Spectroscopic Investigation of Emetine–DNA Binding

Emetine, a natural isoquinoline alkaloid with broad pharmacological potential, interacts with DNA through specific noncovalent mechanisms. Using UV-vis spectroscopy, FTIR spectroscopy, and molecular docking, this study examined the mode and energetics of emetine-DNA association. UV-vis spectra displayed pronounced hypochromic and bathochromic shifts upon DNA titration, indicating strong chromophore-base pair interactions. The binding constant (<i>K</i> = 1.10 × 10⁶ M^-1) and Gibbs free energy (Δ<i>G</i>° = -8.26 kcal·mol^-1) confirm a spontaneous, moderately strong interaction. FTIR analysis revealed perturbations in guanine and phosphate vibrations, consistent with hydrogen bonding and π-π stacking effects. Docking simulations with B-DNA (PDB: 1BNA) identified a low-energy binding pose (Δ<i>G</i> = -7.13 kcal·mol^-1), positioning emetine within the DNA minor groove and forming hydrogen bonds with guanine DG4. Together, spectroscopic and computational data support a minor groove-associated binding model and establish a foundation for future high-resolution structural studies of emetine-DNA interactions.