Main application in Cryo-TEM: Single Particle Analysis and Tomography
Single particle analysis (SPA) and tomography can both be performed on the same microscope and they provide complementary information. SPA can deliver high-resolution images of a molecular complex, but lacks biological context. Electron tomography can provide contextual information but has limited resolution of individual particles.
Electron tomography is a well-established technique for recording images at various tilts and subsequent back-projection into a 3D reconstruction (Video 1). The sample can be a purified macromolecular complex, a whole virus, or even an entire cell.
Single particle analysis (SPA) is another way to create 3D images. With this technique data from a large number of two dimensional projection images, featuring identical copies of a macromolecule in different orientations, are combined to generate a3D reconstruction of the structure (Video 2).
Animations courtesy of Max Planck Institute of Biochemistry, Martinsried, Germany