| Abstract: | Abstract— Double-stranded DNA, after u.v. irradiation, was degraded by the action of deoxy-ribonuclease and snake venom phosphodiesterase. In addition to mononucleotides a number of nuclease-resistant oligonucleotides, containing photochemically altered bases, could be detected and separated by column chromatography. The phosphorus contents indicated the existence of some photoproducts other than dimers of pyrimidines, especially within the trinucleotide fraction. Comparison of the DNase action on irradiated and on unirradiated DNA suggests that DNase is hindered from splitting the chain next to a photoproduct, tetra-nucleotides being the smallest and octanucleotides the most frequent degradation products bearing an altered base. |
