Nucleotide Clusters in Deoxyribonucleic Acids. VIII. The Pyrimidine Oligonucleotides of Bacteriophage S13 Wild Type DNA
A method for determination of the compositional assignment and comparison of the oligonucleotides in longer pyrimidine isostichs from closely related DNA's is described. The method is a dual 32P/33P labelling technique and has been used to investigate the pyrimidine oligonucleotide catalogue of bacteriophage S13 wild type DNA by comparison with the catalogue of the nitrous acid amber mutant S135suN15. The isomeric compositions of the dinucleotide CTp3 and trinucleotides CT2p4 and C2Tp4 from both DNA's were examined also. No cytosine (C) → thymine (T) transitions had occurred in the longer pyrimidine isostichs 7–11 inclusive, which constitute 10% of the catalogue of each of the two S13 DNA's, the catalogues of the two DNA's being indistinguishable.