Design and Characterization of Chemically Stabilized A尾42 Oligomers

详细信息    查看全文

• 作者：Ghiam Yamin ; Tien-Phat Vuong Huynh ; David B. Teplow
• 刊名：Biochemistry
• 出版年：2015
• 出版时间：September 1, 2015
• 年：2015
• 卷：54
• 期：34
• 页码：5315-5321
• 全文大小：351K
• ISSN：1520-4995

文摘

A popular working hypothesis of Alzheimer鈥檚 disease causation is amyloid 尾-protein oligomers are the key neuropathogenetic agents. Rigorously elucidating the role of oligomers requires the production of stable oligomers of each size. We previously used zero-length photochemical cross-linking to allow stabilization, isolation, and determination of structure鈥揳ctivity relationships of pure populations of A尾40 dimers, trimers, and tetramers. We also attempted to study A尾42 but found that A尾42 oligomers subjected to the same procedures were not completely stable. On the basis of the fact that Tyr is a critical residue in cross-linking chemistry, we reasoned that the chemical accessibility of Tyr10 in A尾42 must differ from that in A尾40. We thus chemically synthesized four singly substituted Tyr variants that placed the Tyr in different positions across the A尾42 sequence. We then studied the stability of the resulting cross-linked oligomers as well as procedures for fractionating the oligomers to obtain pure populations of different sizes. We found that [Phe¹⁰,Tyr⁴²]A尾42 produced stable oligomers yielding highly pure populations of dimers through heptamers. This provides the means to establish formal structure鈥揳ctivity relationships of these important A尾42 assemblies. In addition, we were able to analyze the dissociation patterns of non-cross-linked oligomers to produce a model for oligomer formation. This work is relevant to the determination of structure鈥揳ctivity relationships that have the potential to provide mechanistic insights into disease pathogenesis.