关键词: β-乳球蛋白, DHA, 黄原胶, 相互作用, 抗原性, 结构

Abstract: β-lactoglobulin (β-LG) can induce severe allergic reactions. In this study, the effects of Xanthan gum (XG) and Docosahexaenoic Acid (DHA) synergistically modifying β-lactoglobulin on its antigenicity and structural characteristics were investigated. The complexes DHA-β-LG, DHA-β-LG-XG were obtained using non-covalent binding. The antigenicity studies and structural characterization of complexes were carried out using indirect competitive enzyme linked immunosorbent assay, particle size analysis, three-dimensional fluorescence spectroscopy, fourier transform infrared spectroscopy, simultaneous fluorescence spectroscopy, ultraviolet spectroscopy and molecular docking techniques. The results showed that the antigenicity of ternary complex DHA-β-LG-XG was significantly reduced compared with that of β-LG and binary complex DHA-β-LG. The strongest inhibition of immunoglobulin G (IgG) binding capacity was achieved with 2.5 mg/mL XG, with an inhibition rate of 24.81%±0.27%. The ternary complex DHA-β-LG-XG was more stable than the binary complex DHA-β-LG. As the concentration of XG increased, the particle size of the complex DHA-β-LG-XG increased and then decreased. Under coexisting XG and DHA conditions, β-LG exhibited increased β-sheet and β-turn content with decreased α-helix and random coil content. Furthermore, the exposure levels of both fluorophores and peptide bonds in β-LG showed a linear positive correlation with XG concentration. XG is inserted into the only hydrophobic cavity of β-LG, and DHA binds to the hydrophobic pocket on the surface of β-LG. Both XG and DHA form a ternary complex with β-LG through hydrogen bonding, electrostatic interactions, and hydrophobic interactions.

Key words: β-lactoglobulin (β-LG), Docosahexaenoic Acid (DHA), Xanthan gum (XG), interaction, allergenicity, structure