Isolation and anaylsis of (Gp)nXp sequences of rat liver 5S RNA by means of restricted ribonucleas T2 hydrolysis.

Essentual difficulties arise when base number in oligoguanylic blocks and location of these blocks along the polynucleotide chain need to be determined in the course of determination of the nucleotide sequences in ribonucleic acids. To overcome this difficulty it is suggested to take advantage of a recently discovered resistance of phosphodiester bond between kethoxalated G and its 3'-neighbour against T(2) RNase hydrolysis 1,2. The approach is illustrated by analysis of 5S RNA from rat liver. Sequences of general formula (Gp)(n)Xp were isolated from T(2) RNase hydrolysate of 5 S RNA rapidly and quantitatively. The information obtained greatly facilitates the whole procedure of sequencing. It is expected that the method proposed would be effective for analysis of 5 S and 4 S RNA and for highmolecular weight fragments of ribosomal and viral RNAs.