Theoretical calculations, synthesis and base pairing properties of oligonucleotides containing 8-amino-2 '-deoxyadenosine

Theoretical calculations on double and triple helices containing 8-amino-2' -deoxyadenosine were made to analyze the possible differences in base pairi ng properties between 8-aminoadenine and adenine. These calculations indica te a strong preferential stabilization of the tripler over the duplex when adenine is replaced by 8-aminoadenine. In addition, a protected phosphorami dite derivative of 8-amino-2'-deoxyadenosine was prepared for the introduct ion of 8-aminoadenine into synthetic oligonucleotides using the phosphite-t riester approach. DNA triple helical structures are normally observed at ac idic pH. However, when oligonucleotides carrying 8-aminoadenine are used, v ery stable triple helical structures can be observed even at neutral pH, Bi ological applications of triple helices could benefit from the use of 8-ami noadenine derivatives.