Pyrazolo[3,4-d]pyrimidine Nucleic Acids: Adjustment of the dA-dT to the dG-dC Base Pair Stability

Abstract

The pyrazolo[3,4-d]pyrimidine-4,6-diamine nucleosides 2b-d stabilize the dA-dT base pair significantly when the dA-residue is replaced. Oligonucleotide duplexes incorporating 2b-d show a 4–6°C T m increase per modification. The 7-bromo compound 2b harmonizes the stability of the dA-dT vs. the dG-dC pair. According to this the stability of such duplexes depends no longer on the base pair composition of a DNA molecule.