Collecting electron crystallographic data of two-dimensional protein crystals.

Similar to X-ray crystallography, which requires three-dimensional (3D) crystals, electron crystallography is used to obtain structural information for proteins that form two-dimensional (2D) crystals. However, unlike data collection in X-ray crystallography, which is typically fast and straightforward, data collection in electron crystallography can take months to years and requires substantial expertise. In this contribution, we first discuss the proper preparation of 2D crystals for electron microscopy, which, besides the quality of the 2D crystals, may be the most defining parameter for successful data collection. In the second part, we describe the procedures used to record high-resolution images and diffraction patterns.