Reduction of the products of periodate oxidation of carbohydrates. VII. The constitution of glycogen

Abstract

Periodate oxidation of glycogen yields glycogen polyaldehyde which, upon reduction either with hydrogen and a palladium catalyst or with sodium borohydride, gives glycogen polyalcohol. Hydrolysis of the polyalcohol, obtained from glycogen samples of different origin, affords glycerol, erythritol, glycolic aldehyde, and glucose. Determination of the molar ratio of glycerol to erythritol which was approximately 1:10 provides a new route for the end-group assay of glycogen. The result by this new technique is in good agreement with those from periodate and methylation studies. The amount of glucose stable to periodate oxidation in various specimens of glycogen polyaldehyde and the corresponding polyalcohols was 0.6-0.7% of the parent glycogen. It is suggested that this glucose arises from d-glucose residues in the glycogen molecule that are linked so that they are immune to periodate cleavage. This observation appears to require a modification of the hitherto accepted structure of glycogen.