Shapes of proteins L1, L9, L25, and L30 from the 50S subunit of the Escherichia coli ribosome, determined by hydrodynamic studies.

Proteins L1, L9, L25, and L30, purified by a nondenaturing method from the 50S ribosomal subunit of Escherichia coli A19, have been characterized. The four proteins were studied under conditions which resemble those used for reconstitution experiments. These proteins have S020,W values of 2.0 S, 1.8 S, 1.8 S, and 1.0 S and D20,W values of 8.4 X 10(-7), 9.0 X 10(-7), 14.0 X 10(-7), and 15.0 X 10(-7) cm2/S. Apparent specific volumes at 20 degrees C are 0.738, 0.733, 0.700, and 0.735 mL/g for the four proteins. The respective molecular weights determined by sedimentation equilibrium are 25 000, 17 300, 12 000, and 6500. The intrinsic viscosity values for the four proteins are 4.0, 5.5, 3.6, and 3.2 mL/g. From these hydrodynamic parameters L1 and L9 appear to have globular or at most only slightly elongated shapes, whereas L25 and L30 appear to be definitely globular.