THE ISOLATION, CHARACTERIZATION AND ACID-BASE PROPERTIES OF RIBONUCLEIC ACID FROM RABBIT-RETICULOCYTE RIBOSOMES

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Abstract
RNA was isolated from rabbit-reticulo-cyte ribosomes in better than 90% yield by precipitation as the guani-dinium salt. After precipitation of the RNA, ribosomal protein was recovered from the guanidinium chloride solution by dialysis. Ribosomal RNA was found to be an approximately equimolar mixture of two species having sedimentation coefficients, S20, w, of 16.8''s and 29.8''s. The quality of the RNA, as judged by the proportion of the faster-sedi-menting component and the sharpness of the boundaries, compared favourably with that of RNA isolated by extraction with aqueous phenol or sodium lauryl sulphate. The sedimentation pattern of RNA did not depend on the extent to which the ribosome preparations function in the incorporation of labelled amino acids into peptide linkage, but pretreat-ment of ribosomes with ribonuclease led to polydisperse preparations of RNA. Reticulocyte RNA was titrated electrometrically and spectro-photometrically. The results were consistent with the formation in neutral salt solutions of a stable secondary structure which was determined by a non-random nucleotide sequence.