[Oligo(2'-O-methylribonucleotides) and their derivatives: III. 5'-mono- and 5'-bispyrenyl derivatives of oligo(2'-O-methylribonucleotides) and their 3'-modified analogues: synthesis and properties].

5'-Pyrenylmethylphosphoramidite and 5'-bispyrenylmethylphosphordiamidite derivatives of oligo(2'-O-methylribonucleotides) and their analogues with thymidine attached at their 3'-termini by a 3'-3'-phosphodiester internucleotide bond (inverted thymidine) were synthesized. The effect of the pyrene residue(s) on the thermal stability of duplexes of the modified oligonucleotides with RNA and DNA was studied. A possibility of detection of hybridization of 5'-mono- and 5'-bispyrenyl derivatives with RNA and DNA targets in solution was demonstrated according to the changes in fluorescence. 5'-Pyrenylmethylphosphoramidite derivatives of oligo(2'-O-methylribonucleotides) and their inverted analogues were shown to serve as sensitive probes for the detection of oligonucleotide substitutions in RNA and DNA by the method of thermal denaturation of the formed duplexes detected according to changes in their fluorescence.