Determining the binding mode and binding affinity constant of tyrosine kinase inhibitor PD153035 to DNA using optical tweezers

► PD153035 is a DNA intercalator and intercalation occurs only under very low salt concentration. ► The minimum distance between adjacent bound PD153035 ≈ 11 bp. ► Binding affinity constant for PD153035 is 1.18(±0.09) × 104 (1/M). ► The change of binding free energy of PD153035-DNA interaction is −5.49 kcal mol−1 at 23 ± 0.5 °C.