Characterization of the Nanoscale Properties of Individual Amyloid Fibrils

• Published in: Proceedings of the National Academy of Sciences - PNAS 2006-10, Vol.103 (43), p.15806-15811
• Main Authors: Smith, Jeffrey F., Knowles, Tuomas P. J., Dobson, Christopher M., MacPhee, Cait E., Welland, Mark E.
• Format: Article
• Language: English
• Subjects: Amyloid - chemistry; Amyloid - metabolism; Amyloid - ultrastructure; Amyloids; Animals; Bending; Biological Sciences; Cattle; Insulin; Insulin - chemistry; Insulin - metabolism; Kinetics; Microscopy; Microscopy, Atomic Force; Nanostructures - chemistry; Nanostructures - ultrastructure; Pathogens; Polymers; Protein Binding; Proteins; Solar fibrils; Spectroscopy; Spectrum analysis; Spring constant; Stiffness; Structural deflection
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0604035103

We report the detailed mechanical characterization of individual amyloid fibrils by atomic force microscopy and spectroscopy. These self-assembling materials, formed here from the protein insulin, were shown to have a strength of 0.6 ± 0.4 GPa, comparable to that of steel (0.6-1.8 GPa), and a mechanical stiffness, as measured by Young's modulus, of 3.3 ± 0.4 GPa, comparable to that of silk (1-10 GPa). The values of these parameters reveal that the fibrils possess properties that make these structures highly attractive for future technological applications. In addition, analysis of the solution-state growth kinetics indicated a breakage rate constant of 1.7 ± 1.3 x 10⁻⁸ s⁻¹, which reveals that a fibril 10 ¼m in length breaks spontaneously on average every 47 min, suggesting that internal fracturing is likely to be of fundamental importance in the proliferation of amyloid fibrils and therefore for understanding the progression of their associated pathogenic disorders.