Chapter 9 Crystallization of Photosynthetic Membrane Proteins

Abstract

Publisher Summary Photosynthesis is one of the most important processes on earth as it converts light energy into chemical energy. The first and most important steps of this process are catalyzed by large membrane protein complexes that are involved in light capturing, energy transfer, and electron transfer. In the past 15 years, great progress has been made towards the crystallization and structure determination of the antenna complexes and photoreaction centers, which are the most complex membrane proteins that have been crystallized to date. This chapter summarizes the important factors that have been critical for the successful crystallization of the large protein-cofactor complexes, with a special focus on the lessons learned from the crystallization and structure determination of Photosystems I and II (PSI and PSII, respectively). Photosynthetic membrane proteins have long been an active focus of research. This was partially because of the fact that these proteins are responsible for the production of all oxygen in the atmosphere. Photosynthetic organisms are the primary producers of nearly all the biomass and bioenergy produced on the earth. From a practical point of view, they are abundant in their source organisms, and their pigment content facilitates tracking them in their native form in experiments. Because of its high importance, it comes as no surprise that the first membrane protein crystallized was a photosynthetic protein complex, the photosynthetic reaction center of Rhodopseudomonas viridis .