羟基自由基氧化对大豆分离蛋白结构特性的影响

The Effect of Oxidative Hydroxyl Radical on Structural Characteristics of Soybean Protein Isolate

探讨氧化对大豆分离蛋白结构特性的影响。采用羟基自由基氧化体系,在不同的H2O2浓度(0.1,0.5,1,5,10,15 mmol/L)下对大豆分离蛋白氧化1 h。测定氧化前、后大豆分离蛋白的总巯基和活性巯基,紫外扫描、色氨酸荧光分析以及蛋白聚合物变化趋势。研究结果表明,在氧化条件下,大豆分离蛋白的总巯基和活性巯基含量显著降低(P<0.05);紫外扫描图谱的峰强度明显减弱,出峰位置发生蓝移;色氨酸荧光峰位先红移后蓝移。聚丙烯酰胺凝胶电泳表明,氧化使大豆分离蛋白产生非二硫键的共价交联。氧化能在一定程度上改变大豆分离蛋白的结构特性。

This study mainly investigated the changes of structural properties induced by hydroxyl radical-stressed soybean protein isolate（SPI）. SPI was exposed to a hydroxyl radical-generating system（HRGS） under different H2O2concentrations（0.1-15 mmol/L） for 1 h. The results revealed that the total sulfhydryl and reactive sulfhydryl content decreased as the H2O2 concentration increased（P〈0.05）, while tryptophan fluorescent emission spectrum was observed blueshift and UV-Vis spectra was observed blue-shift after the first red-shift. The SDS-PAGE patterns showed that protein oxidation caused protein aggregation by non-disulphides linkage between proteins. These results showed that structural characteristics of SPI were changed via protein oxidation.