Abstract
In green algae and higher plants, three extrinsic proteins of OEC33, 24, and 18 associate with photosystem II and play important roles. In order to understand their functions, it is essential to solve their 3D structures. For this purpose, it is needed to grow good-quality crystals suitable for X-ray structure analysis. Here we tried to purify and crystallize OEC18, which has not been crystallized so far. At first, we purified OEC18 from spinach and obtained microcrystals with a length of 100μm. Since the thin crystals were not large enough for X-ray experiments, we expressed and purified OEC18 of maize by E. coli as a GST fusion protein. After cleavage of the protein with thrombin, we obtained some microcrystals under several conditions. We will optimize the crystallization conditions to obtain X-ray quality crystals. In addition, we will report the purification and crystallization of OEC33 from spinach.
