Structural insights into acidic heating-induced amyloid fibrils derived from soy protein as a function of protein concentration

Amyloid fibrillation of food-derived dietary proteins has been increasingly accepted as an effective approach to enhance protein functionality. Soy protein, an abundant and environmentally sustainable protein, has been widely used in food applications. However, the mechanism for amyloid fibrillation at various protein concentrations during the acidic heating process is not fully understood, along with an incomplete understanding of the structural polymorphism. In this study, we systematically investigated the influence of protein concentration on amyloid fibrillation of soy protein by means of atomic force microscopy (AFM), 1-anililo-naphthalene-8-sulfonate (ANS) and thioflavin T (Th T) fluorescence, reducing sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and Fourier transform infrared spectrometer (FTIR). AFM analysis showed that soy protein-derived amyloid fibrils (SAFs) demonstrated very rich and diverse polymorphism and exhibited at least five kinds of longrigid fibrils that had distinct periodicity, height, and handedness. The polypeptides hydrolysis behavior and the parallel to antiparallel fi-sheet ratios were found to be protein concentration-dependent. Results obtained from this study will lead to a deeper understanding of formation mechanism of SAFs and lay the foundation for SAFs severing as functional ingredients in food field.

Automated summary

In this study, the influence of protein concentration on the amyloid fibrillation of soy protein was systematically investigated. The results showed that soy protein-derived amyloid fibrils exhibited rich and diverse polymorphism, with at least five distinct types of longrigid fibrils. The behavior of polypeptide hydrolysis and the ratio of parallel to antiparallel beta-sheets were found to be dependent on protein concentration. These findings contribute to a deeper understanding of the formation mechanism of soy protein-derived amyloid fibrils and lay the foundation for their potential use as functional ingredients in the food industry.