Fluorescence energy transfer probes based on the guanine quadruplex formation for the fluorometric detection of potassium ion.
Dual-labeled oligonucleotide derivative, FAT-0, carrying 6-carboxyfluorescein (FAM) and 6-carboxy-tetramethylrhodamine (TAMRA) labels at 5'- and 3'-termini of thrombin-binding aptamer (TBA) sequence 5'-GGTTGGTGTGGTTGG-3' and its derivatives, FAT-n (n=3, 5, and 7) were designed and synthesized. FAT-n derivatives contained a T(m)A spacer (m=2, 4, and 6, respectively) at 5'-end of TBA sequence. The probes were developed to estimate the spacer effect on FRET efficiency and to identify the best probe for sensing of K(+). Circular dichroism (CD), UV-vis absorption, and fluorescence studies revealed that all FAT-n probes could form the intramolecular tetraplex structures after binding K(+). Association constants of particular K(+)/FAT-n complexes were determined using different experimental approaches. Suitability of particular probes for sensitive monitoring of K(+) in intra- and extracellular conditions was examined and discussed. Calibration graphs of fluorescence ratio were linear in the K(+) concentration range of 2-10 mM for extracellular conditions showing sensitivity of 1.2% mM(-1) K(+) and for intracellular conditions in the range of 100-200 mM with sensitivity of 0.49% mM(-1) K(+).
Nagatoishi
Satoru
S
Department of Applied Chemistry, Kyushu University, Motooka 819-0395, Japan.
Nojima
Takahiko
T
Galezowska
Elzbieta
E
Gluszynska
Agata
A
Juskowiak
Bernard
B
Takenaka
Shigeori
S
D004247:DNA / Q000032:analysis / Q000737:chemistry*; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D005456:Fluorescent Dyes / Q000032:analysis* / Q000737:chemistry; D005470:Fluorometry / Q000379:methods; D054856:G-Quadruplexes; D006147:Guanine / Q000032:analysis / Q000737:chemistry*; D009841:Oligonucleotides / Q000032:analysis / Q000737:chemistry; D011188:Potassium / Q000032:analysis* / Q000737:chemistry
D005456:Fluorescent Dyes; D009841:Oligonucleotides; D006147:Guanine; D004247:DNA; D011188:Potassium