STUDIES ON THE STRUCTURE OF PEA STARCHES .3. AMYLOPECTIN OF SMOOTH PEA STARCH

beta-Limit dextrins were isolated from smooth pea starch. It was shown by gel chromatography that the sample contained smaller limit dextrins with a degree of polymerization (D.P.) of 40-4000 in addition to high-molecular-weight material. The smooth pea starch and the beta-limit dextrins were hydrolysed by the alpha-amylase of B. amyloliquefaciens and the molecular weight distribution of the reaction mixtures was analysed on Sepharose CL 6B. Initially the reaction was fast, but at later stages branched dextrins with 10 similar to 60 were only very slowly hydrolysed further. In addition, linear dextrins with d.p. 2-10 were formed continously. Based on the branched dextrins produced from the beta-limit dextrins a model of the structure of the amylopectin component in smooth pea starch is suggested, in which clusters of defined sizes are regularly interconnected.