Abstract:

The interaction of various resveratrol dimers with cobra neurotoxin (NT) was simulated with DiscoveryStudio software.Then,the dimer was photo- induced by light with a wavelength of 365 nm,and the UV- Vis andfluo- rescence spectra of NT mixed with resveratrol were analyzed at different resveratrol concentrations and illumina-tion durations.Finally,the binding energy and some other parameters of the interaction were calculated.The re-sults show that (1) resveratrol dimer is of higher binding energy and stronger interaction than the monomer; (2)some changes occur in the spectra after the illumination,such as enhanced ultra- violet absorption,red- shifted ab-sorption peak,fluorescence quenching and new emission peak; (3) the fluorescence quenching is a static quench-ing with a rate constant of 5.62 × 10 12 L/( mol · s); (4) the binding constant of resveratrol and NT is 5.12 ×10 5 L/mol,the number of binding sites is 1,and the binding distance is 3.40 nm,which may easily resultin non- radiation energy transfer; (5) as illustrated by synchronous fluorescence spectra,the dimer can interact withtyrosin and tryptophan residues of NT and hydroxyl hydrogen bonds may contribute to the improvement of hydrophi-licity; and (6) the main interaction site of NT with resveratrol dimer is the tryptophan residue.

Key words: resveratrol dimer, cobra neurotoxin, interaction, binding energy, UV- Vis spectrum, fluorescencespectrum