Ifuku Kentaro, Nakatsu Toru, Kato Hiroaki, Sato Fumihiko
Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kitashirakawa, Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan.
Acta Crystallogr D Biol Crystallogr. 2003 Aug;59(Pt 8):1462-3. doi: 10.1107/s0907444903011004. Epub 2003 Jul 23.
The extrinsic 23 kDa protein in the oxygen-evolving complex (OEC23 or PsbP) of photosystem II (PS II) helps to retain calcium and chloride ions, which are essential cofactors for the photosynthetic evolution of oxygen. OEC23 is found in the PS II complex from higher plants and green algae, but not in that from cyanobacteria or other ancestral photosynthetic organisms. In order to elucidate the three-dimensional structure and its molecular evolution, OEC23 was crystallized by the hanging-drop vapour-diffusion technique with PEG 4000 as a precipitant. Diffraction data to a resolution of 2.0 A were collected from a native crystal belonging to space group P2(1)2(1)2, with unit-cell parameters a = 91.36, b = 74.15, c = 52.16 A.
光系统II（PS II）放氧复合体中的外在23 kDa蛋白（OEC23或PsbP）有助于保留钙离子和氯离子，它们是光合放氧过程中必不可少的辅助因子。OEC23存在于高等植物和绿藻的PS II复合体中，但不存在于蓝细菌或其他原始光合生物的PS II复合体中。为了阐明其三维结构及其分子进化，采用悬滴气相扩散技术，以聚乙二醇4000作为沉淀剂，使OEC23结晶。从属于空间群P2(1)2(1)2的天然晶体收集到分辨率为2.0 Å的衍射数据，晶胞参数a = 91.36，b = 74.15，c = 52.16 Å。
