Radermacher M, Wagenknecht T, Verschoor A, Frank J
J Microsc. 1987 May;146(Pt 2):113-36. doi: 10.1111/j.1365-2818.1987.tb01333.x.
We present a new reconstruction method that takes advantage of the fact that many biological macromolecular assemblies show a preferred orientation with respect to the plane of the specimen grid in the electron microscopic preparation. From one micrograph taken of such a specimen tilted by a large angle, a conical tilt series with random azimuthal angles can be extracted and used for a three-dimensional reconstruction. Our technique allows the determination of the molecular structure under low-dose conditions, which are not achievable with reconstruction methods that use conventional tilt series. The reconstruction method combines a number of existing image processing techniques with a newly developed weighted back-projection algorithm designed for three-dimensional reconstruction from projections taken with arbitrary projecting directions. The method is described as it was applied to the three-dimensional reconstruction of the structure of the 50S ribosomal subunit of Escherichia coli (E. coli).
我们提出了一种新的重建方法，该方法利用了这样一个事实：在电子显微镜制备过程中，许多生物大分子组装体相对于样品网格平面呈现出优先取向。从一张对这样一个大角度倾斜的样品拍摄的显微照片中，可以提取出具有随机方位角的锥形倾斜序列，并将其用于三维重建。我们的技术能够在低剂量条件下确定分子结构，这是使用传统倾斜序列的重建方法无法实现的。该重建方法将多种现有的图像处理技术与一种新开发的加权反投影算法相结合，该算法专为从具有任意投影方向的投影进行三维重建而设计。本文描述了该方法应用于大肠杆菌50S核糖体亚基结构三维重建的情况。
