Figure 2.

Kinetics of cation-dependent aptamer folding. (A) Schematic representation of the effect of cations on thrombin-binding aptamer (TBA) and scrambled TBA sequence (TBAsc) folding. Upon G-quadruplex formation the 5′ quencher is brought into proximity of the fluorophore, thus the fluorescence decreases. (B–E) Real-time fluorescence signal (dots) and fits (solid lines) of a representative experiment measuring the association and dissociation phases of: (B) K⁺; (C) NH4⁺; (D) Na⁺; (E) Li⁺ to immobilized TBA carried out in 50 mM Tris. Binding signal to TBA is referenced with binding signal to TBAsc.