RESULTS: We propose two artificial β-sheets which can mimic the nanoscopic structural characteristics of pathogenic oligomers and fibrils for evaluating the performance of a label free, X-ray based biomarker detection and quantification technique. Highly similar structure with elliptical cross-section and parallel cross-β motif is observed among recombinant α-synuclein fibril, Aβ-42 fibril and artificial β-sheet fibrils. We then use these β-sheet models to assess the performance of spectral small angle X-ray scattering (sSAXS) technique for detecting β-sheet structures. sSAXS showed quantitatively accurate detection of antiparallel, cross-β artificial oligomers from a tissue mimicking environment and significant distinction between different oligomer packing densities such as diffuse and dense packings.
CONCLUSIONS: The proposed synthetic β-sheet models mimicked the nanoscopic structural characteristics of β-sheets of fibrillar and oligomeric states of Aβ and α-synuclein based on the ATR-FTIR and SAXS data. The tunability of β-sheet proportions and shapes of structural motifs, and the low-cost of these β-sheet models can become useful test materials for evaluating β-sheet or amyloid specific biomarkers in a wide range of neurological diseases. By using the proposed synthetic β-sheet models, our study indicates that the sSAXS has potential to evaluate different stages of β-sheet-enriched structures including oligomers of pathogenic proteins.
结果:我们提出了两种人工β-折叠,可以模拟致病性寡聚体和原纤维的纳米级结构特征,用于评估无标签的性能,基于X射线的生物标志物检测和定量技术。在重组α-突触核蛋白原纤维中观察到具有椭圆形横截面和平行交叉β基序的高度相似结构,Aβ-42原纤维和人工β-折叠原纤维。然后,我们使用这些β-折叠模型来评估光谱小角X射线散射(sSAXS)技术用于检测β-折叠结构的性能。sSAXS显示了反平行的定量准确检测,来自组织模拟环境的cross-β人工寡聚物,以及不同寡聚物堆积密度之间的显着区别,例如扩散和致密堆积。
结论:所提出的合成β-折叠模型基于ATR-FTIR和SAXS数据模拟了Aβ和α-突触核蛋白的原纤维和寡聚状态的β-折叠的纳米级结构特征。β-折叠比例和结构基序形状的可调性,这些β-折叠模型的低成本可以成为在广泛的神经系统疾病中评估β-折叠或淀粉样蛋白特异性生物标志物的有用测试材料。通过使用提出的合成β-折叠模型,我们的研究表明,sSAXS有潜力评估β-折叠富集结构的不同阶段,包括致病蛋白的寡聚体。