Structure\nof Branched Subunits in the Amylopectins\nof Starches Varying in Polymorphism

Amylopectins from model starches of different polymorphisms\n(A-type\nmaize, C<sub>A</sub>-type lotus seed, and B-type potato) were characterized\nwith regard to the molecular structure of their branched subunits\n(clusters and building blocks). Lotus seed and maize clusters had\nlarger sizes, shorter average chain lengths, higher branching densities,\nand shorter interblock chain lengths than potato clusters. Lotus seed\nand maize clusters were different in their composition of short internal\nchains. Lotus seed clusters consisted of fewer singly branched blocks\nand more doubly branched blocks than maize clusters. The clusters\nisolated from the two lotus seed amylopectins had similar chain length\ndistribution but different building block compositions. The interbranch\nchain length was considered important in shaping starch polymorphism.\nStarch polymorphism might be related not only to the densely branched\nsubunits of amylopectin but also to the loosely branched ones. In\naddition, this study exemplified a light-scattering-based method as\nan alternative for the size characterization of amylopectin branched\nsubunits.