Magnesium Ion-Regulated Aggregation Mechanism of Zein–Ovalbumin Complexes

Metal ions can influence protein aggregation behavior through interactions with proteins during food processing, and a deeper understanding of these regulatory mechanisms is crucial for improving the structure and stability of food systems. In this study, the effect of Mg²⁺ on the aggregation behavior of Zein, Ovalbumin, and Zein-Ovalbumin complexes during thermal treatment was discussed using an aggregation kinetic model, and the relationship between protein conformational changes and protein aggregation behavior was revealed by combining theory with experiments. After the addition of Mg²⁺, the aggregation of Zein and Zein-Ovalbumin complexes was inhibited, while the aggregation of Ovalbumin was enhanced. The exposure of hydrophobic and free -SH groups of proteins was determined, thereby regulating the aggregation behavior of complexes. The thermal stability of protein complexes was also enhanced by electrostatic and hydrogen-bonding interactions between Zein and Ovalbumin, which was further validated via Fourier transform infrared spectroscopy and molecular dynamics simulation. Mg²⁺ reduced the binding free energy between proteins within the Zein-Ovalbumin complexes through the electrostatic shielding effect, thereby affecting the energy contributions of key residues. This study provides valuable mechanistic insights for strategically utilizing metal ions such as Mg²⁺ to regulate protein aggregation and optimize functional properties of complex proteins.