ENZYME ACTIVITIES AND ULTRASTRUCTURE OF A MEMBRANE FRACTION FROM HUMAN ERYTHROCYTES

The homogeneity of an isolated membrane fraction of human erythrocytes was studied by density gradient centrifugation in silica solution. A main component (about 90% on a nitrogen basis) was obtained as a single band at a density of 1.08. When analyzed by electron microscopy, this component was found to consist of a membranous structure which, in contrast to isolated ghosts, appeared to be essentially devoid of cytoplasmic structures. The main component, obtained at a density of 1.08 of the gradient, was shown to contain glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase and adenylte kinase. Thus, the present results strongly support the view that part of the glyceraldehyde-3-phosphate dehydrogenase, phophoglycerate kinase and adenylate kinase of the human erythrocyte is intimately associated with the membranous structure. © 1969.