title: Structure of the oxygen evolving complex of Photosystem II at room temperature.
abstract: The functional structure of the Oxygen Evolving Complex, the Mn4Ca cluster of Photosystem II, a critical component of natural photosynthesis, was analyzed at room temperature by EXAFS. An experimental improvement in the form of a spinning sample holder allowed us to efficiently counteract the severe X-ray damage sensitivity of Photosystem II to obtain high quality data subsequently used for a systematic evaluation of atomistic S1 state models. We investigated the accuracy of models collected by both conventional and femtosecond XRD at 1.9 and 1.95 Å resolution, respectively, as well as DFT-based models, to determine the structure most representative of experimental data. Additionally, room temperature EXAFS results do not show a visible reduction in the intensity of the k-space oscillations, supporting a rigid structure of the Mn4Ca cluster at room temperature.
authors.affiliation: Department of Physics and Astronomy, Purdue University , 525 Northwestern Avenue, West Lafayette, Indiana 47907, United States.
authors.forename: Katherine M
authors.initials: KM
authors.lastname: Davis
authors.forename: Yulia N
authors.initials: YN
authors.lastname: Pushkar
mesh_terms: D003198:Computer Simulation; D005583:Fourier Analysis; D008956:Models, Chemical; D015394:Molecular Structure; D045332:Photosystem II Protein Complex / Q000737:chemistry*; D018724:Spinacia oleracea; D013696:Temperature; D056928:X-Ray Absorption Spectroscopy
chemical_list: D045332:Photosystem II Protein Complex