Abstract
The P-N bond in oligonucleotide P3′ → N5′ phosphoramidates (5′ -amino-DNA) is known to be chemoselectively cleaved under mild acidic conditions. We prepared homopyrimidine oligonucleotides containing 5′ -amino-5′ -deoxythymidine (5′ -amino-DNA thymine monomer) or its conformationally locked congener, 5′ -amino-2′,4′ -BNA thymine monomer, at midpoint of the sequence. The effect of triplex formation with homopurineohomopyrimidine dsDNA targets on acid-mediated hydrolysis of the P3′ → N5′ phosphoramidate linkage was evaluated. Very interestingly, it was found that the triplex formation significantly accelerates the P-N bond cleavage.