Figure 1.
Tested metal complex (K34)2Ni(II).
Structural representation of the metal complex (K34)2Ni(II).
Figure 2.
(K34)2Ni(II) shows different binding profiles towards wtTel26 and Tel26 at 25°C.
ITC profiles corresponding to the titration of 25 µM wtTel26 (Panel A) or Tel26 (Panel B) with (K34)2Ni(II) at 25°C in 10 mM Tris, 20 mM KCl, pH 7.5. Raw ITC data (top panel) and binding isotherms (bottom panel).
Table 1.
Thermodynamic parameters derived from ITC titrations describing the interaction of (K34)2Ni(II) with Tel26 and wtTel26 at 25°C in 10 mM Tris, 20 mM KCl, pH 7.5.
Table 2.
Thermodynamic parameters derived from ITC titrations describing the interaction of (K34)2Ni(II) with Tel26, wtTel26 and Tel22 at 37°C in 10 mM Tris, 20 mM KCl, pH 7.5.
Figure 3.
The energetic contribution for (K34)2Ni(II) binding towards tested G-quadruplexes is differently modulated.
Energetic contributions describing the interaction between tested G-quadruplexes and (K34)2Ni(II) at 37°C in 10 mM Tris, 20 mM KCl, pH 7.5. The associated enthalpic variations (ΔH) are shown in black, the entropic ones (-TΔS) in white and the Gibbs energy changes (ΔG) in grey.
Figure 4.
(K34)2Ni(II)-G-quadruplex bound form shows conserved CD spectra features.
Dichroic spectra of 4 µM Tel26 (Panel A), wtTel26 (Panel B), Tel22 (Panel C) or single strand scrambled scT22 (Panel D) in the presence of increasing concentrations of (K34)2Ni(II) at 25°C in 10 mM Tris, 20 mM KCl, at pH 7.5. Arrows indicate changes upon addition of the metal complex, curves in bold indicate spectra of the free oligonucleotide and at 1∶1 and 2∶1 ligand:DNA ratios in panels A–C. In panel D the solid line corresponds to the CD contribution of DNA alone, the dotted line represents the dichroic spectrum at saturating concentrations of (K34)2Ni(II).
Figure 5.
Ligand saturation is modulated by DNA folding.
Fraction of rearranged G-quadruplex (f) induced by increasing concentrations of (K34)2Ni(II) at 25°C in 10 mM Tris, 20 mM KCl, pH 7.5. Oligonucleotides concentration: 4 µM.
Figure 6.
(K34)2Ni(II) promotes G-quadruplex folding of the tested telomeric sequences.
Dichroic spectra of 4 µM Tel 26 in the presence of increasing concentrations of (K34)2Ni(II) at 45 °C (Panel A) and thermal denaturation profiles of the same oligonucleotide (Panel B) recorded at 290 nm in the absence (solid line) or in the presence of (K34)2Ni(II) at 2∶1 molar ratio (dotted line) in 10 mM Tris, 20 mM KCl at pH 7.5.