Incorporation of α- and β-LNA (Locked nucleic acid) monomers in oligodeoxynucleotides with polarity reversals

The thymidine monomers of LNA with both α- and β-configuration are incorporated with polarity reversals (i.e., with 3′–3′ and 5′–5′ junctions) in oligodeoxynucleotides with β- and α-configuration, respectively. A 5′-O-phosphoramidite of the β-LNA monomer is synthesised. Large destabilisations of duplexes with both complementary DNA and RNA are observed for oligodeoxynucleotides containing the α-LNA monomer, whereas a duplex with complementary RNA of an α-oligodeoxynucleotide containing the β-LNA monomer is not destabilised.