Mechanical manipulation of Alzheimer's amyloid beta1-42 fibrils

J Struct Biol. 2006 Aug;155(2):316-26. doi: 10.1016/j.jsb.2005.12.015. Epub 2006 May 2.


The 39- to 42-residue-long amyloid beta-peptide (Abeta-peptide) forms filamentous structures in the neuritic plaques found in the neuropil of Alzheimer's disease patients. The assembly and deposition of Abeta-fibrils is one of the most important factors in the pathogenesis of this neurodegenerative disease. Although the structural analysis of amyloid fibrils is difficult, single-molecule methods may provide unique insights into their characteristics. In the present work, we explored the nanomechanical properties of amyloid fibrils formed from the full-length, most neurotoxic Abeta1-42 peptide, by manipulating individual fibrils with an atomic force microscope. We show that Abeta-subunit sheets can be mechanically unzipped from the fibril surface with constant forces in a reversible transition. The fundamental unzipping force (approximately 23 pN) was significantly lower than that observed earlier for fibrils formed from the Abeta1-40 peptide (approximately 33 pN), suggesting that the presence of the two extra residues (Ile and Ala) at the peptide's C-terminus result in a mechanical destabilization of the fibril. Deviations from the constant force transition may arise as a result of geometrical constraints within the fibril caused by its left-handed helical structure. The nanomechanical fingerprint of the Abeta1-42 is further influenced by the structural dynamics of intrafibrillar interactions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alzheimer Disease / metabolism*
  • Amyloid beta-Peptides / chemistry*
  • Elasticity
  • Humans
  • Microscopy, Atomic Force / methods
  • Models, Molecular
  • Peptide Fragments / chemistry*
  • Protein Structure, Secondary


  • Amyloid beta-Peptides
  • Peptide Fragments
  • amyloid beta-protein (1-42)