Modulating immune reactivity of grass carp parvalbumin via pulsed electric field-induced variation of structural properties

The mechanism of PEF treatment (5–20 kV/cm for 0.5–2 h) changing spatial conformation and enhancing allergenicity of parvalbumin of grass carp was clarified, and molecular dynamics simulations (MDS) was utilized to explore hot-spot residues and epitopes of parvalbumin-IgE complex. The phenomenon revealed that the IgG and IgE binding capacity of parvalbumin maximally enhanced by 37.24 % and 27.63 % respectively, but subsequently decreased after 20 kV/cm exposure for 1 h. Atomic force microscope showed that the particle morphology of PEF-treated parvalbumin became more regular and homogeneous, with dissociation of aggregates due to decreased hydrophobic interaction. Furthermore, 5–20 kV/cm treatments promoted conformation unfolded and de-spiralization, rendering it easy for target antibodies to interact with related epitopes. MDS showed that the critical epitopes between parvalbumin and IgE were phenylalanine58, glutamate60–61, aspartate91, aspartate93-glycine96 and glutamate102 with ΔG < −1 kcal/mol, and hot-spot residues were phenylalanine, glutamate and aspartate with ΔΔG > 1 kcal/mol.