The fine structure of cassava starch amylopectin. Part 2: Building block structure of clusters

Abstract

The aim of this work was to analyse the organization of unit chains inside clusters of cassava amylopectin. beta-Limit dextrins of the clusters and partly fragmented clusters (sub-clusters) were isolated previously [Laohaphatanaleart et al., Int. J. Biol. Macromol. (2010) doi:10.1016/j.ijbiomac.2010.01.0049] and were now hydrolysed extensively with the alpha-amylase (liquefying type) of Bacillus subtilis into small, branched building blocks. The blocks were size-fractionated and characterized structurally. The smallest blocks predominated in the clusters. They were single branched and possessed a degree of polymerization (DP) of 5-9. Blocks with DP 10-15 were double branched and constituted the second largest group. The clusters of cassava amylopectin, which were of rather uniform size, possessed typically 7-9 building blocks, and all clusters contained similar size-distributions of the blocks. The inter-block chain length was 7-8 residues. The possible mode of attack by the enzyme between the building blocks is discussed. A model of the building block organization in the clusters is presented, in which the structural roles of different subgroups of clustered chains are suggested. A three-dimensional model suggests a possible organization of the building blocks inside the amorphous lamellae in the granular starch. (C) 2010 Elsevier B.V. All rights reserved.

Keywords

Amylopectin structure; Cluster structure; Building block structure

Published in

International Journal of Biological Macromolecules
2010, Volume: 47, number: 3, pages: 325-335 Publisher: ELSEVIER SCIENCE BV

SLU Authors

• Bertoft, Eric

  • Department of Molecular Sciences, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Food Science


Publication identifier

DOI: https://doi.org/10.1016/j.ijbiomac.2010.05.018

Permanent link to this page (URI)

https://res.slu.se/id/publ/47863