Small-Angle X-ray Scattering Study of Protein Complexes with Tea Polyphenols
Small-Angle X-ray Scattering Study of Protein Complexes with Tea Polyphenols
复制标题
茶多酚蛋白质复合物的小角 X 射线散射研究
DOI：
10.1021/acs.jafc.6b04630
复制
发表时间：
2017-01-25
影响因子：
6.1
通讯作者：
Li, Yunqi
中科院分区：
文献类型：
--
作者：
Shi, Ce;Tang, Haifeng;Li, Yunqi
探索蛋白质复合物的结构，特别是蛋白质与配体结合后的构象变化和聚集行为，对于在分子水平上阐明其生物活性至关重要。应用溶液小角X射线散射（SAXS）技术研究了茶多酚（儿茶素和表没食子儿茶素没食子酸酯）与牛血清白蛋白（BSA）和胰蛋白酶结合的复合物结构。我们发现，茶多酚可以通过其桥接作用稳定地促进蛋白质和蛋白质复合物的聚集。从SAXS强度分布图中提取复合物和复合物聚集体中的蛋白质的数量，并讨论了它们作为多酚与蛋白质的摩尔比的函数的依赖性。EGCG比儿茶素具有更强的促进复合物形成和进一步聚集的能力，并且复合物的聚集体具有相对光滑的表面和更致密的核心。儿茶素诱导的聚集体松散堆积，表面粗糙。在形成折叠良好的复合物时，BSA比胰蛋白酶表现出更高的稳定性。胰蛋白酶的协同解折叠导致含有更多茶多酚的混合物中的更大聚集体。使用荧光光谱法进一步确定结合到每种蛋白质的茶多酚的结合亲和力和数量。在这项工作中探索的蛋白质复合物的结构在蛋白质复合物为基础的颗粒的制备和多酚诱导的蛋白质复合物的形成和进一步聚集的理解是可理解的。
Exploration of the structure of protein complexes, especially the change in conformation and aggregation behavior of proteins upon ligand binding, is crucial to clarify their bioactivities at the molecular level. We applied solution small-angle X-ray scattering (SAXS) to study the complex structure of bovine serum albumin (BSA) and trypsin binding with tea polyphenols, that is, catechin and epigallocatechin gallate (EGCG). We found that tea polyphenols can steadily promote the aggregation of proteins and protein complexes through their bridging effect. The numbers of proteins in the complexes and in the aggregates of complexes are extracted from SAXS intensity profiles, and their dependences as a function of the molar ratio of polyphenol to protein are discussed. EGCG has stronger capability than catechin to promote complex formation and further aggregation, and the aggregates of complexes have a denser core with a relatively smooth surface. The aggregates induced by catechin are loosely packed with a rough surface. BSA shows higher stability than trypsin in the formation of complex with a well-folded conformation. The synergistic unfolding of trypsin results in larger aggregates in the mixtures with more tea polyphenols. The binding affinity and number of tea polyphenols bound to each protein are further determined using fluorescence spectroscopy. The structure of protein complexes explored in this work is referable in the preparation of protein complex-based particles and the understanding of polyphenol-induced formation and further aggregation of protein complexes.