Figure 3.

Screening of the leaving group for the G-4 alkylation. (A) Alkylation by acridine-VQ-X precursors. The precursor ligand (50 μM) was incubated with G-quadruplex (G-4), double-stranded (ds) or single-stranded (ss) DNA (2.5 μM) at 37°C in buffer solution (2% DMSO). G-4 phosphate buffer (K⁺): 100 mM KCl, 10 mM K₂HPO₄/ KH₂PO₄ (pH 7.0), 1 mM K₂EDTA; ds and ss buffer: 100 mM NaCl, 10 mM Na₂HPO₄/NaH₂PO₄ (pH 7.0), 1 mM Na₂EDTA. (B) The target sequences. (C) Denaturing gel electrophoresis of the alkylation products for G-4. Lanes 1 and 14 are for control (G-4 DNA without ligand). The electrophoresis was performed on a 16% denaturing polyacrylamide gel containing 20% formamide. (D) Time course of the reaction yields for 3-SMe, 3-S(O)Me, 3-SPh and 3-S(O)Ph. (E) Bar graph of yield (%) at 12 h for 3-SMe, 3-S(O)Me, 3-SPh and 3-S(O)Ph (n = 3, error bars indicate standard deviation).