On the distribution and packing of RNA and protein ribosomes.

From the analysis of the measured radii of gyration of the RNA (Rg = 6.6 +/- 0.3 nm) and protein (Rg = 10.2 +/- 0.5 nm) components of the 50-S subparticle of Escherichia coli ribosomes it is concluded that proteins containing a large amount of hydrodynamically bound water are located on the periphery of the tightly packed RNA. We found that the common features of the measured X-ray scattering curves of the E. coli 70-S ribosome, its 30-S and 50-S subparticles and wheat 80-S ribosomes in the region of scattering angles corresponding to scattering vectors mu from 1 to 5 nm-1 reflect features of the RNA compact packing. A hypothesis is proposed that the compact packing of RNA helices in the range of Bragg distances of 4.5--2.0 nm is a general structural feature of all ribosomal particles.