Stabilizing Effect of Ribonuclease Inhibitor on Structure of Polysomes and Some Properties of Four Classes of Ribosomal Particles in Rat Liver Cytoplasm***

Abstract

The RNase released from the liver microsomes by the DOC-treatment, degraded the polysomal structure. The RNase inhibitor, prepared from the 105, 000 × g supernatant of the liver depressed this RNase activity and prevented the polysomal breakdown. The polysomes and 75S+110S ribosomes present in the free and bound states, respectively, were isolated from rat liver by employing the RNase inhibitor, and their proportion in the cytoplasm, sedimentation behaviors, and incorporating activities were compared. It was found that the addition of RNase inhibitor during the preparation enhanced the reproducibility in regard to high yield, good sedimentation pattern, and high incorporating activity in each polysomal preparation. The incorporating activity of free polysomes was somewhat higher than that of bound polysomes, and that of 75S+110S ribosomes in free and bound states were very low, as compared with that of polysomal preparations.