A single step polarographic assay of glycogen in muscle tissue and a note on the action of amyloglucosidase.

A rapid, single step polarographic assay of glycogen in KOH digests of muscle is presented. Amyloglucosidase is used to hydrolyse the glycogen to glucose, which is then immediately reacted with glucose oxidase. The method has a good reproducibility, is rapid, and requires as little as 0.7 mg freeze-dried muscle powder. From comparison of the rate of reaction of glycogen in the complete assay mixture with those of alpha- and beta-D-glucose, it was concluded that in the hydrolysis of glycogen--a polymer of alpha-D-glucose--by amyloglucosidase, the immediate and only product is beta-D-glucose. This suggests that during hydrolysis, the pyranose ring is opened at carbon 1, and that carbon 1 is rotated to the beta-configuration before closure.