2 '-O,4 '-C-methylene bridged nucleic acid (2 ',4 '-BNA): Synthesis and triplex-forming properties

For development of ideal antisense and antigene molecules, various chemical modifications of oligonucleotides have been studied. However, despite thei r importance. there is only limited information available on the tripler-fo rming ability of the conformationally restricted or locked oligonucleotides . We report herein that 2'-O,4'-C-methylene bridged nucleic acid (2',4'-BNA ) modification of tripler-forming oligonucleotide: (TFO) significantly enha nces the binding affinity towards target dsDNA. On T, measurements. the tri plex with the 2',4'-BNA oligonucleotides were found to be stabilized with D eltaT(m)/modification of +4.3 to + 5 degreesC at pH 6.6 compared to the tri plexes with the unmodified oligonucleotide. By means of gel-retardation ass ay, the binding constant of the 2'.4'-BNA oligonucleotide at pH 7.0 was at least 300-fold higher than that of the natural oligonucleotide. In addition , the 2',4'-BNA oligonucleotide clearly showed the inhibition of the NF-K-B transcription factor (p50)-target dsDNA binding by forming a stable triple r at pH 7.0. (C) 2001 Elsevier Science Ltd. All rights reserved.