title: Structures of clusters in sweetpotato amylopectin.
abstract: Sweetpotato amylopectin was subjected to partial hydrolysis by α-amylase from Bacillus amyloliquefaciens to release the clusters. Clusters were then fractionated and precipitated by methanol and structurally characterized by gel-permeation chromatography and high-performance anion-exchange chromatography. An initial stage of α-amylolysis on the amylopectin isolated mostly domains but also clusters. A second stage of α-amylolysis on the domains and clusters further isolated their respective clusters and sub-clusters. All the domains, clusters and sub-clusters were sequentially subjected to phosphorolysis and β-amylolysis to obtain their internal part. The degree of polymerization of the clusters in the form of φ,β-limit dextrins were from 58 to 86. Each domain contained 2-8 clusters. Two types of clusters were structurally identified. Type A clusters were larger and contained about 12 chains per cluster with higher degree of branching (DB), whereas those of type B were smaller and contained about eight chains per cluster with lower DB.
authors.affiliation: School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China. fzhu5@yahoo.com
authors.forename: Fan
authors.initials: F
authors.lastname: Zhu
authors.forename: Harold
authors.initials: H
authors.lastname: Corke
authors.forename: Per
authors.initials: P
authors.lastname: Åman
authors.forename: Eric
authors.initials: E
authors.lastname: Bertoft
mesh_terms: D000687:Amylopectin / Q000737:chemistry*; D002236:Carbohydrate Conformation; D005591:Chemical Fractionation; D027723:Ipomoea batatas / Q000737:chemistry*
chemical_list: D000687:Amylopectin