Functional, structural properties and interaction mechanism of soy protein isolate nanoparticles modified by high-performance protein-glutaminase

Investigating the changes in the structural and functional properties of soy protein isolate (SPI) modified by high-performance protein-glutaminase (PG) and understanding their interactions are crucial for the application of SPI nanoparticles. Herein, the thermal stability and activity of PG were evolved by computer-assisted rational design strategy, generating the best variant Z15 (N16M/N20L/Q21H/K48R/S81E/T113E) with a 4.65-fold improved activity (75.57 U/mg) and increased thermal stability (ΔTm = 4.6 °C), one of the best performing PG. SPI treated with Z15 showed better solubility, foaming, and emulsifying properties than the wild type PG-deamidation, which were increased by 1.25-fold, 45.45%, and 38.95%, respectively. Furthermore, SPI treated with Z15 exhibited lower hardness and higher cohesiveness. By systematically analyzing the structural characteristics, SPI nanoparticles possessed a coarse, loose, and porous microstructure. Molecular dynamics simulations suggested that the Glu81 and Glu113 residues of Z15 contributed the most to the stabilization interaction in β-conglycinin-Z15 complexes. These results could provide theoretical guidance for the potential application of SPI nanoparticles in sustainable green plant-based foods industries.