Deisenhofer J, Epp O, Sinning I, Michel H
Max-Planck-Institut für Biochemie, Martinsried, F.R.G.
J Mol Biol. 1995 Feb 24;246(3):429-57. doi: 10.1006/jmbi.1994.0097.
The atomic model of the photosynthetic reaction centre from the purple bacterium Rhodopseudomonas viridis has been refined to an R-value of 0.193 at 2.3 A resolution. The refined model contains 10,288 non-hydrogen atoms; 10,045 of these have well defined electron density. A Luzzati-plot indicates an average co-ordinate error of 0.26 A. During refinement, the positions of a partially ordered carotenoid, a unibiquinone in the partially occupied QB site, a detergent molecule, seven putative sulphate ions, and 201 water molecules were found. More than half of these waters are bound at interfaces between protein subunits and therefore contribute significantly to subunit interactions. Water molecules also play important structural and probably functional roles in the environment of some of the cofactors. Two water molecules form hydrogen bonds to the accessory bacteriochlorophylls and to the protein in the vicinity of the special pair of bacteriophylls, the primary electron donor. A group of about 10 water molecules is bound near the binding site of the secondary quinone QB. These waters are likely to participate in the transfer of protons to the doubly reduced QB.
来自绿脓杆菌（Rhodopseudomonas viridis）的光合反应中心的原子模型已在2.3埃分辨率下精修至R值为0.193。精修后的模型包含10288个非氢原子；其中10045个具有明确的电子密度。Luzzati图表明平均坐标误差为0.26埃。在精修过程中，发现了一个部分有序的类胡萝卜素、部分占据的QB位点中的一个泛醌、一个去污剂分子、七个假定的硫酸根离子和201个水分子的位置。这些水分子中一半以上结合在蛋白质亚基之间的界面处，因此对亚基相互作用有显著贡献。水分子在一些辅因子的环境中也起着重要的结构作用，可能还有功能作用。两个水分子与辅助细菌叶绿素以及在特殊对细菌叶绿素（初级电子供体）附近的蛋白质形成氢键。一组约10个水分子结合在次级醌QB的结合位点附近。这些水分子可能参与质子向双还原的QB的转移。
