Töpperwien M, Priebe M, Salditt T
Institut für Röntgenphysik, Univ. Göttingen, Friedrich-Hund-Platz 1, 37077, Göttingen, Germany.
Eur Biophys J. 2016 Jul;45(5):383-92. doi: 10.1007/s00249-015-1107-9. Epub 2015 Dec 29.
We have performed scanning nano-beam small-angle X-ray scattering (nano-SAXS) experiments on in vitro-formed actin filaments cross-linked with [Formula: see text]-actinin. The experimental method combines a high resolution in reciprocal space with a real space resolution as given by the spot-size of the nano-focused X-ray beam, and opens up new opportunities to study local super-molecular structures of actin filaments. In this first proof-of-concept, we show that the local orientation of actin bundles formed by the cross-linking can be visualized by the X-ray darkfield maps. The filament bundles give rise to highly anisotropic diffraction patterns showing distinct streaks perpendicular to the bundle axes. Interestingly, some diffraction patterns exhibit a fine structure in the form of intensity modulations allowing for a more detailed analysis of the order within the bundles. A first empirical quantification of these modulations is included in the present work.
我们对与α-辅肌动蛋白交联的体外形成的肌动蛋白丝进行了扫描纳米束小角X射线散射（纳米小角X射线散射）实验。该实验方法在倒易空间中具有高分辨率，并结合了纳米聚焦X射线束光斑尺寸所给出的实空间分辨率，为研究肌动蛋白丝的局部超分子结构开辟了新机会。在这第一个概念验证中，我们表明交联形成的肌动蛋白束的局部取向可以通过X射线暗场图可视化。丝束产生高度各向异性的衍射图案，显示出垂直于束轴的明显条纹。有趣的是，一些衍射图案呈现出强度调制形式的精细结构，从而能够对束内的有序性进行更详细的分析。本工作中包含了对这些调制的首次经验性量化。
