The dissociation of N2 gas-induced monomeric ribosomes from the pea root was studied by varying the concentration of KCI (or NILCI) and MgCL2 in the presence of dithiothreitoL These monoribosomes were shown to dissociate completely into subunits at 0.5 M KCI or NH4CI in the presence of 5 mM MgCI2. The 40S subunits were more susceptible to structural change in KC1 than were the 60S subunits. On the other hand, the 60S subunits appeared to be more labile to NH4CI.The activity of the subunits relative to aminoacyl-tRNA binding and peptide bond formation was investigated using subunits derived from 0.5 M KCI (or NH4CI)