Department of Biochemistry, Collage of Science, King Saud University, P.O. Box 2455, Riyadh, 11451, Saudi Arabia.
Department of Biochemistry, Collage of Science, King Saud University, P.O. Box 2455, Riyadh, 11451, Saudi Arabia.
Colloids Surf B Biointerfaces. 2023 Sep;229:113481. doi: 10.1016/j.colsurfb.2023.113481. Epub 2023 Jul 27.
The mechanism by which anionic surfactants promote amyloid fibril is not well understood. Here, we investigated how sodium dodecyl sulfate (SDS), a negatively charged surfactant, affects the fibrillation of the partially unfolded random-coiled bovine liver catalase (BLC) at a pH of 2.0. We used several methods, including turbidity, RLS kinetics, intrinsic fluorescence, ThT fluorescence, far-UV CD, and TEM imaging, to evaluate the conformational changes of BLC in vitro in response to SDS treatment. BLC is a multimeric protein and well folded at physiological pH but forms a random coil structure at pH 2.0. Intrinsic fluorescence and far-UV CD data showed that below 0.1 mM SDS, random coiled BLC turned into a native-like structure. BLC incubated with an SDS concentration ranging from 0.1 to 2.0 mM led to the formation of aggregates. The ThT fluorescence intensity was enhanced in the aggregated BLC samples (0.1-2.0 mM SDS), and cross beta-sheeted structure was detected by the far UV CD measurements. BLC adopts a complete alpha-helical structure upon interacting with SDS at a more than 2.0 mM concentration at pH 2.0. Understanding the mechanism of surfactant- or lipid-induced fibrillation is important for therapeutic purposes.
阴离子表面活性剂促进淀粉样纤维形成的机制尚不清楚。在这里，我们研究了带负电荷的表面活性剂十二烷基硫酸钠（SDS）如何影响部分展开的无规卷曲牛肝过氧化氢酶（BLC）在 pH 值为 2.0 时的纤维化。我们使用了几种方法，包括浊度、RLS 动力学、内源荧光、ThT 荧光、远紫外 CD 和 TEM 成像，来评估 BLC 在体外对 SDS 处理的构象变化。BLC 是一种多聚体蛋白，在生理 pH 值下折叠良好，但在 pH 值为 2.0 时形成无规卷曲结构。内源荧光和远紫外 CD 数据表明，低于 0.1 mM SDS 时，无规卷曲的 BLC 变成类似天然的结构。BLC 与 SDS 浓度在 0.1 到 2.0 mM 之间孵育会导致聚集物的形成。在聚集的 BLC 样品（0.1-2.0 mM SDS）中，ThT 荧光强度增强，并且通过远紫外 CD 测量检测到交叉β-折叠结构。在 pH 值为 2.0 时，BLC 在浓度高于 2.0 mM 的 SDS 作用下采用完全α-螺旋结构。了解表面活性剂或脂质诱导纤维化的机制对于治疗目的很重要。
