scholarly journals Ultra-high resolution structure of endopolygalacturonase determined by X-ray and neutron diffraction

2008 ◽  
Vol 64 (a1) ◽  
pp. C368-C369
Author(s):  
T. Shimizu ◽  
T. Nakatsu ◽  
N. Shimizu ◽  
M. Sato ◽  
K. Kurihara ◽  
...  
Keyword(s):  
High Resolution ◽  
Neutron Diffraction ◽  
X Ray ◽  
High Resolution Structure ◽  
Resolution Structure

Study of Diffuse Scattering by Means of High Resolution Structure Images

1976 ◽  
Vol 34 ◽  
pp. 476-477
Author(s):  
Sumio Iijima ◽  
G. R. Anstis
Keyword(s):  
High Resolution ◽  
Neutron Diffraction ◽  
Diffuse Scattering ◽  
Reciprocal Space ◽  
The Other ◽  
X Ray ◽  
Actual Model ◽  
High Resolution Structure ◽  
Made In ◽  
Resolution Structure

Disorders in crystals with relatively simple structures which gave diffuse scattering have been extensively studied by X-ray or neutron diffraction methods. All these investigations were based on traditional diffraction methods and observations were made in reciprocal space (note observable diffraction intensities can be considered only in terms of interatomic vectors) and therefore the results obtained there leaves considerable ambiguity, particularly when we try to derive an actual model of the disordered crystals. A solution of this problem will be given only by knowing all atom positions in an assembly of atoms and for this case the observable diffracted intensity is given bywhere (xi,yi) and (xj,yj) represent position vectors of the i th and j th atoms with scattering factors fi and fj from an arbitrary origin. On the other hand, a crystal containing imperfections can be defined by

scholarly journals High-resolution structure of the photosynthetic Mn 4 Ca catalyst from X-ray spectroscopy

2007 ◽  
Vol 363 (1494) ◽  
pp. 1139-1147 ◽  
Author(s):  
Junko Yano ◽  
Jan Kern ◽  
Yulia Pushkar ◽  
Kenneth Sauer ◽  
Pieter Glatzel ◽  
...  
Keyword(s):  
High Resolution ◽  
Spectroscopic Techniques ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Resolution Structure ◽  
Resonant Raman ◽  
X Ray Absorption ◽  
Water Oxidizing Complex ◽  
S States ◽  
Resolution Structure

The application of high-resolution X-ray spectroscopy methods to study the photosynthetic water oxidizing complex, which contains a unique hetero-nuclear catalytic Mn 4 Ca cluster, is described. Issues of X-ray damage, especially at the metal sites in the Mn 4 Ca cluster, are discussed. The structure of the Mn 4 Ca catalyst at high resolution, which has so far eluded attempts of determination by X-ray diffraction, X-ray absorption fine structure (EXAFS) and other spectroscopic techniques, has been addressed using polarized EXAFS techniques applied to oriented photosystem II (PSII) membrane preparations and PSII single crystals. A review of how the resolution of traditional EXAFS techniques can be improved, using methods such as range-extended EXAFS, is presented, and the changes that occur in the structure of the cluster as it advances through the catalytic cycle are described. X-ray absorption and emission techniques (XANES and Kβ emission) have been used earlier to determine the oxidation states of the Mn 4 Ca cluster, and in this report we review the use of X-ray resonant Raman spectroscopy to understand the electronic structure of the Mn 4 Ca cluster as it cycles through the intermediate S-states.

Approaches to the High Resolution Structure of Periodic Membrane Proteins

1980 ◽  
Vol 38 ◽  
pp. 666-669
Author(s):  
J.W. Wiggins
Keyword(s):  
High Resolution ◽  
Membrane Proteins ◽  
Aqueous Media ◽  
Integral Membrane Proteins ◽  
X Ray Diffraction ◽  
Sequence Determination ◽  
X Ray ◽  
High Resolution Structure ◽  
Gain Access ◽  
Resolution Structure

Integral membrane proteins are particularly difficult to study at high resolution for several reasons. Amino acid sequence determination may be difficult because the fragmentation reagents cannot gain access to the required site, fragments are insoluble in aqueous media, or lipids are difficult to remove. X-ray diffraction studies cannot be undertaken without large enough crystals. Electron microscopy studies of the usual sort cannot be used because dehydration, negative staining, embedding, and other typical procedures are incompatible with the preservation and contrasting of the structure. Even determinations of molecular weight are made difficult by the presence of bound lipid and polysaccharide.

Efficient, high-throughput ligand incorporation into protein microcrystals by on-grid soaking

2020 ◽  
Author(s):  
Michael W. Martynowycz ◽  
Tamir Gonen
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Proteinase K ◽  
X Ray ◽  
X Ray Crystallography ◽  
High Resolution Structure ◽  
Efficient Uptake ◽  
Resolution Structure

AbstractA method for soaking ligands into protein microcrystals on TEM grids is presented. Every crystal on the grid is soaked simultaneously using only standard cryoEM vitrification equipment. The method is demonstrated using proteinase K microcrystals soaked with the 5-amino-2,4,6-triodoisophthalic acid (I3C) magic triangle. A soaked microcrystal is milled to a thickness of 200nm using a focused ion-beam, and microcrystal electron diffraction (MicroED) data are collected. A high-resolution structure of the protein with four ligands at high occupancy is determined. Compared to much larger crystals investigated by X-ray crystallography, both the number of ligands bound and their occupancy was higher in MicroED. These results indicate that soaking ligands into microcrystals in this way results in a more efficient uptake than in larger crystals that are typically used in drug discovery pipelines by X-ray crystallography.

scholarly journals Genuine open form of the pentameric ligand-gated ion channel GLIC

2015 ◽  
Vol 71 (3) ◽  
pp. 454-460 ◽  
Author(s):  
Zaineb Fourati ◽  
Ludovic Sauguet ◽  
Marc Delarue
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Conformational Changes ◽  
Computational Studies ◽  
Potential Influence ◽  
X Ray ◽  
Correct Assignment ◽  
High Resolution Structure ◽  
Fast Chemical ◽  
Resolution Structure

Pentameric ligand-gated ion channels (pLGICs) mediate fast chemical neurotransmission of nerve signalling in the central and peripheral nervous systems. GLIC is a bacterial homologue of eukaryotic pLGIC, the X-ray structure of which has been determined in three different conformations. GLIC is thus widely used as a model to study the activation and the allosteric transition of this family of receptors. The recently solved high-resolution structure of GLIC (2.4 Å resolution) in the active state revealed two bound acetate molecules in the extracellular domain (ECD). Here, it is shown that these two acetates exactly overlap with known sites of pharmacological importance in pLGICs, and their potential influence on the structure of the open state is studied in detail. Firstly, experimental evidence is presented for the correct assignment of these acetate molecules by using the anomalous dispersion signal of bromoacetate. Secondly, the crystal structure of GLIC in the absence of acetate was solved and it is shown that acetate binding induces local conformational changes that occur in strategic sites of the ECD. It is expected that this acetate-free structure will be useful in future computational studies of the gating transition in GLIC and other pLGICs.

scholarly journals Comparing the Folds of Prions and Other Pathogenic Amyloids

Pathogens ◽  
2018 ◽  
Vol 7 (2) ◽  
pp. 50 ◽  
Author(s):  
José Flores-Fernández ◽  
Vineet Rathod ◽  
Holger Wille
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Amyloid Β ◽  
Paired Helical Filaments ◽  
X Ray ◽  
Cryo Electron Microscopy ◽  
Incompatibility System ◽  
High Resolution Structure ◽  
Jakob Disease ◽  
Resolution Structure

Pathogenic amyloids are the main feature of several neurodegenerative disorders, such as Creutzfeldt–Jakob disease, Alzheimer’s disease, and Parkinson’s disease. High resolution structures of tau paired helical filaments (PHFs), amyloid-β(1-42) (Aβ(1-42)) fibrils, and α-synuclein fibrils were recently reported using cryo-electron microscopy. A high-resolution structure for the infectious prion protein, PrPSc, is not yet available due to its insolubility and its propensity to aggregate, but cryo-electron microscopy, X-ray fiber diffraction, and other approaches have defined the overall architecture of PrPSc as a 4-rung β-solenoid. Thus, the structure of PrPSc must have a high similarity to that of the fungal prion HET-s, which is part of the fungal heterokaryon incompatibility system and contains a 2-rung β-solenoid. This review compares the structures of tau PHFs, Aβ(1-42), and α-synuclein fibrils, where the β-strands of each molecule stack on top of each other in a parallel in-register arrangement, with the β-solenoid folds of HET-s and PrPSc.

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