Krauss N, Schubert W D, Klukas O, Fromme P, Witt H T, Saenger W
Institut für Kristallographie, Freie Universität Berlin, Germany.
Nat Struct Biol. 1996 Nov;3(11):965-73. doi: 10.1038/nsb1196-965.
The 4 A X-ray structure model of trimeric photosystem I of the cyanobacterium Synechococcus elongatus reveals 31 transmembrane, nine surface and three stromal alpha-helices per monomer, assigned to the 11 protein subunits: PsaA and PsaB are related by a pseudo two-fold axis normal to the membrane plane, along which the electron transfer pigments are arranged. 65 antenna chlorophyll a (Chl a) molecules separated by < or = 16 A form an oval, clustered net continuous with the electron transfer chain through the second and third Chl a pairs of the electron transfer system. This suggests a dual role for these Chl a both in excitation energy and electron transfer. The architecture of the protein core indicates quinone and iron-sulphur type reaction centres to have a common ancestor.
细长聚球蓝细菌三聚体光系统I的4 Å X射线结构模型显示，每个单体有31个跨膜α螺旋、9个表面α螺旋和3个基质α螺旋，它们分属于11个蛋白质亚基：PsaA和PsaB通过垂直于膜平面的假二重轴对称，沿此轴排列着电子传递色素。65个天线叶绿素a（Chl a）分子以小于或等于16 Å的间距隔开，形成一个椭圆形的簇状网络，通过电子传递系统的第二和第三对Chl a与电子传递链相连。这表明这些Chl a在激发能和电子传递中都具有双重作用。蛋白质核心结构表明醌型和铁硫型反应中心有共同的祖先。
