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

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Abstract
Proteins L1, L9, L25 and L30, purified by a nondenaturing method from the 50S ribosomal subunit of E. coli A19, were characterized. The 4 proteins were studied under conditions which resemble those used for reconstitution experiments. These proteins have so20,w [sedimentation coefficient at 20.degree. C in water] values of 2.0 S, 1.8 S, 1.8 S and 1.0 S and D202 [diffusion coefficient at 20.degree. C in water] values of 8.4 .times. 10-7, 9.0 .times. 10-7, 14.0 .times. 10-7 and 15.0 .times. 10-7 cm2/s. Apparent specific volumes at 20.degree. C are 0.738, 0.733, 0.700 and 0.735 ml/g for the 4 proteins. The respective MW determined by sedimentation equilibrium are 25,000, 17,300, 12,000 and 6500. The intrinsic viscosity values for the 4 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.