[Antisense oligonucleotides containing 1-(beta-D-2'-deoxy-threo-pentofuranosyl)thymine at the 3'- and 5'-end]

Oligonucleotides with 3'- and 5'-terminal 1-(beta-D-2'-deoxy-threo-pentafuranosyl)thymin residues (inversion at C3'-atom) were obtained by the automatic phosphoramidite synthesis. The modifications protect oligonucleotides from the nuclease degradation and do not affect the stability of nucleic acid duplexes.