CRYSTALLIZATION OF REACTION CENTERS FROM RHODOBACTER SPHAEROIDES

The crystallization of proteins is usually accomplished by a trial and error approach that is guided by a large body of empirically determined procedures and conditions. Although a systematic approach to investigate the mechanisms of crystallization of water soluble proteins has been developed, these investigations have so far not been extended to membrane proteins. This chapter discusses the conditions used to crystallize the reaction center (RC) in several different forms are compared and the sensitivity of the crystallization to various parameters. Two sets of conditions were originally used to grow different crystal forms of RCs from Rhodobacter sphaeroides. One set were similar to the conditions used to crystallize RCs from Rps. viridis. The other set corresponded approximately to the conditions used to crystallize porin from E. coli. The growth of the different forms was influenced by “traditional” crystallization parameters such as salt and protein concentrations, pH, and temperature.