[New substances with high specific activity for nucleic acid sequences: oligodeoxynucleotides covalently linked to an intercalating agent].

New molecules are described in which an intercalating agent is covalently linked through a polymethylene chain to an oligodeoxynucleotide. Using an oligodT sequence covalently linked to an acridine dye, it is shown that these molecules bind in a specific way to their complementary sequence (poly (A] and that the stability is strongly enhanced by the intercalating agent as compared with the unmodified oligodT. Substitution of a phosphate group by a positively charged group strengthens complex formation and protects the neighboring phosphodiester bond against nuclease cleavage.