)-alpha-d-Galp-(1-->6)-alpha-d-Glcp-(1<-->2)-beta-d-Fruf and alpha-d-Glcp-(1-->4)-alpha-d-Galp-(1-->6)-alpha-d-Glcp-(1<-->2)-beta-d-Fruf in ratios ranging from 4:1 to 9:1, along with lesser amounts of alpha-d-Glcp-(1-->6)-alpha-d-Galp-(1-->6)-alpha-d-Glcp-(1<-->2)-beta-d-Fruf. Ten unusual pentasaccharide structures were isolated. Three of these arose from glucosylation of the major tetrasaccharide product, two each from the minor tetrasaccharides, and three were the result of glucosylations of the fructose acceptor product leucrose or isomaltulose. The major pentasaccharide product arose from glucosylation of the major tetrasaccharide at position 4 of the fructofuranosyl unit, to give a subunit structure analogous to that of maltulose. A number of hexasaccharides and higher oligosaccharides were also produced. Unlike alternansucrase, dextransucrase [EC 2.4.1.5] gave only a single tetrasaccharide product in low yield, and no significant amounts of higher oligosaccharides. The tetrasaccharide structure from dextransucrase was found to be alpha-d-Glcp-(1-->4)-alpha-d-Galp-(1-->6)-alpha-d-Glcp-(1<-->2)-beta-d-Fruf, which is at odds with the previously published structure.
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