8-Amino-deoxyAdenosine (8-Amino-dA) is an 8-amino-purine that is most commonly used to study the structural and functional properties of triple helices. The 8-amino group is able to form an additional Hoogsteen purine-pyrimidine hydrogen bond, which serves to increase triple helix stability (1). Moreover, it has been shown that triple-helix-forming oligos (TFO) containing 8-amino-dA form stable helices at neutral pH, instead of under acidic conditions (2). This property may be relevant for design of TFOs slated for in vivo work, which generally occurs under physiological pH (7.3-7.4) conditions.
1. Cubero, E., Avino, A., de la Torre, B.G., Frieden, M., Eritja, R., Luque, F.J., Gonzalez, C., Orozco, M. Hoogsteen-based parallel-stranded duplexes of DNA. The effect of 8-amino derivatives. J. Am. Chem. Soc. (2002), 124: 3133-3142.
2. Zhu, Q., Delaney, M.O., Greenberg, M.M. Observation and elimination of N-acetylation of oligonucleotides prepared using fast-protecting phosphoramidites and ultra-mild deprotection. Bioorg. Med. Chem. Lett. (2001), 11: 11105-1107.