Failure of Alzheimer’s Aβ(1–40) amyloid nanofibrils under compressive loading |
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Authors: | Raffaella Paparcone Markus J Buehler |
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Affiliation: | (1) Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, MN, USA;(2) Laboratory for Neurophysics and Intelligence Modeling, Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA; |
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Abstract: | Amyloids are associated with severe degenerative diseases and show exceptional mechanical properties, in particular great
stiffhess. Amyloid fibrils, forming protein nanotube structures, are elongated fibers with a diameter of ≈8 nm with a characteristic
dense hydrogen-bond (H-bond)patterning in the form of beta-sheets (β-sheets). Here we report a series of molecular dynamics
simulations to study mechanical failure properties of a twofold symmetric Aβ(l–40) amyloid fibril, a pathogen associated with
Alzheimer’s disease. We carry out computational experiments to study the response of the amyloid fibril to compressive loading.
Our investigations reveal atomistic details of the failure process, and confirm that the breakdown of H-bonds plays a critical
role during the failure process of amyloid fibrils. We obtain a Young’s modulus of ≈12.43 GPa, in dose agreement with earlier
experimental results. Our simulations show that failure by buck-ling and subsequent shearing in one of the layers initiates
at ≈1% compressive strain, suggesting that amyloid fibrils can be rather brittle mechanical elements. |
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