Preparative isolation of mono-, di- and tripurine nucleotides from hydrolysates of depyrimidinated herring sperm DNA

The purine nucleotides pdAp, pdGp, (dA)2, (dA-dG), (dG-dA), (dG)2, (dA)3, (dA-dG-dA), (dA-dA-dG), (dG-dA-dA), (dG-dA-dG) and known mixtures of purine nucleotide sequence isomers were separated by preparative scale chromatography of partial hydrolysates of depyrimidinated herring sperm DNA. Herring sperm DNA is first partially hydrolysed to a mixture of purine nucleotides. The low-molecular-weight oligonucleotides are then separated by column chromatography on DEAE-cellulose at pH 7.5, and fractionated by chromatography on QAE-Sephadex. Impurities which are not fully removed by column chromatography are separated by paper chromatography. The sequence of the isolated DNA fragments and the composition of the mixtures of sequence isomers were determined from the chromatographic data, absorption characteristics and by enzymatic degradation.