| Abstract: | Light-scattering, viscosity and ultracentrifugal techniques have been applied to a number of amylopectin samples. These measurements have confirmed the very large size of the macromolecule, and shown that such values are real, and are not due to aggregation resulting from hydrogen-bonding. The hydrodynamic behaviour of amylopectin has been compared with that of the closely-related glycogen. The difference between the two has been shown to be due to the much more flexible, coil-like nature of the amylopectin. An examination has been made of the factors governing the extension of amylopectin as the pH is varied, and it is shown that under appropriate solvent conditions a “coil-to-helix” transformation may be observed. The conformation of the amylopectin molecule is discussed, and the concept that the macromolecule is a two-dimensional entity is proposed. |
