PHYSICAL STUDIES ON PROTEIN-L3 AND PROTEIN-L24 FROM THE 50-S SUBUNIT OF THE ESCHERICHIA-COLI RIBOSOME

Proteins L3 and L24, purified by a nondenaturing method from the 50 S ribosomal subunit of Escherichia coli A19, have been characterized. Both proteins were studied under conditions which resemble those used for reconstitution experiments. They were soluble at approximately 2-3 mg/ml and showed little or no aggregation. These proteins have s0 20,w values of 2.0 and 1.5 S, and D20,w values of 7.6 × 10-7 and 11.0 × 10-7 cm2 s-1. Partial specific volumes at 20 °C are 0.730 and 0.740 ml g-1 for the two proteins. The respective molecular weights determined by sedimentation equilibrium are 24,500 and 12,000. The intrinsic viscosity values for the two proteins are 6.0 and 4.0 ml g-1. From these hydrodynamic parameters an elongated shape for L3 and a globular shape for L24 have been inferred. © 1979.