A light scattering study of corn amylopectin and its beta‐amylase limit dextrin

The degree of dispersion of a corn amylopectin and its ß‐amylase limit dextrin was studied in 1 N alkali, anhydrous ethylenediamine, ethylenediamine hydrate, formamide, and water by means of measurements of the concentration and angular dependence of scattered light. It was found that the degree of dispersion in the first three solvents is essentially the same for both preparations. The molecular weight of the amylopectin and limit dextrin are 80 million and 29 million, respectively. This result is in agreement within experimental error with the ratio of molecular weights to be expected on the basis of the known degree of degradation by ß‐amylase, and supports the view that essentially molecular dispersions were obtained. The agreement further indicates that the molecular weight distributions of the amylopectin and limit dextrin are similar in form. With this assumption and the radii of gyration of the materials, 2090 and 1340 A., it is concluded that the simplest model consistent with the data is a spherically symmetrical distribution of segments with segment density decreasing with r .