Ultrastructural and physicochemical studies on glycogen macromolecules from ascites hepatoma AH 13 cells. A comparison with normal adult rat muscle, liver and fetal liver glycogen.

Glycogen extracted from rat ascites hepatoma AH 13 cells was compared with that from adult rat liver, adult rat muscle, and fetal rat liver 3 days before delivery, by electron microscopic, biochemical and physicochemical techniques. The ascites hepatoma AH 13 glycogen revealed two major different types of glycogen macromolecules by sucrose discontinuous density gradient centrifugation. The glycogen of the light fraction was very similar to rat muscle glycogen macromolecules in its size and shape except that it exhibited a stronger Cotton effect on measurement of the optical rotatory dispersion and circular dichroism than the muscle glycogen. Furthermore, this light material different from normal muscle glycogen. The other glycogen which also included very small amounts of irregular particles of glycogen macromolecules was contained in the heavy fraction was very similar to the adult rat liver glycogen macromolecules which did not display the Cotton effect. Electron micrographs showing the ultrastructure of the glycogen particles extracted from the AH 13 cells by negative staining revealed a variety of size and shape, and they contained two types of glycogen macromolecules with the smaller muscle types and larger adult type of liver glycogen macromolecules. The glycogen macromolecules also formed varied irregular structures in conformation.