Enzymic methods for the microdetermination of glycogen and amylopectin, and their unit-chain lengths

Methods for the microdetermination of glycogen and amylopectin and their average unit-chain lengths are described. The determination of the polysaccharides relies on their quantitative conversion into glucose by amyloglucosidase. The chainlength determination requires the simultaneous use of two enzymes, pullulanase and β-amylase, for the complete degradation of the polysaccharides to maltose and glucose. The specific measurement of the glucose formed permits the calculation of chain length. The methods were tested with samples of glycogen and amylopectin, whose chain lengths had been determined by periodate oxidation. In all cases there was good agreement between the results of the chemical and enzymic determinations. The analyses may be performed with less than 1 mg of polysaccharide, and so are particularly appropriate to the examination of glycogen in biopsy specimens.