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Abstract

In recent years, electron crystallography has been a very successful means of determining the high-resolution structure of many proteins, such as bacteriorhodopsin, the light-harvesting complex, porins (PhoE and OmpF), protein extracted from the ootheca of the praying mantis, archaebacterial surface layers, acetylcholine receptor, Ca²⁺ - ATPase and gp32^∗ l crystals. This success was based on advanced low-dose cryoelectron microscopy and a highly sophisticated digital image-processing methodology which takes into account the radiation damage caused by electron exposure. Particularly successful has been the structure determination of the purple membrane where, by combining biochemical information with the electron-microscopical density maps, the amino acid chains of bacteriorhodopshin have been localized with high precision.