Site-specific RNA cleavage using terpyrtdine center dot Cu(II)-linked 2 '-O-methyloligonucleotides

2'-Deoxy- and 2'-O-methyl-5'-O-terpyridyl derivatives of adenosine and cyti dine were synthesized and used to construct 5'-end-modified oligonucleotide s. These antisense agents complexed with Cu(II) exclusively cleaved a compl ementary RNA oligomer at the site opposite the terpyridine-nucleoside resid ue. We also found that the terpyridine . Cu(II) moiety stabilizes 2'-O-meth yl RNA duplex. These suggest that after RNA hybridization, the terpyridine moiety is close to the RNA strand, presumably in an end capping manner.