ULTRASTRUCTURE AND PHYSICO-CHEMICAL PROPERTIES OF GLYCOGEN FROM ASCITES HEPATOMA AH13

Abstract

Ultrastructural appearances and physico-chemical properties of ascites hepatoma AH13 glycogen were studied and compared with those of the muscle and liver glycogen. In the electron microscopy, the AH13 glycogen particles were demonstrated in various forms, some of which were similar to the muscle or liver glycogen, and the other had strong resemblance to the polyglucose which was synthesized from uridine diphosphate glucose by glycogen synthetase in the muscle fiber. Sometimes, there was the characteristic figure in part of the particles.End group assay of the AH13 glycogen products exhibited the average chain length of intermediate value between both the liver and muscle glycogen. The optical rotatory dispersion and circular dichroism spectra of AH13 glycogen, measured in addition of iodine, showed the positive Cotton effect was stronger than the muscle glycogen. This Cotton effect was discussed relation to variation of temperature from 10°C to 85°C.The glycogen-iodine complex presumably indicated not only the chain length, but also the chain helical structure, affecting by the temperature. The sedimentation coefficients, calculated for AH13 glycogen, depended on the sample concentration. Schlieren diagrams showed the sharpness of the curves on the photographs. It was suspected from the results that the interwinement of the chain of α-1, 4-linked glucose units and the linkage of the chain tended to occur more easily in case of high concentration of the sample during ultracentrifugation. This presumably resulted from the deviation of glycogen metabolism in tumor cells. These facts suggested the specific chain conformation without protein-bonded aggregation as proposed by Lazarow (9).