STUDY ON THE RELATIONSHIP BETWEEN THE STRUCTURE OF THE SUGAR MOIETIES OF PLANT ALLERGENS AND THEIR ALLERGENICITIES

如今，食物过敏已成为一个严重的社会问题。人们对食品中的过敏原进行了积极的研究，发现了大量的过敏原。然而，与乳果综合征一样，过敏原之间也有一些相似之处。例如，植物过敏原中的糖部分被认为具有共同的抗原性。我们观察到类似的现象发生在Gly m b28k和Tri a b17k。在本研究中，我们研究了Gly m bd28k和Tri a bd17k的糖部分结构与它们的致敏性之间的关系。已克隆出编码Gly m bd28k的cDNA。该cDNA产物与南瓜MP27/MP32和胡萝卜球蛋白样蛋白具有高度同源性。与南瓜蛋白的氨基酸序列比较表明，该过敏原是由南瓜蛋白的前蛋白形成的。过敏原对应于产品的前半部分。利用pGEX-6T表达载体，在大肠杆菌中以谷胱甘肽s -转移酶融合蛋白的形式表达重组过敏原。然而，重组过敏原对Gly - bd28k敏感患者血清中的IgE抗体反应较弱。从脱脂大豆片中纯化的变应原用赖氨酸内肽酶得到的糖肽对IgE抗体有较强的反应，而糖肽的去糖基化肽对IgE抗体无反应。这些发现表明，过敏原的糖部分与患者血清中的IgE抗体结合，并且糖部分在许多植物糖蛋白过敏原中作为共同的抗原决定因素。

Nowaday, food allergy is becoming a great social problem. Allergens in food have been actively elucidated and a great number of the allergens have been found. However, as the latex-fruit syndrome, some similarity among allergens have been pointed out. As an example, the sugar moieties in plant allergens are proposed to show a common antigenicity. We observed similar phenomena cas to Gly m Bd 28K and Tri a Bd 17K.In the present study, we examined the relationship between the structure of the sugar moieties of Gly m Bd 28K and Tri a Bd 17K and their allergenicities.A cDNA encoding Gly m Bd 28K has been cloned. The product for cDNA has been shown to exhibit high homology with pumpkin MP27/MP32 and a carrot globulin-like protein. In comparison of the amino acid sequence of the product with that of the pumpkin protein, the allergen was indicated to be formed via a preproprotein from its proprotein. The allergen corresponded to the former half part of the product. Furthermore, a recombinant allergen was expressed as a fusion protein with glutathione S-transferase in Eschericia coli using an expression vector pGEX-6T.However, the recombinant allergen showed weak response against IgE antibodies in the sera of Gly m Bd 28K-sensitive patients. The glycopeptide obtained with lysyl endopeptidase from the allergen which was purified from defatted soybean flakes, showed strong response to the IgE antibodies, but the deglycosylated peptide from the glycopeptide did not react with the IgE antibodies. These findings suggest that the sugar moiety of the allergen binds to IgE antibodies in the sera of the patients, and that the sugar moiety acts as a common antigenic determinant in many plant glycoproteinic allergens.