Cleavage at 5-methylcytosine in DNA by photosensitized oxidation with 2-methyl-1,4-naphthoquinone tethered oligodeoxynucleotides

Photosensitized one-electron oxidation of 5-methylcytosine in DNA by 2-methyl-1,4-naphthoquinone, attached to 5′-end of an oligodeoxynucleotide strand, produced 5-formylcytosine and led to selective DNA strand cleavage at the original 5-methylcytosine configuration. This specified photoreaction is useful for positive display of 5-methylcytosine in DNA on a sequencing gel.