Deciphering the Interaction of 5,7-Dihydroxyflavone with Hen-Egg-White Lysozyme through Multispectroscopic and Molecular Dynamics Simulation Approaches

In recent times, research based on the bio-active flavonoid, chrysin has shown its potential therapeutic applications such as anti-diabetic, neuroprotective, anti-asthmatic, anti-depressant, etc. In order to understand its molecular recognition process, we studied its interaction with hen egg white lysozyme (HEWL) at physiological conditions. Chrysin (5,7-Dihydroxyflavone) was able to quench the intrinsic fluorescence of HEWL through static quenching mechanism and the binding constant (K-b) was found to be (4.390 +/- 0.088 3104) M-1 at 298 K and it decreased with the increase in temperature. The value of thermodynamic parameters such as Delta H (-17.154 +/- 0.872) kJ mol(-1) and Delta S (+ 31.267 +/- 3.151) J K-1 mol-1 indicated that hydrogen bonding and hydrophobic forces played a central role in the complexation process. Alteration in the Trp micro-environment was induced due to the incorporation of chrysin in the binding site as indicated by synchronous and three dimensional (3D) fluorescence studies. FT-IR and CD studies revealed that the secondary structure of HEWL was altered on chrysin binding, which resulted in an increase in the alpha-helical stability of the protein. Chrysin inhibited the enzymatic activity of HEWL against M. lytus. Molecular docking and molecular simulation studies revealed that hydrogen bonding and hydrophobic forces played a vital role in complexation process. This study provides substantial insight into the binding of a bio-active flavonoid (chrysin) with a carrier protein (HEWL).