OLIGONUCLEOTIDE-POLYAMIDE HYBRID MOLECULES CONTAINING MULTIPLE PYRENERESIDUES EXHIBIT SIGNIFICANT EXCIMER FLUORESCENCE

Oligonucleotide-polyamide hybrid molecules bearing multiple pyrene res idues in the polyamide moiety were prepared. These molecules were desi gned to promote pyrene excimer formation and avoid intercalation of th e label into the DNA duplex. Significant excimer fluorescence was obse rved, and this was shown to increase with the number of pyrene residue s present. Hence, there is potential for further increasing of the flu orescence intensity by incorporation of additional label residues. Exc imer fluorescence intensity was also shown to be sensitive to duplex f ormation. Fluorescence measurements and melting temperature studies ga ve no evidence of intercalation of the pyrene residues into duplex DNA . The hybridization properties of these hybrid molecules are similar t o those of unmodified oligonucleotides. It seems, then, likely that py renylated oligonucleotide-polyamide hybrids may be useful as oligonucl eotide probes.