Formation Mechanism and Morphology Control of Glutenin Microtubes Prepared Using Acid-Heat Treatment

The morphology, polymorphism transformation, and influencing factors on self-assembly growth of acid-heat-treatment-induced glutenin amyloid fibers (GAFs) were investigated by multiple techniques. The results showed that GAFs were hollow microtubes with thread-like structures on the surface formed by twisting of filaments composed of low-molecular-weight glutenin aggregates (35, 41, and 57 kDa), conforming to the monomer model. β₂-type antiparallel sheet plays a critical role in forming GAF cross-β structures. Moderate glutenin concentrations (3-7%) facilitated fibril longitudinal and radial growth, whereas the massive instantaneous nucleation at higher concentrations inhibited further growth. Low pH significantly enhanced energy change dominated by electrostatic repulsion, reducing the twisting angle, and increasing the fiber length and pitch. Salt ions with concentration examined induced protein aggregation through electrostatic shielding, delaying the self-assembly process and hindering the longitudinal growth of fibers. The polymorphism transformation of the fibers from microtubes to ribbons and their moduli can be controlled by solvent polarity.