LNA units present in [R-P-PS]-(DNALNA) chimeras enhance the thermal stability of parallel duplexes and triplexes formed with (2 '-OMe)-RNA strands

摘要

The results of CD measurements indicate that 2-4 LNA units distributed along 12 nt P-stereodefined phosphorothioate[R-P-PS]-(DNALNA)chimeras impose a C3 '-endoconformation on the 2 '-deoxyribonucleosides. Under neutral and slightly acidic conditions homopurine[R-p-PS]-(DNALNA) hybridizes with 9-12 nt Hoogsteen-paired (2 '-OMe)-RNA strands to form parallel duplexes, which are thermally more stable than the reported earlier analogous complexes containing LNA-free [R-P-PS]-DNA oligomers (Delta T-m= 7 degrees C per LNA unit at pH 5.4). Upon addition of the corresponding Watson-Crick-paired (2 '-OMe)-RNA strands, parallel triplexes are formed with further increased thermal stability.