Selection and Characterization of DNA Aptamers Targeting All Four Serotypes of Dengue Viruses
Fig 6
Analysis of quadruplex structure.
(A) Native gel was used to determine the folding of S15. Lane 1 and lane 2 are S15 prepared in distilled water and 100 mM KCl. Lane 3 and lane 4 are other 34 mer linear nucleotides prepared in distilled water and 100 mM KCl. Gel mobility of aptamer S15 was faster than linear nucleotides which has same length, suggesting that S15 folds into specific structure as monomer. (B) CD spectra of aptamer S15 in varying concentration of KCl (0 to 50 mM). S15 in 5 mM of KCl showed a negative peak at 240 nm and a positive peak at 264 nm, indicating the formation of parallel quadruplex structure. (C) Illustration of parallel quadruplex structure of aptamer S15 with two G·G·G·G tetrad and external loops. (D) Comparison of CD spectra of aptamer S15, aptamer S15G2 and S15G3. It suggested that aptamer S15 and aptamer S15G3 had the same parallel quadruplex structure.