Nucleosides and Nucleotides. 208. Alternate-Strand Triple-Helix Formation by the 3'-3'-Linked Oligodeoxynucleotides with the Anthraquinonyl Group at the Junction Point
The synthesis of 3'-3'-linked oligodeoxynucleotides (ODNs) with the anthraquinonyl group at thejunction point is described. The ODNs were synthesized on a DNA synthesizer using a controlledpore glass (CPG) carrying pentaerythritol that has an intercalator at one of the four hydroxymethylgroups. Stability of the triplexes with the target duplexes was studied by thermal denaturation. The3'-3'-linked ODNs with the anthraquinonyl group enhanced the thermal stability of the triplexes whencompared with those without the intercalator and the unmodified nonamer 10. It was found that theODNs 12 and 13 carrying the anthraquinonyl groups can form thermally stable triplexes by skippingtwo or three extra base pairs between two binding domains of the target duplexes. The ability of the3'-3'-linked ODNs to inhibit cleavage of the target DNA 22 by the restriction enzyme Hind III wastested. It was found that the 3'-3'-linked ODN 16 with the anthraquinonyl group at the junction pointinhibited the cleavage by the enzyme more effectively than the nonamer 14 and the 3'-3'-linked ODN15 without the intercalator.