Charge Dependent Retardation of Amyloid β Aggregation by Hydrophilic Proteins
Charge Dependent Retardation of Amyloid β Aggregation by Hydrophilic Proteins
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DOI：
10.1021/cn400124r
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发表时间：
2014-04-01
影响因子：
5
通讯作者：
Linse, Sara
中科院分区：
文献类型：
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作者：
Assarsson, Anna;Hellstrand, Erik;Linse, Sara
淀粉样蛋白β多肽(Aβ)聚集成淀粉样蛋白纤维与阿尔茨海默病的病理机制有关。鉴于已报道的抑制Aβ纤维形成的蛋白质数量不断增加，我们研究了不同电荷的小分子亲水性模型蛋白对Aβ聚集动力学的影响及其与Aβ的相互作用。在钙结合蛋白D9k和单链Monellin的6种电荷变体存在下，我们用硫代黄素T荧光跟踪了Aβ40和Aβ42的淀粉样纤维的形成。用透射电子显微镜证实了纤维的形成。我们观察到净电荷为+8、+2、−2和−4的蛋白质的聚集过程被延缓，而净电荷为−6和−8的蛋白质对聚集过程没有影响。净电荷最高的单链Monellin突变体SCMN+8对淀粉样原纤维的形成有最大的延缓作用，其摩尔比低至0.01：1SCMN+8和Aβ40时显著延迟。通过表面等离子体共振检测，SCMN+8也是与Aβ40结合最快的突变体，尽管Calbindin D9k和单链Monellin的所有延缓变异体都与Aβ40结合。
The aggregation of amyloid β peptides (Aβ) into amyloid fibrils is implicated in the pathology of Alzheimer’s disease. In light of the increasing number of proteins reported to retard Aβ fibril formation, we investigated the influence of small hydrophilic model proteins of different charge on Aβ aggregation kinetics and their interaction with Aβ. We followed the amyloid fibril formation of Aβ40 and Aβ42 using thioflavin T fluorescence in the presence of six charge variants of calbindin D9kand single-chain monellin. The formation of fibrils was verified with transmission electron microscopy. We observe retardation of the aggregation process from proteins with net charge +8, +2, −2, and −4, whereas no effect is observed for proteins with net charge of −6 and −8. The single-chain monellin mutant with the highest net charge, scMN+8, has the largest retarding effect on the amyloid fibril formation process, which is noticeably delayed at as low as a 0.01:1 scMN+8 to Aβ40 molar ratio. scMN+8 is also the mutant with the fastest association to Aβ40 as detected by surface plasmon resonance, although all retarding variants of calbindin D9kand single-chain monellin bind to Aβ40.