Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovský Sq. 2, 162 06 Prague 6, Czech Republic.
Soft Matter. 2021 Feb 19;17(6):1614-1627. doi: 10.1039/d0sm01829e.
The formation of amyloid fibrils from certain proteins stays behind a number of pathologies, so-called amyloidoses. Glycosaminoglycans are polysaccharides and are known natural constituents of amyloids in vivo. However, little is known about the effect of other naturally abundant polysaccharides, and even less is known about the effect of chemically modified polysaccharides on the formation of amyloid fibrils. In the case of low-molecular weight compounds, aromatic substances are known to often influence amyloid formation significantly. We investigated the influence of glycogen (GG) and several modifications of GG with cinnamoyl groups, benzoyl groups and phenylacetyl groups. As model systems, hen egg-white lysozyme (HEWL) and amyloid beta peptide (1-42) (Aβ1-42), which is an Alzheimer disease-relevant system, were used. The fluorescence of thioflavin-T (ThT) was used for the rapid detection of fibrils, and the fluorescence results were confirmed by transmission electron microscopy (TEM). Other techniques, such as isothermal titration calorimetry (ITC) and dynamic light scattering (DLS), were employed to determine the interactions between HEWL and the modifications. We achieved similar results with both model systems (HEWL and Aβ1-42). We showed that π-π interactions played an important role in the process of amyloid fibril formation because fundamental changes were observed in this process even with a very small number of groups containing an aromatic ring. It was found that almost all GG modifications accelerated the formation of amyloid fibrils in both model systems, HEWL and Aβ1-42, except for GG-Ph1 (1.6 mol% phenylacetyl groups), which had a retarding effect compared to all other modifications.
某些蛋白质形成淀粉样纤维是许多病理学的基础，这些病理学被称为淀粉样变性。糖胺聚糖是一种多糖，是体内淀粉样物的天然成分。然而，人们对其他天然丰富的多糖的影响知之甚少，对化学修饰的多糖对淀粉样纤维形成的影响知之更少。在低分子量化合物的情况下，已知芳香物质通常会显著影响淀粉样形成。我们研究了糖原（GG）和几种用肉桂酰基、苯甲酰基和苯乙酰基修饰的 GG 对淀粉样纤维形成的影响。作为模型体系，我们使用了鸡卵清溶菌酶（HEWL）和淀粉样β肽（1-42）（Aβ1-42），这是一个与阿尔茨海默病相关的体系。噻唑蓝（ThT）的荧光用于快速检测纤维，并用透射电子显微镜（TEM）确认荧光结果。还使用了等温滴定量热法（ITC）和动态光散射（DLS）等其他技术来确定 HEWL 和修饰物之间的相互作用。我们在两个模型体系（HEWL 和 Aβ1-42）中都得到了相似的结果。我们表明，π-π 相互作用在淀粉样纤维形成过程中起着重要作用，因为即使只含有一个芳香环的基团数量非常少，这个过程也会发生根本性的变化。结果发现，除了 GG-Ph1（1.6 mol% 苯乙酰基）外，几乎所有的 GG 修饰物都能加速两个模型体系（HEWL 和 Aβ1-42）中淀粉样纤维的形成，而 GG-Ph1 与所有其他修饰物相比具有延缓作用。
