Determination of the Degree of Branching of Amylopectin-Like Glucans Evaluated by Quinoxaline Formation with o-Phenylenediamine under Alkaline and Deoxygenated Conditions

Abstract

Quinoxaline derivatives derived from glycogen and amylopectin-like glucans by treatment with acid or β-amylase, were used for evaluation of the degree of branching by an alkaline o-phenylenediamine (OPD) method. Ion-exchange resin column chromatography of quinoxalines derived from an amylopectin-β-limit dextrin showed that the glucan had an average chain length (C̅L̅) of 9.9 on the C-chain and 1.55 units of branched chains. A glycogen-β-limit dextrin had the C̅L̅ of 7.8 on the C-chain, with 2.38 units of branch. The degree of branching obtained from this alkaline OPD method agreed with those estimated by other conventional methods.