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

Abstract

The hydrolysis of waxy-barley starch by the α-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 from the external chains. The hydrolysis of the amylopectin β-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 β-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.