Compressibility of insulin amyloid fibrils determined by X-ray diffraction in a diamond anvil cell

Amyloid fibrils are fibrous structures that originate from the self-assembly of polypeptides. Their formation is linked to debilitating diseases associated with protein misfolding, including Alzheimer's disease and type-II diabetes. In recent years, it has been suggested that such protein and polypeptide fibrils might provide useful novel nanomaterials. Here, we present the results of a study on the high pressure stability and compressibility of mature amyloid fibrils of insulin by synchrotron X-ray diffraction in a diamond anvil cell. The diffraction results allow a direct estimation of the elastic modulus and the corresponding compression of the cross- structure along the fiber axis. The average hydrogen bond compressibility is comparable to that in native proteins, suggesting that the fibrils are well-packed.