State Key Laboratory of Food Science and Technology and School of Food Science and Technology, Jiangnan University, Jiangsu, China.
J Agric Food Chem. 2009 Aug 26;57(16):7576-83. doi: 10.1021/jf901585n.
Structural unfolding of soy protein isolate (SPI) as induced by holding (0, 0.5, 1, 2, and 4 h) in acidic (pH 1.5-3.5) and alkaline (pH 10.0-12.0) pH solutions, followed by refolding (1 h) at pH 7.0, was analyzed. Changes in emulsifying properties of treated SPI were then examined. The pH-shifting treatments resulted in a substantial increase in protein surface hydrophobicity, intrinsic tryptophan fluorescence intensity, and disulfide-mediated aggregation, along with the exposure of tyrosine. After the pH-shifting processes, soy protein adopted a molten globule-like conformation that largely maintained the original secondary structure and overall compactness but lost some tertiary structure. These structural modifications, consequently, led to markedly improved emulsifying activity of SPI as well as the emulsion stability.
通过在酸性（pH 1.5-3.5）和碱性（pH 10.0-12.0）pH 溶液中保持（0、0.5、1、2 和 4 h）来诱导大豆分离蛋白（SPI）的结构展开，然后在 pH 7.0 下进行复性（1 h），对其进行分析。然后检查处理后的 SPI 的乳化性能变化。pH 转换处理导致蛋白质表面疏水性、内在色氨酸荧光强度和二硫键介导的聚集显着增加，同时暴露出酪氨酸。在 pH 转换过程之后，大豆蛋白采用类似无定形球蛋白的构象，该构象在很大程度上保持了原始的二级结构和整体紧凑性，但失去了一些三级结构。这些结构修饰，进而导致 SPI 的乳化活性以及乳液稳定性得到明显改善。
