Interaction between Curcumin and β-Casein: Multi-Spectroscopic and Molecular Dynamics Simulation Methods

Effect of temperature and pH on the interaction of curcumin with beta-casein was explored by fluorescence spectroscopy, ultraviolet-visible spectroscopy and molecular dynamics simulation. The spectroscopic results showed that curcumin could bind to beta-casein to form a complex which was driven mainly by electrostatic interaction. The intrinsic fluorescence of beta-casein was quenched by curcumin through static quenching mechanism. The binding constants of curcumin to beta-casein were 6.48 x 10(4) L/mol (298 K), 6.17 x 10(4) L/mol (305 K) and 5.73 x 10(4) L/mol (312 K) at pH 2.0, which was greater than that (3.98 x 10(4) L/mol at 298 K, 3.90 x 10(4) L/mol at 305 K and 3.41 x 10(4) L/mol at 312 K) at pH 7.4. Molecular docking study showed that binding energy of beta-casein-curcumin complex at pH 2.0 (-7.53 kcal/mol) was lower than that at pH 7.4 (-7.01 kcal/mol). The molecular dynamics simulation study showed that the binding energy (-131.07 kJ/mol) of beta-casein-curcumin complex was relatively low at pH 2.0 and 298 K. alpha-Helix content in beta-casein was decreased and random coil content was increased in the presence of curcumin. These results can promote a deep understanding of interaction between curcumin and beta-casein and provide a reference for improving the bioavailability of curcumin.

Automated summary

The study showed that curcumin can form a complex with beta-casein, mainly driven by electrostatic interaction. The binding energy of the complex was lower under acidic conditions compared to neutral conditions. Additionally, presence of curcumin led to a decrease in alpha-helix content and an increase in random coil content in beta-casein.