Mapping of deoxydi- and trinucleotides liberated by the action of endonucleases from the silkworm and Aspergillus oryzae

Abstract

Both silkworm nuclease and nuclease O of Aspergillus oryzae mycelia hydrolyse DNA endolytically to di- and trinucleotides terminating in 5′-phosphate. These oligonucleotides were fractionated first by DEAE-cellulose chromatography with 7 M urea into the respective isoplithic groups and then analysed for the composition and isomerism: each group was labeled 5′-terminally by the [γ- 32P]ATP-polynucleotide kinase reaction and then electrophoresed monodimensionally for the dinucleotides and two-dimensionally for the di- and trinucleotides mixtures, respectively, followed by elution and digestion with snake venom exonuclease. Both nucleases gave rather similar simple maps in which all sixteen dinucleotides and almost all the possible trinucleotides were identified, indicating their random mode of actions.