RIBOSOMAL SUBUNITS IN DICTYOSTELIUM DISCOIDEUM EFFECT OF AN IONIC DETERGENT AND A NONIONIC DETERGENT

The effect of the anionic detergent, sodium deoxycholate, and of the nonionic detergent, Nonidet P 40, on the ribosomes of the slime mold Dictyostelium purpureum have been studied. Lysis of log- or stationary-phase cells with Nonidet did not reveal any ribosomal subunits. However, when deoxycholate was used all the ribosomes were in the form of subunits. By increasing the Mg2+ concentration and/or by lowering that of the deoxycholate, it has been possible to preserve the intact ribosomes. It is conduced that in D. purpureum, the ribosomes are not in the form of subunits or that the number of subunits is too small to be seen as absorbances. These results are discussed in the light of recent events, which suggest that ribosomes must dissociate for polypeptide chain initiation. © 1969.