糖基化改性对大豆蛋白抗原性及结构特性的影响

Effects of Glycation Modification on Soybean Protein Antigenicity and Structural Properties

以大豆分离蛋白和葡聚糖为原料,在干热条件下进行美拉德反应,制取不同时间下的糖基化复合物。以β-伴大豆球蛋白和大豆球蛋白抗原抑制率为指标,采用间接竞争ELISA方法测定糖基化产物的抗原性,在反应6 d时,糖基化产物中β-伴大豆球蛋白和大豆球蛋白的抗原性分别降低了36.90%和18.12%。糖基化产物颜色加深,且游离氨基含量降低,说明大豆蛋白与糖发生了不同程度的反应。红外光谱中糖链的引入,使蛋白质分子展开,β-转角和无规则卷曲结构含量降低,影响了β-伴大豆球蛋白α亚基的抗原表位,从而可能使大豆蛋白的抗原性降低。糖基化反应影响抗原性的关键作用在于蛋白与糖结合部位对蛋白质结构变化的影响。

Soy protein isolate （SPI） and dextran were used as raw materials and SPI -dextran conjugate were prepared under dry -heated at different times through Maillard reaction in this paper. The antigen inhibition rate of β - eonglycinin and glycinin in SPI - dextran conjugate were tested with indirect competitive ELISA method. The an- tigenicity of β - conglycinin and glycinin decreased 36.90% and 18.12% respectively when the reaction processed at 6 d. Meanwhile, the color deepened and the free amino group content reduced which indicated that different degrees of reaction occurred between soy protein isolate with dextran. FTIR indicated that the protein structure of glycated samples unfolded as the introduced sugar chains. The reduced β - comer and random coil structure content impacted the epitope of β - conglycinin antigen in soybean protein, and then reduced the antigenicity of soybean protein. These showed that the key effect relies on the structure changes caused by the binding site between protein and saccharide.