DISSOCIATION OF OXIDIZED 80-S RIBOSOMES BY SODIUM DEOXYCHOLATE

1. 80-S Ribosomes obtained from brine-shrimp gastrulae, sea-urchin eggs, and yeast were readily dissociated into two major subunits by sequential treatment with millimolar quantities of NaOCl or H2O2, and 0.5% sodium deoxycholate. 2. The ability of deoxycholate to dissociate NaOCl-treated ribosomes was shared by two other anionic detergents, sodium dodecyl sulfate and sodium dodecyl sarcosinate. Several nonionic detergents were tested but none produced dissociations. Anionic deoxycholate analogues, sodium cholate for example, were likewise ineffective. 3. The extent of ribosome dissociation produced by deoxycholate was a function of the concentration of NaOCl and deoxycholate used, and the temperature and duration of incubation. Although elevated Mg2+ concentrations prevented dissociation, the effect of the detergent could not be attributed simply to the removal of bulk Mg2+ from the incubation medium. 4. Treatment of ribosomes with NaOCl alone did not alter their ultraviolet-absorption spectra, density gradient sedimentation profiles, or RNA and protein content when compared with controls, indicating that major changes in ribosome composition were not produced by the oxidizing agent. However, poly U-directed phenylalanine incorporation by 80-S ribosomes was greatly reduced after NaOCl treatment, suggesting that groups on the ribosome associated with poly U attachment or function were among those affected by the oxidation. 5. Polyribosomes and loaded" monosomes were not degraded by NaOCl-deoxycholate treatment. © 1969."