Protein Deamidation Reduced Digestive Resistance and Amyloid Antigenicity of Soy Proteins via Depolymerization

Abstract

Soy protein remains a key component of plant-based food development, but its application is challenged by inherent allergenicity. Previous work identified that native amyloid-like protein aggregates in soy 7S globulin that resist gastrointestinal digestion and exhibit pronounced antigenicity. Herein, we demonstrate that protein deamidation significantly enhances proteolysis under an in vitro infant gastrointestinal digestion model, leading to ∼80 and 50% reductions in IgG- and IgE-binding capacities, respectively. Moreover, deamidation induced the oligomerization of 7S globulin aggregates, and QCM-D analysis confirmed that this transition effectively suppressed antigen–antibody interactions. Importantly, molecular dynamics simulations further revealed that deamidation altered the surface charge distribution of the α c ′ homotrimer of β-conglycinin, and the charge reversal (from positive to negative) hindered protein self-organization, thereby attenuating the amyloid antigenicity of 7S globulin. These findings provide mechanistic insights into how structural modulation of food protein aggregates governs their antigenic behavior during digestion.