Photooxidation of oligodeoxynucleotides by UO2(2+).

Photooxidation and consequent cleavage of oligodeoxynucleotides by the uranyl ion is greatly enhanced in the presence of a terminal 5'- or 3'-phosphate group. This enhanced cleavage is confined to nearby phosphodiester bonds in the case of a 5'-phosphate, but is less localized in the case of a 3'-phosphate. Several attempts to use a complementary oligodeoxynucleotide to direct a uranyl "warhead" against an oligodeoxynucleotide target were unsuccessful. Our results are most easily explained if we suppose that uranyl ions form coordination complexes with terminal phosphates and that, on photoexcitation, coordinated uranyl ions extract a hydrogen atom from the CH bond of a nearby deoxyribose residue.