(A) Melting behavior of a fluorescent G-rich
oligonucleotide (F21T, 0.2 μM strand concentration) alone (crosses)
or in the presence of compound 1 (●,
0.5 μM; ■, 1 μM; ⧫, 2 μM,; ▴, 3 μM).
Excitation was set at 470 nm, and fluorescence emission (arbitrary
units) was recorded at 515 nm. Buffer was 0.1 M LiCl, 10 mM sodium
cacodylate, pH 7.3. (B) Melting behavior of a G-rich
oligonucleotide (F21T, 0.2 μM strand concentration) in the presence
of a 100× molar excess of a double-stranded oligonucleotide (crosses)
but in the absence of any ligand (the curve is nearly identical to that
observed in the absence of double-stranded DNA, see A). The
three other curves were obtained in the presence of compound
1 (1 μM) with no competitor (■) or a 43×
excess of dS26, a double-stranded competitor (●)
or a 100× excess (⧫). Excitation was set at 470 nm, and fluorescence
emission was recorded at 515 nm. Buffer was 0.1 M LiCl, 10 mM sodium
cacodylate, pH 7.3.