Cereal Chem 57:12 - 16.  |  VIEW ARTICLE
Debranching of Wheat Amylopectin.

W. A. Atwell, R. C. Hoseney, and D. R. Lineback. Copyright 1980 by the American Association of Cereal Chemists, Inc. 

Gel chromatographic evidence indicates that the bimodal distribution of chains obtained from debranching wheat amylopectin probably results from a single, normal population of amylopectin molecules. Amylopectin beta-limit dextrin has a normal distribution when eluted from a Sepharose CL-4B column. When aliquots from the leading and trailing edges of this distribution were debranched with pullulanase and subjected to Bio-Gel P-10 chromatography, debranched amylopectin's bimodal distribution was preserved. A third peak, composed of maltose and maltotriose derived from beta-amylase-hydrolyzed A chains, was also observed. In addition, comparison of the chain profiles of native amylopectin and beta-limit dextrin showed that the peak corresponding to the shorter average chain length material (amylopectin) was hydrolyzed more than the peak corresponding to the longer average chain length material (beta-limit dextrin). The modes of attack of pullulanase and isoamylase on amylopectin also differed. Pullulanase yields the bimodal distribution of chains throughout the degradation of amylopectin. Isoamylase, however, quickly reduces the polymer to intermediate fractions, which are in turn further debranched to form the bimodal distribution.