pH-independent inhibition of restriction endonuclease cleavage via triple helix formation by oligonucleotides containing 8-oxo-2'-deoxyadenosine.

The ability of homopyrimidine oligonucleotides containing 8-oxo-2'-deoxyadenosine to form stable, triple helical structures with the sequence containing the recognition site for the class II-S restriction enzyme, Ksp632-I, was studied as a function of pH. The 8-oxo-2'-deoxyadenosine-substituted oligomers were shown to inhibit enzymatic cleavage and to bind within the physiological pH range in a pH-independent fashion without compromising specificity.