Synthesis and Properties of Oligonucleotides Containing 3′-O,4′-C-Ethyleneoxy-Bridged 5-Methyluridines

Abstract

-A phosphoramidite of 3ʹ-O,4ʹ-C-ethyleneoxy-bridged 5-methyluridine (3ʹ,4ʹ-EoNA-T) was successfully incorporated into oligonucleotides, and their abilities to form duplexes with RNA and DNA as well as triplexes with double-stranded DNA were evaluated. The stabilities of the duplexes formed between RNA and 3ʹ,4ʹ-EoNA-modified oligonucleotides were only slightly lower than those of the natural DNA-RNA duplex, while the duplexes formed between 3ʹ,4ʹ-EoNA-modified oligonucleotides and DNA were drastically less stable than the natural DNA-DNA duplex. Moreover, under the same conditions as the UV-melting experiments of the duplexes, 3ʹ,4ʹ-EoNA-modified oligonucleotides were unable to form triplexes with dsDNA. These results showed that oligonucleotides containing 3ʹ,4ʹ-EoNA-T had excellent RNA selectivity.

Synthesis, Duplex-Forming Ability, and Enzymatic Stability of Oligonucleotides Modified with Amide-Linked Dinucleotides Containing a 3′,4′-Tetrahydropyran-Bridged Nucleic Acid

“…We have previously developed several 3′,4′-bridged nucleic acids (3′,4′-BNAs, Figure ). − The sugar conformation of all 3′,4′-BNAs and trans -3′,4′-BNAs is an S-type. Shaikh et al developed a bicyclic 2′-deoxyribonucleoside with a 3′,4′-bridge structure, and X-ray crystal structural analysis revealed that the sugar conformation of the nucleoside was, interestingly, an N-type .…”