Conjugation of various acridines to DNA for site-selective RNA scission by lanthanide ion.

Three types of DNA conjugates having 9-acridinecarboxamide, 9-aminoacridine, and 9-amino-6-chloro-2-methoxyacridine at the 5'-ends were synthesized and used for site-selective RNA scission together with another unmodified DNA and Lu(III) ion. The target phosphodiester linkages in the substrate RNA were selectively and efficiently activated and were hydrolyzed by free Lu(III) ion. The conjugate bearing 9-amino-6-chloro-2-methoxyacridine was the most active. However, its duplex with the substrate RNA was almost as stable as that of the 9-aminoacridine-bearing conjugate, which was much less active for the RNA activation. The 9-acridinecarboxamide-bearing conjugate was only marginally active. The substituents on the acridine groups in these conjugates positively participate in the present RNA activation, probably by fixing the orientation of the acridine rings.