Intercalating nucleic acids (INAs) with insertion of N-(pyren-1-ylmethyl)-(3R,4R)-4-(hydroxymethyl)pyrrolidin-3-ol.: DNA (RNA) duplex and DNA three-way junction stabilities

N-(Pyren-1-ylmethyl)-(3R,4R)-4-(hydroxymethyl)pyrrolidin-3-oI was synthesised from (3R,4R)-4(hydroxymethyl)pyrrolidin-3-ol and (3R,4S)-4-[(IS)-1,2-dihydroxyethyl]pyrrolidin-3-ol using alkylation with 1-(chloromethyl)pyrene or reductive amination with pyrene-1-carbaldehyde and NaCNBH3. The incorporation of N-(pyren- 1-ylmethyl)azasugar moiety into oligodeoxynucleotides (ODN) as a bulge to form an intercalating nucleic acid (INA) induced a slight destabilization of INA-DNA duplex, whereas the INA-RNA duplex was strongly destabilized and 9 degreesC difference per modification in thermal stability between INA-DNA over INA-RNA duplexes was observed. The stabilization of a DNA three way junction (TWJ) was improved when the intercalator moiety was inserted into the junction region as a bulge.