Fig. 2. ATP-mediated dimerization of split sequences in homogeneous solution. (A) Page: lane 1, DNA marker; lane 2, S1; lane 3, S2; lane 4, S1 + S2 + ATP (+); lane 5, S1 + S2 + ATP (++); lane 6, S1 + S2 + ATP (+++). S1 and S2 = 1.0 μM. ATP (+) = 0.1 mM, ATP (++) = 0.5 mM, ATP (+++) = 1.0 mM. (B) Melting curves of the split sequence mixture (S1 and S2) in the absence or presence of ATP (1.0 mM). Fluorescence intensity of the split sequence mixture with SYBR Green I as a function of temperature. Inset: Negative first derivative of the melting curves. (C) CD spectra of the split sequence mixture in the presence of ATP. (D) G-quadruplex-induced fluorescence enhancement of ThT resulting from the ATP-mediated dimerization of split sequences.