The Properties of Synthetic Amylopectin with Long External‐Chains

Samples of synthetic amylopectins with long external chain‐lengths have been prepared from degraded, waxy maize amylopectin and glucose‐1‐phosphate by the action of potato phosphorylase. Samples having external chain‐lengths determined by enzymic assay of 23.4, 29.9, 46.5, and 109.5 glucose units (original sample = 13.7 glucose units) were prepared. The iodine‐staining properties of these materials have been investigated, and a relation between λmax and average chain‐length evaluated. A theoretical relation between chain‐length and β‐amylolysis limit has been proposed. The iodine‐binding capacity of the samples has been studied in detail by potentiometric titration at 1.5 °C and 20 °C. Unambiguous conclusions regarding the observed iodine binding capacity and the length of external chain have been made for the first time. The properties of the synthetic products are discussed.