Fluorescence detection of single-nucleotide polymorphism with single-strand triplex-forming DNA probes.

Triple-helix-forming oligonucleotides (TFOs) are widespread in the genome and have been found in regulatory regions, especially in promoter zones and recombination hotspots of DNA. To specifically detect these polypurine sequences, we designed and synthesized two dual pyrene-labeled single-strand oligonucleotide probes (TFO-FPs) consisting of recognition, linker, and detection sequences. The hybridization processes of TFO-FPs with target polypurine oligonucleotides involve both Watson-Crick and Hoogsteen base-pairings. Through double sensing of oligonucleotide sequences, single mutations of target oligonucleotides are detected by monitoring changes in pyrene fluorescence. The high specificities of the probes are maintained over a wide temperature range without sacrifice of hybridization kinetics.