超高压处理对乳清分离蛋白结构及致敏蛋白含量的影响

以乳清分离蛋白为研究对象,通过测定圆二色性光谱、巯基含量以及内源性荧光光谱等研究了不同超高压水平(100、200、400和600 MPa)对其二级、三级结构的影响,并采用水解度测定、十二烷基硫酸钠-聚丙烯酰胺凝胶电泳以及2个标志性致敏蛋白(β-乳球蛋白和α-乳白蛋白)含量的检测来解析超高压对乳清分离蛋白致敏性的影响。结果表明,超高压处理能够使乳清分离蛋白的α-螺旋和β-转角部分转化为β-折叠和无规则卷曲,可以增强乳清分离蛋白的巯基含量,在400 MPa时,表面巯基含量提高了104.82%,也造成了乳清分离蛋白内源性荧光强度的显著变化以及最大吸收波长的红移,电泳图谱以及水解度未显示出明显差异。通过酶联免疫吸附实验原理检测致敏蛋白含量发现,超高压可以使α-乳白蛋白含量显著减少,但是,400 MPa的超高压处理却使β-乳球蛋白含量增加。综上表明,超高压处理能够显著改变乳清分离蛋白的二级、三级结构,暴露出结构内部的疏水基团,并对致敏蛋白产生影响。

Effects of ultra-high pressure on the structure of whey protein isolate and the content of allergenic protein

In this study,whey protein isolate(WPI)was subjected to ultra-high pressure(UHP)at different treatments(100、200、400 and 600 MPa).The secondary and tertiary structures of WPI was studied by measuring circular dichroism(CD),sulfhydryl groups content,and endogenous fluorescence spectroscopy.The degree of hydrolysis(DH),sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-page),and the contents of two marker sensitizing proteins,β-lactoglobulin(β-LG)andα-lactalbumin(α-LA),were used to analyze the effect of UHP on the sensitization of WPI.The results showed that the UHP treatment transformed theα-helix andβ-turn of WPI into aβ-sheet and random coil.And it also enhanced the sulfhydryl contents of WPI.At 400 MPa,the surface sulfhydryl content increased by 104.82%.The UHP treatment also caused a significant change in the endogenous fluorescence intensity of WPI and red shift of maximum absorption wavelength.The SDS-page pattern and degree of hydrolysis of the samples treated with UHP did not show significant differences.Furthermore,ELISA detection found that UHP could significantly reduce the content ofα-LA,however,the UHP treatment at 400MPa increased the content ofβ-LG.These results indicate that UHP can significantly alter the secondary and tertiary structure of WPI,expose the hydrophobic groups inside the structure,and influence its allergenic protein.