[Mesophase state of double-stranded RNA and polyribonucleotides characterized by high optical activity]

A small-angle reflexion in X-rayograms and an intense band at A approximately 270 nm in the CD spectrum are assigned to compact particles that arise when mixing water-salt solutions of PEG with water-salt solutions of double-stranded RNA and those of poly(A) poly(U) and poly(I) poly(C). The discrepancy between the 35-40 A small-angle and the approximately 20 A small-angle reflexion typical for double-stranded poly-nucleotide crystals together with the presence of the intense band in the CD spectra point out to the fact that the double-stranded RNA molecules and the molecules of polyribonucleotides exist in a mesophase (liquid crystalline) state. The compact particles of double-stranded RNA and those of polyribonucleotides are shown to be able to have either a positive or a negative band of the CD spectrum depending on PEG concentration, ionic strength or temperature of the solution.