[Preparative isolation of tri-, tetra-, penta- and hexapyrimidine nucleotides from hydrolysates of depurinated herring sperm DNA (author's transl)].

The pyrimidine nucleotides p(dC)3p, p(dT)3p and p(dT)4p and mixtures of the sequence isomers p(dC3, dT), (dC3, dT)p; p(dC3, dT)p; p(dC2, dT2)p; p(dC, dT3)p; p(dC3, dT2)p; p(dC2, dT3); p(dC2, dT3)p; p(dC, dT4)p; p(dC4, dT2); p(dC3, dT3); p(dC3, dT3)p and p(dC2, dT4)p have been isolated on a preparative scale from hydrolysates of depurinated herring sperm DNA. The DNA hydrolysate is first separated into a high- and a low-molecular weight pyrimidine nucleotide mixture by column chromatography at pH 7.5 on DEAE-cellulose. The high-molecular-weight pyrimidine nucleotide mixture is further separated into four peaks on QAE-Sephadex at pH 7.5. The second peak is re-chromatographed on QAE-Sephadex at pH 3.5. Pyrimidine nucleotides containing predominantly cytidylic acid units may thus be separated from these with predominantly thymidylic acid units. Subsequent separation according to number of phosphate groups at pH 7.5 on QAE-Sephadex yields products of 70--93% purity. In a final separation step, the pyrimidine nucleotides and mixtures of sequence isomers are once again chromatographed on QAE-Sephadex with 7 M urea at pH 7.5. The products thus obtained are generally chromatographically pure. Impurities which are not fully removed by column chromatography are separated by paper chromatography. The structure of the isolated DNA fragments and the composition of the mixtures of sequence isomers are determined from the chromatographic data, absorption characteristics and by enzymatic degradation.