STRUCTURES OF THE AMYLOPECTINS OF WAXY, NORMAL, AMYLOSE-EXTENDER, ANDWX-AE GENOTYPES AND OF THE PHYTOGLYCOGEN OF MAIZE

Average chain lengths and beta-amylolysis limits have been determined for the waxy and ae/wx genotypes of mature maize starch, and for the a mylopectin fractions of normal and amylose-extender starches (prepared by precipitation with concanavalin A), rabbit-liver glycogen, phytogl ycogen, and waxy rice starch. All amylopectin samples had similar A:B chain ratios of > 1 and the two glycogens had ratios of < 1. This find ing led to average frequencies of substitution of B chains over the wh ole molecule of > 2 for the amylopectins and < 2 for the glycogens. An equation for the number of tiers for a molecule with various frequenc ies of substitution of B chains and chain lengths has been used to det ermine the effect of variation in average frequency of branching and a verage chain length on structure.