A spectrophotometric study of the secondary structure of ribonucleic acid isolated from the smaller and larger ribosomal subparticles of rabbit reticulocytes.

The spectrum of RNA from the smaller and larger subparticles of rabbit reticulocyte ribosomes was studied as a function of pH, ionic strength, urea concentration and temperature. It was inferred that both RNA species form short double-helical segments of not more than about 10 base-pairs in length. Not more than about 70% of the base residues may be located in double-helical segments. RNA from the larger subparticle is richer in guanine and cytosine residues and its secondary structure is the more stable. These conclusions are based on the use of double-helical RNA from virus-like particles and of unfractionated Escherichia coli tRNA as model systems.