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. [Display omitted] •Z15 exhibited great specific activity (75.57 U/mg) and thermostability (Tm 72.4 °C).•SPI nanoparticles treated with Z15 showed dramatic increase in functional properties.•SPI nanoparticles treated with Z15 presented excellent homogeneity and stability.•Glu81 and Glu113 were key residues with big energy contribution in 7S-Z15 complexes.