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Cover Picture: Forced Intercalation Probes (FIT Probes): Thiazole Orange as a Fluorescent Base in Peptide Nucleic Acids for Homogeneous Single-Nucleotide-Polymorphism Detection (ChemBioChem 1/2005)
The cover picture shows new PNA probes–FIT Probes–and their use in homogenous DNA detection and was designed by Elke Socher. In FIT Probes, the thiazole orange dye is forced to intercalate at a specific position of a probe–target complex. In their paper on p. 69 ff, O. Seitz et al. describe how the binding of FIT probes with DNA results in fluorescence enhancements due to the coplanarization of the two heterocyclic ring systems. The remarkable attenuation of fluorescence that is observed when forcing thiazole orange to intercalate next to a mismatched base pair allows a DNA target to be distinguished from its single-base mutant under nonstringent hybridization conditions, a property that should be of advantage for real-time quantitative PCR and nucleic acid detection within living cells.