In a previous publication, we presented predictions for the secondary structure of eleven proteins from the small subunit of the Esckerickia coZi ribosome [ 1 ] . The present work is an extension of these studies to the proteins deriving from the 50 S subunit. Predictive methods offer a means of assigning regions of highly probable conformation to proteins of known primary structure. The results can be related to other findings on the topography of the ribosomal subunits. Such an approach is valuable at a time when X-ray analyses of these proteins are not available. The predictions provide guidelines to the secondary structures of the proteins for directed studies of protein-protein neighbourhoods and the interactions of the proteins with the strands of ribosomal RNA. For this purpose we applied four different predictive methods and, using the known amino acid sequences of these proteins, the calculated secondary structures were presented as diagrams showing the expected conformational states of each residue, i.e. for helix, extended structure, turn and random coil. Regions of highly probable secondary structure were derived from these histograms when at least three predictive methods agree about the conformational state of a residue [2].
