IN-VITRO PROTEIN-FOLDING BY RIBOSOMES FROM ESCHERICHIA-COLI, WHEAT-GERM AND RAT-LIVER - THE ROLE OF THE 50S PARTICLE AND ITS 23S RIBOSOMAL-RNA

Ribosomes from a number of prokaryotic and eukaryotic sources (e.g., E scherichia coil, wheat germ and rat liver) can refold a number of enzy mes which are denatured with guanidine/HCl prior to incubation with ri bosomes. In this report, we present our observations on the refolding of denatured lactate dehydrogenase from rabbit muscle and glucose-6-ph osphate dehydrogenase from baker's yeast by ribosomes from E. coli, wh eat germ and rat liver. The protein-folding acivity of E. coli ribosom es was found to be present in 50S particles and in 23S rRNA. The 30S p article or 16S rRNA did not show any protein-folding activity. The pro tein-folding activity of 23S rRNA may depend on its tertiary conformat ion. Loss of tertiary structure, by incubation with low concentrations of EDTA, inhibited the protein-folding activity of 23S rRNA. This low concentration of EDTA had no effect on folding of the denatured enzym es by themselves.