Synthesis and Biophysical Investigations of Oligonucleotides Containing Galactose-Modified DNA, LNA, and 2′-Amino-LNA Monomers

Galactose-modified thymidine, LNA-T, and 2′-amino-LNA-T nucleosides were synthesized, converted into the corresponding phosphoramidite derivatives and introduced into short oligonucleotides. Compared to the unmodified control strands, the galactose-modified oligonucleotides in general, and the N2′-functionalized 2′-amino-LNA derivatives in particular, showed improved duplex thermal stability against DNA and RNA complements and increased ability to discriminate mismatches. In addition, the 2′-amino-LNA-T derivatives induced remarkable 3′-exonuclease resistance. These results were further investigated using molecular modeling studies.