不同长度糖链对α-乳白蛋白过敏表位^(13)KDLKGYGGVSLPEW^(26)结构和致敏性的影响

Effects of Different Lengths Sugar Chains on the Structure and Allergenicity of Allergic Epitopes^(13)KDLKGYGGVSLPEW^(26)in α-Lactalbumin

α-乳白蛋白的过敏表位是影响其致敏性强弱的分子基础,本文研究不同长度的糖链对其过敏表位结构和致敏性的影响。先合成α-乳白蛋白的IgE线性过敏表位(^(13)KDLKGYGGVSLPEW26,13K-W^(26)),选用葡萄糖、麦芽糖、麦芽三糖、麦芽五糖对其进行糖基化修饰,采用光谱、色谱分析其结构的变化;运用ELISA和细胞实验等方法来评价其IgE结合能力和KU812细胞释放组胺、白介素-4和白介素-6的能力。结果表明:不同长度的糖链与13K-W26发生糖基化反应后,降低其游离氨基含量,改变其荧光强度和紫外吸收强度,同时降低其IgE结合能力和KU812细胞中组胺、白介素-4和白介素-6的释放能力。因此,不同长度的糖链能改变13K-W26的结构,降低其致敏性,顺序为麦芽五糖>麦芽三糖>麦芽糖>葡萄糖。糖链可遮蔽α-乳白蛋白的线性表位13K-W26,糖链越长,遮蔽作用越强,致敏性消减效果越好。

The allergic epitopes ofα-lactalbumin are the molecular basis for allergenicity.In this paper,the effects of different lengths sugar chains on the structure and allergenicity of allergic epitopes inα-lactalbumin were investigated.The IgE linear epitopes of ^(13)KDLKGYGGVSLPEW^(26)(13K-W26)were synthesized and glycated with glucose,maltose,maltotriose and maltopentaose.Then the structural changes were analyzed by spectroscopy and chromatography.Cellular assays and ELISA were used to evaluate the histamine,interleukin-4 and interleukin-6 release ability of KU812 cells and the IgE binding ability.The results showed that ^(13)K-W^(26) was glycated by different lengths sugar chains significantly decreased the free amino content and changed the fluorescence intensity and UV absorption intensity,and decreased the IgE binding ability and the release ability of histamine,interleukin-4 and interleukin-6 in KU812 cells.Therefore,different lengths of sugar chains can change the structure of ^(13)K-W^(26),and reduce the allergenicity.The order was maltopentaose>maltotriose>maltose>glucose.In conclusion,the sugar chains could mask the linear epitopes 13K-W26 ofα-lactalbumin,the sugar chains with longer length had stronger masking effects on epitopes,the better the effect of reducing the allergenicity.