Investigation into the site-specific binding interactions between chlorogenic acid and ovalbumin using multi-spectroscopic and in silico simulation studies

The binding interactions of bioactive compounds with proteins are of great importance in the food, biochemistry and pharmaceutical fields. Herein, the binding mechanisms between 5-O-caffeoylquinic acid (5-CQA) and ovalbumin (OVA) were investigated by multi-spectroscopic studies combined with docking and molecular dynamics (MD) simulations. The emission intensity of OVA was quenched by 5-CQA and Stern-Volmer analysis indicated the existence of a static suppression by OVA-5-CQA complex formation. Thermodynamic parameters revealed that the formation of complex was spontaneously driven by electrostatic and hydrogen-bonding interactions. Circle dichroism analyses showed that 5-CQA decreased the α-helix content of OVA structure from 58.05% to 54.32% upon increased OVA:5-CQA ratio to 1:3. Molecular docking results suggested 5-CQA forms hydrogen bond interactions with N88, T91, K92, N94, S98, F99, S100 and L101 residues of OVA. The experimental values were in good agreement with the calculated binding free energy values obtained by MD simulation (R2 = 0.89).Communicated by Ramaswamy H. Sarma.