Department of Health Sciences & Technology, Laboratory of Food & Soft Materials, ETH Zurich , 8092 Zurich, Switzerland.
ACS Nano. 2014 Nov 25;8(11):11071-9. doi: 10.1021/nn504249x. Epub 2014 Nov 3.
Protein fibril accumulation at interfaces is an important step in many physiological processes and neurodegenerative diseases as well as in designing materials. Here we show, using β-lactoglobulin fibrils as a model, that semiflexible fibrils exposed to a surface do not possess the Gaussian distribution of curvatures characteristic for wormlike chains, but instead exhibit a spontaneous curvature, which can even lead to ring-like conformations. The long-lived presence of such rings is confirmed by atomic force microscopy, cryogenic scanning electron microscopy, and passive probe particle tracking at air- and oil-water interfaces. We reason that this spontaneous curvature is governed by structural characteristics on the molecular level and is to be expected when a chiral and polar fibril is placed in an inhomogeneous environment such as an interface. By testing β-lactoglobulin fibrils with varying average thicknesses, we conclude that fibril thickness plays a determining role in the propensity to form rings.
蛋白质原纤维在界面处的积累是许多生理过程和神经退行性疾病以及材料设计中的一个重要步骤。在这里，我们以β-乳球蛋白原纤维为例表明，暴露于表面的半柔性原纤维不具有对于类蠕虫链而言典型的曲率高斯分布，而是表现出自发曲率，甚至会导致环状构象。原子力显微镜、低温扫描电子显微镜和空气-水油界面上的被动探针粒子跟踪实验证实了这种环状结构的长时间存在。我们推断这种自发曲率受分子水平上的结构特征控制，当手性和极性的原纤维被置于不均匀的环境（如界面）中时，就会出现这种自发曲率。通过测试具有不同平均厚度的β-乳球蛋白原纤维，我们得出结论，原纤维厚度在形成环的趋势中起决定性作用。
