Fig. 2. Biophysical characterization of berberine and coptisine binding to the KRAS-G4.
a CD thermal melting curves and CD spectra of Pu24m1 DNA with berberine and coptisine, respectively. Conditions: 20 μM DNA, pH 7, 15 mM K+ solution. b Fluorescence intensity change of berberine and coptisine upon titration with Pu24m1 DNA, respectively. Conditions: 0.2 μM compound, pH 7, 50 mM K+ solution. c The determined ΔTm and Kd values of berberine and coptisine to the Pu24m1 DNA. The melting temperature (Tm) was obtained at the intersection between the median of the fitted baselines and the melting curve. The dissociation constant (Kd) was calculated by data fitting with a 2:1 binding equation. The experiments were run in duplicate.