Photochemical cleavage of single- and double-stranded oligonucleotides by 3-(p-tolylamino)-1,5-azulenequinone

Irradiation, with 350 nm UV light, of specially designed and synthesized single- and double-stranded oligodeoxyribonucleotides in the presence of 3-(p-tolylamino)-1,5-azulenequinone produced fragments resulting from the cleavage at the deoxyguanosine residue only. The cleaving efficiency was greater for a single strand than a double helix. The efficiency was increased for a less stable double helix, or while the deoxyguanosine residue therein was located at a bulge, at a hairpin loop, or towards the end of the helix.