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 (K = 1.10
× 106 M–1) and Gibbs free energy
(ΔG° = −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 (ΔG = −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.