Polyphenol-Driven Structural Alterations and Antibacterial Potency of the IgY-Catechin Complex

The binding of proteins with polyphenols can alter the properties of the proteins, thereby expanding their application scenarios. Yolk immunoglobulin (IgY), an easily obtainable protein from eggs, undergoes property changes upon binding with catechin, which is significant for broadening the application of IgY. This study investigates the binding modes, structural changes, stability, and antibacterial properties of the IgY-catechin complex using computational chemistry, spectroscopy, and antibacterial assays. Molecular dynamics simulations analysis revealed that catechin binds to residues PHE503, THR501, THR505, GLU511 of IgY respectively. Fourier transform infrared spectroscopy(FT-IR) and circular dichroism(CD) displayed an increase in hydrogen bond content within the complex, a 5.48% increase in α-helix content, and a decrease in random coil content. Scanning electron microscopy (SEM) showed that the complex had a smoother and more regular surface. The IgY-catechin complex exhibited improved acid-base stability but slightly reduced thermal stability compared to IgY. Fluorescence inverted microscopy and nucleic acid-protein leakage assays indicated that the complex disrupted the cell membranes of both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), leading to the leakage of intracellular genetic material. These findings confirmed that the interaction between catechin and IgY altered the protein structure of IgY, enhanced its bacteriostatic ability. This research provides a new approach to extending the application range of IgY and improving its comprehensive utilization.