大豆球蛋白的纤维聚集体行为及其稳定性研究

为了明确蛋白质的纤维聚集行为,本研究以大豆球蛋白(soy globulin,11S)为原料,从亚基层面对酸性条件下热诱导的11S纤维聚集过程进行跟踪,监测蛋白及其亚基的水解过程、结构变化及其稳定性。结果表明,11S的纤维化是一个多步骤的过程,包括多肽链的水解、自组装成淀粉样纤维聚集结构及逐渐生长成宏观可见的具有扭曲螺旋结构的纤维聚集体。与11S纤维化过程的单指数增长相比,酸性亚基的纤维化过程存在迟滞期。酸性亚基在纤维化聚集的初期主要贡献于纤维聚集的成核过程,碱性亚基的加入改变其纤维聚集进程。蛋白质的纤维化过程会增加11S在等电点处的溶解度,降低中性和酸性pH下的溶解度。此外,碱性环境(pH值10.0)会导致11S纤维聚集体全部溶解、宏观纤维长度变小、结构发生改变。以上研究结果旨在为合理利用蛋白纤维化聚集体作为新的功能性食品配料提供理论依据。

Fibrillar Aggregation Behavior and Stability of Soy Globulin

In order to better define fibrillar aggregation behavior of protein, the heat-induced soy globulin (11S) fiber aggregation process under acidic conditions was investigated in the subunit level to monitor the hydrolysis process, structural change and stability of the protein and its subunits by using 11S as raw material. The hydrolysis kinetics results showed that the fibrillar aggregation process of 11S was a multistep process, including the hydrolysis of polypeptide chains, self-assembly into amyloid fibrils aggregates and the gradual accumulation of macroscopically visible fibrous aggregates with twisted helical structures. Compared with the single exponential growth of the 11S fibrosis process, the fibrosis process of the acidic subunits was delayed. The acidic subunits mainly contributed to the nucleation process of fibril aggregation in the early stage, while the addition of basic subunits could change the process of fibril aggregation. The fibril aggregates of protein could increase the solubility of 11S at isoelectric point and decrease the solubility at neutral acidic pH. In addition, the alkaline environment (pH 10.0) would cause 11S fiber aggregates to dissolve completely, and the macroscopic fiber length becomes shorter and the structure changes. The results might provide a theoretical basis for the rational use of soy protein fibril aggregates as a novel functional food ingredient.