Comparison of the binding affinity of Nuc-1,2,3,4-RGG, Nuc-3,4-RGG, and Nuc-RGG for the c-MYC G-quadruplex. 10,000 cpm of radiolabeled oligomer was assembled into a G-quadruplex structure and incubated with Nuc-1,2,3,4-RGG (A), Nuc-3,4-RGG (B), or Nuc-1,2,3,4-RGG (C) at the indicated concentrations in a 20-μL reaction containing 10 mM Tris-HCl, pH 7.4, 1 mM EDTA, 1 mM DTT, 50 ng/μL poly(dI-dC), 4 μg/mL BSA, and 25 mM KCl for 1 h at room temperature.