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Gel Phase Membrane Retards Amyloid β-Peptide (1–42) Fibrillation by Restricting Slaved Diffusion of Peptides on Lipid Bilayers

Yang, Mengting, Wang, Kang, Lin, Jiake, Wang, Liqun, Wei, Feng, Zhu, Jintao, Zheng, Wanquan, Shen, Lei
Langmuir 2018 v.34 no.28 pp. 8408-8414
Alzheimer disease, amyloid beta-peptides, brain, fluorescence microscopy, gels, humans, lipid bilayers, lipids, liquids, neurotoxicity, pathogenesis, plasma membrane, spectroscopy
Plasma membranes in the human brain can interact with amyloid β-peptide (1–42; Aβ₄₂) and induce Aβ₄₂ fibrillation, which is considered to be a crucial process underlying the neurotoxicity of Aβ₄₂ and the pathogenesis of Alzheimer’s disease (AD). However, the mechanism of membrane-mediated Aβ₄₂ fibrillation at the molecular level remains elusive. Here we study the role of adsorbed Aβ₄₂ peptides on membrane-mediated fibrillation using supported lipid bilayers of varying phase structures (gel and fluid). Using total internal reflection fluorescence microscopy and interfacial specific second-order nonlinear optical spectroscopy, we show that the dynamics of 2D-mobile Aβ₄₂ molecules, facilitated by the highly mobile lipids underneath the peptides, are critical to Aβ₄₂ fibrillation on liquid phase membranes. This growth mechanism is retarded on gel phase membranes where the dynamics of 2D-mobile peptides are restricted by the “frozen” lipids with less mobility.