On the non-random nature of amylopectin branching

The cluster model of amylopectin (AP) provides a useful conceptual basis fo r understanding of the structure of the molecule, and this model guides cur rent thinking related to AP biosynthesis and physical behavior. The chain l ength profile of constituent linear regions of the molecule is commonly det ermined, and the cluster model guides the interpretation of results with an emphasis on the clustering of the linear regions of these chains. Less att ention has been given to the related but distinct question of the clusterin g of the branch points in AP. perhaps because this work is methodologically more difficult than for determination of the chain length profile and inte rpretation of the results is less straightforward. However, the unique aspe ct of AP is that its branching is non-random, and the physical properties o f AP may be considered to result from this unique structure. This review ad dresses the available information on the distribution of branch points in A P. Emphasis on this aspect of the cluster model has ramifications for futur e research on AP biosynthesis and AP physical behavior. (C) 2000 Elsevier S cience Ltd. All rights reserved.