热诱导菜豆属7S球蛋白纤维聚集研究

Heat-Induced Fibrillar Aggregation of 7S Globulins (vicilins) from Phaseolus Legumes

摘要:

研究了菜豆属球蛋白(芸豆和绿豆)在低pH低离子强度条件下热诱导形成的自组装纤维聚集机理。通过对制备的球蛋白进行热性质及临界形成凝胶浓度分析，选定85 ℃和0.5%作为自组装纤维化的参数。通过硫代黄色素T(Th T)荧光法，动态光散射(DLS)和原子力显微镜（AFM）表征蛋白纤维化聚集程度及形态。结果表明：芸豆和绿豆球蛋白的Th T最大荧光强度在1h之内剧烈增大（分别是765和1093），表明芸豆和绿豆球蛋白自组装纤维化的“构筑单元”主要产生于加热的起始阶段。DLS结果显示芸豆自组装纤维聚集的能力比绿豆强。但是二者的自组装机理有所不同。AFM图清晰地显示了芸豆球蛋白在加热12 h时自组装形成规则的高度有序的“念珠串状”长线性纤维，绿豆则形成无规则的短棒状纤维和大量碎片状纤维。这为研究进一步研究超低固形物下基于自组装技术的纤维型植物蛋白凝胶的制备提供参考。

Abstract:

The heat-induced fibrillar aggregations of 7S Globulins (vicilins) from kidney bean (Gk) and mung bean (Gm) at low pH and low ionic strength were characterized using dynamic light scattering (DLS), Thioflavin T (Th T) fluorescence assay and atomic force microscopy (AFM). According to thermal characteristics and phase diagram analysis, 85 °C and 0.5% were chosen as denaturation temperature and proper protein concentration. Results also showed that heating led to fibrillar aggregation. Th T maximum fluorescence intensity of Gk and Gm increased dramatically to 765 and 1093 within one hour, indicating that the building blocks were formed at the initial heating periods. DLS data suggested Gk exhibited stronger ability of self assembly and fibrillar aggregation. However, the extent of aggregation and morphology of formed fibrils varied distinctly. AFM data displayed clearly that Gk formed linear fibrils but Gm formed random fibrils upon heating for 12h. This would give experiment data for preparation of transparent gels at extremely low weight fractions plant proteins based on self-assembly.