Studies on human glycogen. II. Sedimentation in the ultracentrifuge.

Early investigations of the size of glycogen by osmotic pressure measurements indicated molecular weights of 500,000 to 3,500,OOO for this substance (1, 2). Since that time several studies of glycogen have been made in the ultracentrifuge. Bridgman (3) reported that rabbit liver glycogen is inhomogeneous .with the maximum component, having a sedimentation constant of about 70 S and exhibiting a spread of values from 20 to 120 S. Similar findings were reported by Bell et al. (4) for glycogen samples of different origin. Chargaff and Moore (5) reported the isolation from tubercle bacilli of a glycogen which had an average particle size somewhat greater than those obtained from animal tissues. In the present study, the objective was a comparison of glycogen samples from normal individuals and from those having glycogen disorders. All the samples mere purified in the same manner in order to obtain comparative results (0) since it is recognized that different methods of handling may be reflected in the physical properties of the glycogen. A single sample of glycogen from normal human muscle studied by Bell et al. (4) did not differ significantly from the animal preparations. In the present investigation it was found that glycogen from a patient (N. D.) with a glycogen storage disorder of muscle’ differed from normal samples in the distribution of scdimenting components. Preparations of human liver glycogen show two distinct sedimenting peaks, indicating that the distribution of particle sizes is not continuous. These two kinds of liver glycogen have been separated by chemical fractionation and by differential centrifugation in the preparative ultracentrifuge. The glycogen from a single case of liver glycogen storage disease (von Gicrke’s discasc) did not show the hmvy material found in preparations from normal individuals.