Oligonucleotide analogues containing the internucleotide linker C3′-NH-CO-CH2-N(CH3)-C5′

Oligonucleotide analogues were synthesized whose internucleoside linker contains an amide bond and a methylamino group (C3'-NH-CO-CH2-N(CH3)-C5'). Melting curves for duplexes formed by modified oligonucleotides and natural oligonucleotides complementary to them were measured, and the melting temperatures and thermodynamic parameters of duplex formation were calculated. The introduction of one modified dinucleoside linker into the oligonucleotide only slightly decreases the melting temperatures of these duplexes compared with unmodified ones. The CD spectra of modified duplexes were studied, and their spatial structures are discussed.