Structure of the DNA of bacteriophage φX174. VII. Methylation

The only methylated base present in φX174 DNA has been found to be 5-methylcytosine. The number of methyl residues per molecule of φX DNA is estimated to be not more than one. This 5-methylcytosine appears in the φX174 DNA in a non-random distribution; it is found almost exclusively in the dinucleotide fraction of the pyrimidine isopliths, and as judged by its electrophoretic characteristics, the sequence of the 5-methylcytosine containing dinucleotide is either p-m^5C-p-T-p or p-T-p-m^5C-p