title: Structure of clusters and building blocks in amylopectin from developing wheat endosperm.
abstract: Changes in internal structure of amylopectin (AP) during wheat endosperm development were studied by isolating clusters and building blocks of AP from both large A-type and small B-type starch granules at different maturity stages up to harvest time at 49 days after anthesis (DAA). Clusters isolated from B-type granules had a degree of branching (DB) of 16.5-16.8% and were more tightly branched than those isolated from A-type granules (DB 15.7-16.2%). The degree of polymerization (DP) of the clusters increased in both types of granules during the pre-physiological maturity stage up to 28 DAA. Clusters at maturity were smaller with less branches and building blocks than at the end of the pre-maturity stage. It is suggested that this was due to a continuous trimming of the cluster structure after the active period of starch synthesis. Differences were evident between A- and B-type granules with regards to glucan trimming and the type of new chains produced.
authors.affiliation: Department of Food Science, University of Guelph, Guelph, ON N1G 2W1, Canada.
authors.forename: Danusha N
authors.initials: DN
authors.lastname: Kalinga
authors.affiliation: Department of Food Science and Nutrition, University of Minnesota, St. Paul, MN 55108, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Bertoft
authors.affiliation: Department of Molecular and Cellular Biology, Science Complex, University of Guelph, Guelph, ON N1G 2W1, Canada.
authors.forename: Ian
authors.initials: I
authors.lastname: Tetlow
authors.affiliation: Department of Food Science and Nutrition, University of Minnesota, St. Paul, MN 55108, USA. Electronic address: kseethar@umn.edu.
authors.forename: Koushik
authors.initials: K
authors.lastname: Seetharaman
mesh_terms: D000687:Amylopectin / Q000737:chemistry*; D056625:Endosperm / Q000737:chemistry*; D013213:Starch / Q000737:chemistry; D014908:Triticum / Q000737:chemistry* / Q000254:growth & development
chemical_list: D013213:Starch; D000687:Amylopectin
keywords: Amylopectin; Building blocks; Clusters; Developing endosperm; Wheat starch