[Preparatory extraction of 5'-oligoribonucleotides using ribonuclease from cobra venom]

Cobra (Naja oxiana) venom ribonuclease, which catalyses hydrolysis of polyribonucleotides to 5'-oligonucleotides, was used to obtain preparatively isoplit oligonucleotide fractions, containing 2-30 nucleotides. The yield of hydrolysis products varied depending on the degree of hydrolysis. Hydrolysis rates of different polynucleotides were studied. Hydrolysis rate of polyadenylic acid was 20 times as high as that for polyuridylic acid. Quantitative ratios of isoplit fractions did not vary significantly under similar degree of hydrolysis of polyadenylic and polyuridilic acids. Chromatography on QAE-Sepahdex in ammonium bicarbonate concentration gradient containing 15% dioxan was used to separate enzymatic hydrolysates of polynucleotides, which permitted to bring the fraction isolation to simple evaporation.