Complexation of thrombin-binding aptamer oligonucleotide carrying fluorescence resonance energy transfer (FRET) dyes at both termini with potassium ion.

Abstract

Oligonucleotide derivatives, F-TBA-T and F-7TBA-T carrying thrombin-binding aptamer (TBA) sequence and FAM and TAMRA dyes at their each end were designed to achieve the fluorometric monitoring of potassium ion (K+) concentrations in a living organisms. These oligonucleotides could form a tetraplex structure upon addition of K+. Spectrophotometric experiments revealed that the fluorescence enhancement on the fluorescence resonance energy transfer (FRET) was larger in the case of F-7TBA-T having 7-nucleotides at 5'-end of TBA sequence than in the case of F-TBA-T due to the elimination of the quenching by dye-dye interaction.