A PERIODIC DISTRIBUTION OF THE CHAIN-LENGTH OF AMYLOPECTIN AS REVEALED BY HIGH-PERFORMANCE ANION-EXCHANGE CHROMATOGRAPHY

The chains of amylopectin over dp 80 were separated on baseline resolu tion by high-performance anion-exchange chromatography with pulsed amp erometric detection under improved conditions, and the chain-length (c l) distributions of amylopectins from eleven plant sources were analyz ed. The differences in amount of each chain between arrowhead (Sagitta ria trifolia L. var. sinensis Makino) and other kinds of amylopectins exhibited periodic waves which divided the abscissa at intervals of dp 12, except those of edible canna and yam amylopectins, where the inte rval was of the order of dp 15. Accordingly, chain-length distribution s were fractionated into fa, dp 6-12; fb(1), dp 13-24; fb(2), dp 25-36 , and fb(3), dp > 37. Amylopectin with short and long <(cl)over bar>(n ) had large and small amounts of the fa fraction, respectively, and sh owed A and B type X-ray diffractions of starch granules. The amount of the fa fraction was suggested to play an important role in the determ ination of starch crystalline polymorphs.