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 resolution by high-performance anion-exchange chromatography with pulsed amperometric detection under improved conditions, and the chain-length (cl) distributions of amylopectins from eleven plant sources were analyzed. The differences in amount of each chain between arrowhead (Sagittaria 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 interval was of the order of dp 15. Accordingly, chain-length distributions 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 showed 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 determination of starch crystalline polymorphs.