Electron tomography of paracrystalline 2D arrays.
Electron tomography of paracrystalline 2D arrays.
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DOI：
10.1007/978-1-62703-176-9_23
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Taylor KA
中科院分区：
文献类型：
--
作者：
Winkler H;Wu S;Taylor KA
准晶体阵列具有特定类型的无序，当在重复的模体上进行空间平均时，这些无序降低了结构信息和分辨率。电子断层扫描结合基序分类和平均可以解决异质性问题，并提供引起无序的结构元素的信息。本章描述了在典型的层析成像应用中用于识别和表征准晶样品的程序。特别强调了主动收缩昆虫飞行肌肉，这是一种特别难以表征结构异质性的标本，以及肌球蛋白-V的二维准晶阵列，从中获得了特别高分辨率的基序平均。描述了研究的所有方面，包括数据收集、显微图像的合并以产生断层图像、对不变结构元素的对齐、异质结构的分类和平均、以及将聚焦的类平均重新组装成原始原始重复序列的高信噪比表示。特别强调了产生最终班级平均数的各种过程的局限性。
Paracrystalline arrays possess specific types of disorder that reduce the structural information as well as resolution when spatially averaged over repeating motifs. Electron tomography combined with motif classification and averaging can solve the heterogeneity problem and provide information on the structural elements that give rise to the disorder. This chapter describes procedures that would be used in a typical tomography application to identify and characterize a paracrystalline specimen. Particular emphasis is given to actively contracting insect flight muscle, a specimen with particularly difficult to characterize structural heterogeneity and 2-D paracrystalline arrays of myosin-V, from which a particularly high resolution motif average was obtained. All aspects of the study are described including data collection, merging of micrographs to produce the tomogram, alignment to an invariant structural element, classification and averaging of heterogeneous structures, and reassembly of focused class averages into high signal-to-noise ratio representations of the original raw repeats. Particular emphasis is placed on limitations of the various processes to produce the final class averages.