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Characterization of early stage intermediates in the nucleation phase of Aβ aggregation
journal contribution
posted on 2023-05-17, 13:38 authored by Zhai, J, Lee, TH, David SmallDavid Small, Aguilar, M-IAlzheimer's disease (AD) is a common form of dementia, which is characterized by the presence of extracellular amyloid plaques comprising the amyloid β peptide (Aβ). Although the mechanism underlying AD pathogenesis remains elusive, accumulating evidence suggests that the process of amyloid fibril formation is a surface-mediated event, which plays an important role in AD onset and progression. In this study, the mechanism of Aβ aggregation on hydrophobic surfaces was investigated with dual polarization interferometry (DPI), which provides real-time information on early stages of the aggregation process. Aggregation was monitored on a hydrophobic C18 surface and a polar silicon oxynitride surface. The DPI results showed a characteristic Aβ aggregation pattern involving a decrease in the density of Aβ at the surface followed by an increase in the thickness on the hydrophobic C18 chip. Most importantly, the DPI measurements provided unique information on the early stages of Aβ aggregation, which is characterized by the presence of initially slow nucleus formation process followed by exponential fibril elongation. The dimensions of the putative nucleus corresponded to a thickness of ~5 nm for both Aβ40 and Aβ42, which may represent about 10-15 molecules. The results thus support the nucleation-dependent polymerization model as indicated by the presence of a nucleation phase followed by an exponential growth phase. These results are the first reported measurements of the real-time changes in Aβ molecular structure during the early stages of amyloid formation at the nanometer level.
History
Publication title
BiochemistryVolume
51Issue
6Pagination
1070-1078ISSN
0006-2960Department/School
Menzies Institute for Medical ResearchPublisher
Amer Chemical SocPlace of publication
1155 16Th St, Nw, Washington, USA, Dc, 20036Rights statement
Copyright 2012 American Chemical SocietyRepository Status
- Restricted