乳液中柔性界面蛋白构效关系研究

Structure and Flexibility Analysis of Interface Protein in Protein Emulsion

摘要:

乳液的稳定性取决于形成的水油界面处蛋白膜的稳定性，研究界面蛋白的构效关系对蛋白工业化生产十分重要。提取了不同品种大豆蛋白乳液的界面蛋白，分析了界面蛋白的结构特征，并通过对界面蛋白溶解性和乳化性质的分析，解析蛋白质柔性结构对功能性质的影响机制。结果表明，柔性较高的蛋白可以更快吸附到油滴表面，结构更易伸展；柔性较高的界面蛋白中疏水性氨基酸含量较高，表面疏水性增加，其二级结构中α-螺旋结构含量较低，无规则卷曲结构含量较高；紫外光谱和荧光光谱分析表明，界面蛋白质分子在解折叠后暴露出更多的疏水性基团，其溶解性降低，在水油界面处易形成稳定的蛋白膜，从而增加乳液的稳定性。

Abstract:

The stability of soybean protein emulsion depends on the stability of protein membrane at oil-water interface. It is important to study the structure and functional property of interface protein of different protein emulsions. Totally 12 varieties of different interface protein were extracted. The interface flexible protein had higher content of hydrophobic amino acids, and the molecular weight of the protein contained mainly more than 100ku. The globulin subunits of 7S and 11S protein were analyzed by FTIR. The content of α-helix was lower and the content of random coil was higher, which was consistent with the above results of different flexible SPIs. From the composition of SDS-PAGE subunits, it could be seen that the proportion of 7S in the flexible protein was increased, which further proved that 7S protein had higher flexibility. The flexibility of the interface protein was higher. The result of surface hydrophobicity of interface protein was the same as that of SPI, and the interface protein had more hydrophobic residues to be stable at the water-oil interface. From the analysis of the tertiary structure of the interface protein by UV and fluorescence spectrum, it could be seen that the amino acid residues of the interface flexible protein were more exposed and the structure was more flexible, which was conducive to the molecular rearrangement at the interface. The functional properties were also changed, the solubility was decreased and the emulsification was increased, which was related to the structure features of the interface proteins.