title: Biochemical and biophysical characterization of insulin granules isolated from rat pancreatic islets by an iso-osmotic gradient.
abstract: The size and polydispersity of insulin granules isolated from rat pancreatic islets by centrifugation on a linear iso-osmotic gradient (300 mosM) have been characterized by quasi-elastic light scattering and photon correlation spectroscopy. The separation of granules by the linear gradient technique was compared directly to isolation on discontinuous gradients of hypertonic sucrose (300-1950 mosM) and the greater efficiency of separation assessed by parallel measurements of protein, insulin, cytochrome oxidase and beta-glucuronidase. Granules isolated from pancreatic beta-cells had a mean particle diameter of 342 nm, buoyant density of 1.104, hydrated mass of 23 femtograms and maximal insulin content of 8-9.6 . 10(5) molecules per granule.
mesh_terms: D000818:Animals; D002458:Cell Fractionation; D002499:Centrifugation, Density Gradient / Q000379:methods; D003594:Cytoplasmic Granules / Q000648:ultrastructure*; D007328:Insulin / Q000032:analysis*; D007515:Islets of Langerhans / Q000648:ultrastructure*; D008297:Male; D008854:Microscopy, Electron; D011506:Proteins / Q000032:analysis; D051381:Rats; D013347:Subcellular Fractions / Q000648:ultrastructure
chemical_list: D007328:Insulin; D011506:Proteins