Enhancing protein interactions in Zein-β-lactoglobulin complexes by (-)-Epigallocatechin-3-gallate: Expanding the potential of molecular glues in food application

Abstract

Enhancing protein-protein interactions (PPIs) has been intensively studied, and the use of molecular glues is a cutting-edge technology. Although the number of molecular glues approved by the Food and Drug Administration is limited, (−)-Epigallocatechin-3-gallate (EGCG) has shown potential as a molecular glue. This study aimed to investigate how EGCG regulated the mechanism of PPIs using zein and β-lactoglobulin (β-LG) as model proteins. The molecular dynamics simulations revealed that EGCG enhanced hydrogen bonding and hydrophobic interactions in Zein-β-LG complexes, thereby improving their stability and compactness. The ΔG values for the formation of the complexes were all higher than −20 kcal/mol, suggesting strong protein interactions and spontaneous binding process. To validate the theoretical calculations, experimental verification was also conducted. The turbidity, particle size, and ζ-potential results demonstrated that EGCG enhanced the aggregation and stability of Zein-β-LG complexes. Fluorescence experiments indicated that the ΔG values at 298K were −27.57 kJ‧mol⁻¹ at pH 5.5, −26.26 kJ‧mol⁻¹ at pH 7.0, and −25.58 kJ‧mol⁻¹ at pH 2.5, and the corresponding binding sites were 1.036, 1.018, and 1.118, respectively. Thermodynamic parameters suggested that hydrogen bonding and hydrophobic interactions were the main driving forces involved in the complexation of EGCG and Zein-β-LG. EGCG binding significantly altered the secondary structures and surface properties of the complexes. These insights emphasized the potential of EGCG in modulating protein interactions, with significant implications for protein-based material and delivery system in the food and pharmaceutical industries.