Physical characteristics of protein-deficient derived from the 50S ribosomal subunit

Sedimentation coefficients, diffusion coefficients, density increments, extinction coefficients, and molecular weights were determined for selected core particles from the 50S Escherichia coli ribosomal subunits. These core particles were found to be loosened structures containing less than half the protein present on the intact 50S subunits and totally lacking peptidyl transferase and polyphenylalanine synthesis activity unless reconstituted. The results of this study confirm that a loosening of the subunit takes place upon the removal of protein, but this loosening is not necessarily due to the loss of the protein.