Multispectral analysis and molecular simulation of quinoa protein-tannic acid interactions: Conformational changes and functional properties

Abstract

This study used multispectral analysis and molecular simulation to investigate the mechanisms of non-covalent interactions between quinoa protein isolate (QPI) and tannic acid (TA), and its effects on protein conformation. The formation of the QPI-TA complex was confirmed by increased turbidity, polyphenol binding capacity, and UV–visible absorbance. The addition of TA decreased α-helices while increasing β-sheets and random coils, resulting in a looser, more disordered protein structure of QPI. Thermodynamic analysis and molecular docking results indicated that the predominant interactions between QPI and TA are hydrophobic interactions and hydrogen bonds. Molecular dynamics simulations confirmed that the binding sites of TA and QPI were tightly associated, thereby maintaining conformational stability. Additionally, the non-covalent modification by TA significantly enhanced the emulsifying and foaming capacities of QPI. This study provides a theoretical foundation for the application of QPI-polyphenol complexes in the production of emulsified foods.