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Where Water Is Oxidized to Dioxygen: Structure of the Photosynthetic Mn4Ca Cluster
TLDR
Polarized extended x-ray absorption fine structure measurements on PSII single crystals constrain the Mn4Ca cluster geometry to a set of three similar high-resolution structures, unlike either the 3.0 or 3.5 angstrom–resolution x-rays or other previously proposed models. Expand
X-ray damage to the Mn4Ca complex in single crystals of photosystem II: a case study for metalloprotein crystallography.
TLDR
This case study shows that a careful evaluation of the structural intactness of the active site(s) by spectroscopic techniques can validate structures derived from crystallography and that it can be a valuable complementary method before structure-function correlations of metalloproteins can be made on the basis of high-resolution x-ray crystal structures. Expand
Structural changes in the Mn4Ca cluster and the mechanism of photosynthetic water splitting
TLDR
The results show that Ca is not just a spectator atom involved in providing a structural framework, but is actively involved in the mechanism of water oxidation and represents a rare example of a catalytically active Ca cofactor. Expand
Simultaneous Femtosecond X-ray Spectroscopy and Diffraction of Photosystem II at Room Temperature
TLDR
This simultaneous XRD-XES study shows that the PS II crystals are intact during measurements at the LCLS, not only with respect to the structure of PS II, but also with regard to the electronic structure of the highly radiation-sensitive Mn4CaO5 cluster, opening new directions for future dynamics studies. Expand
Accurate macromolecular structures using minimal measurements from X-ray free-electron lasers
TLDR
A computational approach designed to extract meaningful high-resolution signals from fewer diffraction measurements is presented. Expand
Structure and valency of a cobalt-phosphate water oxidation catalyst determined by in situ X-ray spectroscopy.
TLDR
A model is proposed wherein the Co oxo/hydroxo clusters of Co-Pi are composed of edge-sharing CoO(6) octahedra, the structural motif found in cobaltates, theStructural parameters extracted from fits to the EXAFS data of co-Pi with two different thicknesses are proposed and comparisons withEXAFS spectra of Co oxide compounds are compared. Expand
In situ X-ray absorption spectroscopy investigation of a bifunctional manganese oxide catalyst with high activity for electrochemical water oxidation and oxygen reduction.
TLDR
In situ XAS measurements on a bifunctional manganese oxide catalyst with high electrochemical activity for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) demonstrate that the OER activity scales with film thickness, which suggests that the films have porous structure, which does not restrict electrocatalysis to the top geometric layer of the film. Expand
Nanoflow electrospinning serial femtosecond crystallography.
TLDR
An electrospun liquid microjet has been developed that delivers protein microcrystal suspensions at flow rates of 0.14-3.1 µl min(-1) to perform serial femtosecond crystallography (SFX) studies with X-ray lasers, extending SFX to biological samples that necessitate minimal sample consumption. Expand
High-resolution Mn EXAFS of the oxygen-evolving complex in photosystem II: structural implications for the Mn4Ca cluster.
TLDR
High-resolution EXAFS method data is presented that shows three short Mn-Mn distances between 2.7 and 2.8 A and, hence, the presence of three di-mu-oxo-bridged units in the Mn4Ca cluster, imposing clear limitations on the proposed structures based on spectroscopic and diffraction data and provides input for refining such structures. Expand
X-Ray spectroscopy of the photosynthetic oxygen-evolving complex.
TLDR
X-ray spectroscopy is particularly useful because it can reveal important structural features of the complex with high accuracy and identify the participation of Mn in the redox chemistry. Expand
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