Control of folding and binding of oligonucleotides by use of a nonnucleotide linker

A linker containing a terephthalamide group, -P(O)(O - )O(CH 2 ) 6 NHC(O)C 6 H 4 C(O)NH(CH 2 ) 6 OP(O)(O - )-, is shown to be an effective structural element for organizing oligonucleotide chains in solution. Capping a pair of complementary oligonucleotides with this linker leads to marked enhancement in stability of the Watson-Crick duplex structure. Joining a pair of thymidylate oligomers with this linker gives a compound exhibiting unusually high affinity for oligo(dA) strands; even a tetramer unit can be recognized in dilute solution