STRUCTURAL-ANALYSIS ON THE AMYLOPECTIN OF WAXY-BARLEY LARGE STARCH GRANULES

The hydrolysis of waxy-barley starch by the alpha-amylase of B. subtilis was followed by gel chromatography on Sepharose CL 6B. A range of intermediate dextrins were initially produced, and at later stages dextrins with a degree of polymerization in the range 100-200 accumulated. Maltohexaose was produced simultaneously f rom the external chains. The hydrolysis of the amylopectin beta-limit dextrin followed a similar pattern, though smaller amounts of the low-molecular weight material were formed. The sizes of the more resistant products in the hydrolysis mixtures suggested that the amylopectin contained two types of unit clusters with d.p. for the beta-limit dextrins of 65 and 85. A regular model for the structure of the amylopectin that shows the possible mode of interconnection of the unit clusters is presented.