Nucleosides and Nucleotides. 153. Effects of 2′-α- and 2′-β-Bromo-2′-deoxyadenosine on Oligonucleotide Hybridization and Nuclease Stability

1-(2-Bromo-2-deoxy-β- -ribofuranosyl)adenine (1) and 1-(2-bromo-2-deoxy-β- -arabinofuranosyl)adenine (2) were incorporated into DNA pentadecamers. The oligonucleotides containing 1 destabilized DNA/DNA and DNA/RNA duplex formation. However, the oligonucleotides containing 2 slightly stabilized DNA/DNA duplex formation, although they decreased the stability of DNA/RNA duplexes. Furthermore, the oligonucleotide containing 2 was more resistant to snake venom phosphodiesterase than an unmodified oligonucleotide (dA)15 and the oligonucleotide containing 1.