β-乳球蛋白与二十二碳六烯酸互作效应对β-乳球蛋白致敏性机制的影响

Impact of Interaction with Docosahexaenoic Acid on the Allergenicity ofβ-Lactoglobulin

β-乳球蛋白(β-lactoglobulin,β-LG)是牛乳中的主要过敏原,以β-LG为原料,采用三维荧光光谱法、圆二色谱法、分子模拟对接法和间接竞争酶联免疫吸附测定法探究二十二碳六烯酸(docosahexaenoic acid,DHA)与β-LG互作效应及其对β-LG致敏性的影响。结果表明:DHA与β-LG结合后显著改变了β-LG中芳香族残基的微环境,使其极性增加;DHA通过疏水作用力与β-LG结合形成稳定复合物,且结合后,β-LG的二级结构发生改变,蛋白质骨架发生折叠,随着DHA浓度的增加,β-折叠相对含量先增加后减少,α-螺旋相对含量的变化与β-折叠相反,β-转角、无规卷曲相对含量变化没有明显规律;此外,在两者结合后,β-LG的抗原性降低,DHA浓度为3 mmol/L时,免疫球蛋白E结合能力抑制率约为29%。

β-Lactoglobulin(β-LG)is a major allergen in cow’s milk.In this study,synchronous fluorescence spectroscopy,three-dimensional fluorescence spectroscopy,circular dichroism(CD)spectroscopy,molecular docking,and indirect competitive enzyme-linked immunosorbent assay were used to explore the interaction of docosahexaenoic acid(DHA)withβ-LG and its influence on the allergenicity ofβ-LG.The results showed that the binding of DHA toβ-LG significantly changed the microenvironment of the aromatic residues ofβ-LG and increased its polarity.DHA bound toβ-LG to form a stable complex through hydrophobic interactions,changing the secondary structure ofβ-LG and resulting in folding of its backbone.The relative content ofβ-sheet increased and then decreased with increasing concentration of DHA,while the relative content ofα-helix showed an opposite trend.However,the relative contents ofβ-turn and random coil showed irregular changes.In addition,the antigenicity ofβ-LG decreased after combination with DHA,and the immunoglobulin E(IgE)binding ability inhibition rate was about 29%by 3 mmol/L DHA.