Pressure-jump relaxation studies of the association--dissociation reaction of E. coli ribosomes.

The association--dissociation kinetics of ribosomal particles from E. coli have been studied using a pressure-jump apparatus with optical detection. Experiments on isolated subunits yield two relaxation times of about 10 and 700 ms, respectively. With mixtures of 30 S and 50 S particles an additional relaxation time of about 100 ms is observed, which is assigned to the equilibrium 30 S + 50 S in equilibrium 70 S. The two other times are attributed to reversible equilibria between subunit monomers and subunit homo-associates.