PHYSICAL AND BIOCHEMICAL STUDIES ON THE MICROSOMES AND RIBOSOMES
Abstract
Ultracentrifugal analysis of ribosomes has revealed that ribosomes extracted from guinea pig liver were dissociated through two intermediate components with 50 S and 60 S to a final stage, in which the large (47 S) and the small (32 S) subunit exist in a weight ratio of 2:1, similar to the E. coli ribosomes. From the molecular weight determination, it was suggested that, in the intermediate stage, the small subunit probably exists as a dimer, thus overlapping the sedimentation peak of the large subunit. Sedimentation analysis either by ultracentrifugation or by sucrose density gradient centrifugation has shown that the 50 S and the 60 S components are both composed of the large and the small subunit. It was found that the small subunit is released from the 50 S and 60 S component in the solution containing less than 1 - 2.5 x 10-5 M Mg ion, while in the solution containing more Mg ion, no such release was observed. The small and the large subunit were isolated in the presence of Mg and the association between the same and the different kind of ribosomal subunit was examined. These components, which were isolated by the sucrose density centrifugation, were observed by an electronmicroscope using shadow casting method. All the particles were spherical except the small subunit which appeared as a flattened disc. The observed diameters of these particles were clearly larger than those for the unhydrated spherical molecules calculated from their molecular weights but were smaller than those of hydrodynamically equivalent spheres calculated from the molecular weight and sedimentation coefficient.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 06, 1965
- Accession Number
- AD0480167
Entities
People
- Akira Inouye
Organizations
- Kyoto University