Maurstad Gjertrud, Prass Marcus, Serpell Louise C, Sikorski Pawel
Department of Physics, Norwegian University of Science and Technology, 7491 Trondheim, Norway.
Eur Biophys J. 2009 Oct;38(8):1135-40. doi: 10.1007/s00249-009-0526-x. Epub 2009 Aug 14.
Atomic force microscopy was used to investigate the stability of dehydrated amyloid fibrils formed by human islet polypeptide (IAPP) and Abeta(1-42) peptides. IAPP amyloid fibrils were imaged in liquid (hydrated state) and in air (dehydrated). In addition, fibrils dried on the mica surface were rehydrated and re-examined both in liquid and in air (after consecutive redrying). As reported previously, the initial drying process does not result in any major change in the amyloid appearance and the dimensions of the fibrils are preserved. However, when once-dried samples are rehydrated, fibril stability is lost. The fibrils disintegrate into small particles that are attached to the mica surface. This process is further confirmed by studies of the rehydrated samples after drying, on which the morphology of the fibrils is clearly changed. Similar behavior is observed for Abeta(1-42) amyloid fibrils, which are apparently stable on first drying, but disintegrate on rehydration. The observed change indicates that dehydration is causing a change in the internal structure of the amyloid fibrils. This has important implications for studies of amyloid fibrils by other techniques. Due to the potential influence of hydration and sample history on amyloid structure, preparation and study of amyloid samples with controlled humidity requires more consideration.
原子力显微镜被用于研究由人胰岛多肽（IAPP）和β淀粉样蛋白（1-42）肽形成的脱水淀粉样纤维的稳定性。IAPP淀粉样纤维在液体（水合状态）和空气中（脱水状态）成像。此外，在云母表面干燥的纤维被重新水化，并在液体和空气中（连续重新干燥后）重新检查。如先前报道，初始干燥过程不会导致淀粉样外观的任何重大变化，并且纤维的尺寸得以保留。然而，当一次干燥的样品重新水化时，纤维稳定性丧失。纤维分解成附着在云母表面的小颗粒。干燥后对重新水化样品的研究进一步证实了这一过程，在这些样品上纤维的形态明显改变。对于β淀粉样蛋白（1-42）淀粉样纤维也观察到类似行为，它们在首次干燥时显然稳定，但在重新水化时分解。观察到的变化表明脱水正在导致淀粉样纤维内部结构的改变。这对通过其他技术研究淀粉样纤维具有重要意义。由于水合作用和样品历史对淀粉样结构的潜在影响，在可控湿度下制备和研究淀粉样样品需要更多考虑。
