scholarly journals A simple pressure-assisted method for MicroED specimen preparation

2021 ◽  
Author(s):  
Jingjing Zhao ◽  
Hongyi Xu ◽  
Hugo Lebrette ◽  
Marta Carroni ◽  
Helena Taberman ◽  
...  
Keyword(s):  
High Viscosity ◽  
Specimen Preparation ◽  
Universal Method ◽  
X Ray Diffraction ◽  
Simple Method ◽  
X Ray ◽  
Wide Range ◽  
Major Bottleneck ◽  
Crystal Electron

Abstract Micro-crystal electron diffraction (MicroED) has shown great potential for structure determination of macromolecular crystals too small for X-ray diffraction. However, specimen preparation remains a major bottleneck. Here, we report a simple method for preparing MicroED specimens, named Preassis, in which excess liquid is removed through an EM grid with the assistance of pressure. We show the ice thicknesses can be controlled by tuning the pressure in combination with EM grids with appropriate hole sizes. Importantly, Preassis can handle a wide range of protein crystals grown in various buffer conditions including those with high viscosity, as well as samples with low crystal contents. Preassis is a simple and universal method for MicroED specimen preparation, and will significantly broaden the applications of MicroED.

scholarly journals A simple pressure-assisted method for MicroED specimen preparation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jingjing Zhao ◽  
Hongyi Xu ◽  
Hugo Lebrette ◽  
Marta Carroni ◽  
Helena Taberman ◽  
...  
Keyword(s):  
High Viscosity ◽  
Specimen Preparation ◽  
Universal Method ◽  
X Ray Diffraction ◽  
Simple Method ◽  
X Ray ◽  
Wide Range ◽  
Major Bottleneck ◽  
Crystal Electron

AbstractMicro-crystal electron diffraction (MicroED) has shown great potential for structure determination of macromolecular crystals too small for X-ray diffraction. However, specimen preparation remains a major bottleneck. Here, we report a simple method for preparing MicroED specimens, named Preassis, in which excess liquid is removed through an EM grid with the assistance of pressure. We show the ice thicknesses can be controlled by tuning the pressure in combination with EM grids with appropriate carbon hole sizes. Importantly, Preassis can handle a wide range of protein crystals grown in various buffer conditions including those with high viscosity, as well as samples with low crystal concentrations. Preassis is a simple and universal method for MicroED specimen preparation, and will significantly broaden the applications of MicroED.

The petrology of the Mount Padbury mesosiderite and its achondrite enclaves

1966 ◽  
Vol 36 (276) ◽  
pp. 1029-1060 ◽  
Author(s):  
G. J. H. McCall
Keyword(s):  
Microscopic Analysis ◽  
Host Material ◽  
Refractive Indices ◽  
X Ray Diffraction ◽  
Thin Sections ◽  
X Ray ◽  
Wide Range ◽  
Varied Range ◽  
Optical Determination

SummaryThe petrography of the Mount Padbury meteorite, previously briefly recorded, is described in some detail. Both the metalliferous host material of the mesosiderite and the varied range of silicate-rich, virtually metal-free enclaves (including both familiar achondrite material and unfamiliar achondrite material) are described. Eucrite, brecciated eucrite, and a peculiar ‘shocked’ form of eucrite (resembling some terrestrial flaser-gabbros) are the calcium-rich achondrite types represented; hypersthene achondrite (including typical diogenite material and unfamiliar material) and olivine achondrite (granular aggregates of olivine not entirely similar to the unique chassignite and single crystals up to 4 in. in length) are the calcium-poor achondrite types represented. The eucrite displays more or less uniform mineralogy, but the mineral constituents are present in varying proportions, and there is a wide range of textural variations recognized. The silicate grain fragments enclosed in the metallic reticulation to form the mesosiderite host material are, significantly, entirely of minerals seen within the achondrite enclaves—plagioclase, hypersthene, pigeonite, olivine, and tridymite.These results include microscopic analysis of thin sections and polished sections, X-ray diffraction studies, optical determination of refractive indices using mineral grain mounts, and chemical analyses.The wider implications of this new and unique meteorite find are briefly considered.

LauePt, a graphical-user-interface program for simulating and analyzing white-beam X-ray diffraction Laue patterns

2010 ◽  
Vol 43 (4) ◽  
pp. 926-928 ◽  
Author(s):  
X. R. Huang
Keyword(s):  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Crystallography ◽  
White Beam ◽  
Diffraction Geometry ◽  
Wide Range ◽  
User Friendly ◽  
Beam Diffraction ◽  
Laue Method

LauePtis a robust and extremely easy-to-use Windows application for accurately simulating, indexing and analyzing white-beam X-ray diffraction Laue patterns of any crystals under arbitrary diffraction geometry. This program has a user-friendly graphic interface and can be conveniently used by nonspecialists with little X-ray diffraction or crystallography knowledge. Its wide range of applications include (1) determination of single-crystal orientation with the Laue method, (2) white-beam topography, (3) white-beam microdiffraction, (4) X-ray studies of twinning, domains and heterostructures, (5) verification or determination of crystal structures from white-beam diffraction, and (6) teaching of X-ray crystallography.

Quantitative X-Ray Structure Determination of Superlattices and Interfaces

1991 ◽  
Vol 229 ◽  
Author(s):  
Ivan K. Schuller ◽  
Eric E. Fullerton ◽  
H. Vanderstraeten ◽  
Y. Bruynseraede
Keyword(s):  
General Procedure ◽  
Structural Refinement ◽  
X Ray Diffraction ◽  
Diffraction Profile ◽  
X Ray ◽  
Superlattice Structure ◽  
Wide Range ◽  
Fitting Algorithm ◽  
Superlattice Structures

AbstractWe present a general procedure for quantitative structural refinement of superlattice structures. To analyze a wide range of superlattices, we have derived a general kinematical diffraction formula that includes random, continuous and discrete fluctuations from the average structure. By implementing a non-linear fitting algorithm to fit the entire x-ray diffraction profile, refined parameters that describe the average superlattice structure, and deviations from this average are obtained. The structural refinement procedure is applied to a crystalline/crystalline Mo/Ni superlattices and crystalline/amorphous Pb/Ge superlattices. Roughness introduced artificially during growth in Mo/Ni superlattices is shown to be accurately reproduced by the refinement.

scholarly journals A simple pressure-assisted method for cryo-EM specimen preparation

2019 ◽  
Author(s):  
J. Zhao ◽  
H. Xu ◽  
M. Carroni ◽  
H. Lebrette ◽  
K. Wallden ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Pressure Gradient ◽  
Structural Biology ◽  
Specimen Preparation ◽  
Single Particles ◽  
Simple Method ◽  
Cryo Electron Microscopy ◽  
Low Concentrations ◽  
Wide Range ◽  
Major Bottleneck

AbstractCryo-electron microscopy (cryo-EM) has made great impacts on structural biology. However, specimen preparation remains a major bottleneck. Here, we report a simple method for preparing cryo-EM specimens, named Preassis, in which the excess liquid is removed by introducing a pressure gradient through the EM grid. We show the unique advantages of Preassis in handling samples with low concentrations of protein single particles and micro-crystals in a wide range of buffer conditions.

Diameter Determination of Frozen-Hydrated Virions Using Polyoma Virus as a Calibration Standard

1988 ◽  
Vol 46 ◽  
pp. 166-167
Author(s):  
N. H. Olson ◽  
T. S. Baker
Keyword(s):  
Accurate Determination ◽  
Carbon Substrate ◽  
Specimen Preparation ◽  
X Ray Diffraction ◽  
Polystyrene Spheres ◽  
X Ray ◽  
Negative Stain ◽  
Highly Sensitive ◽  
Particle Images

Accurate determination of particle dimensions requires both a reliable measure of the instrumental magnification and reproducible, non-distorting specimen preparation procedures. Typical calibration standards for measuring microscope magnification include replica gratings, polystyrene spheres, and negatively-stained catalase crystals. Polystyrene spheres and catalase crystals may be used as internal standards but both are highly sensitive to beam damage. Calibrations with replica gratings are subject to greater inaccuracies at magnifications exceeding 10,000-20,000 X. Furthermore, for negatively-stained biological specimens, the object of interest as well as the standard (e.g. catalase) are susceptible to significant distortions produced when the stained sample dries on the grid. The stain itself also moves during the initial stages of irradiation.1.2Large discrepancies are often found between diameter measurements from particle images with circular profiles (e.g. spherical viruses) made in the microscope and from those measurements determined by x-ray solution scattering or other x-ray diffraction techniques. Measurements from virions embedded in negative-stain, suspended over holes in a carbon substrate, are typically much lower than the corresponding measurements by x-ray techniques, reflecting a probable shrinkage of virions in the stain.

Determination of Thermal Expansion by High-Temperature X-Ray Diffraction

1961 ◽  
Vol 5 ◽  
pp. 238-243 ◽  
Author(s):  
Dale A. Vaughan ◽  
Charles M. Schwartz
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Ceramic Materials ◽  
Lattice Parameter ◽  
Specimen Preparation ◽  
X Ray Diffraction ◽  
X Ray ◽  
And Control ◽  
Measurement And Control

AbstractTwo high-temperature X-ray diffraction cameras are described which have been employed at Battelle to determine thermal expansion of metals and ceramic materials. Specimen preparation and temperature measurement and control are described. Lattice-parameter data vs. temperature are presented for uranium, uranium dioxide, and magnesium oxide.

scholarly journals A Simple Method for the Determination of Lattice Parameters from Powder X-ray Diffraction Data

1989 ◽  
Vol 30 (7) ◽  
pp. 474-479 ◽  
Author(s):  
D. S. Tsai ◽  
T. S. Chin ◽  
S. E. Hsu ◽  
M. P. Hung
Keyword(s):  
Diffraction Data ◽  
Lattice Parameters ◽  
X Ray Diffraction ◽  
Simple Method ◽  
X Ray

Determination of the 'true' width of the actin filament

1983 ◽  
Vol 41 ◽  
pp. 534-535
Author(s):  
Walter E. Fowler ◽  
Ueli Aebi
Keyword(s):  
Electron Microscopy ◽  
Actin Filament ◽  
Specimen Preparation ◽  
Molecular Models ◽  
X Ray Diffraction ◽  
Preparation Methods ◽  
Average Width ◽  
X Ray ◽  
Lower Limits

Although the structure of the actin filament has been studied extensively both, by X-ray diffraction analysis and by electron microscopy and structure reconstruction, molecular models of actin have been obtained only recently. However none of the crystalline forms used in these latter studies are made directly from filaments. Since the resolution of current filament models is insufficient to allow unambiguous tracing of the actin subunits within them [e.g.2], the orientation of molecular models within such filament models is speculative. A primary constraint on the overall orientation of the elongated and polar actin subunit model within the actin filament is the 'true' width of the filament: reported values as obtained by electron microscopy range from 6 to 8nm for negatively stained specimens and to 9.5nm or more for rotary shadowed filaments [reviewed in 3]. Furthermore, X-ray solution scattering of actin filaments has revealed an average width of 7nm. Using a variety of different specimen preparation methods, we have endeavoured to set realistic upper and lower limits for this crucial parameter.

scholarly journals Crystallization and X-ray structure determination of a thermoalkalophilic lipase fromGeobacillusSBS-4S

2013 ◽  
Vol 69 (4) ◽  
pp. 355-357
Author(s):  
Muhammad Tayyab ◽  
Naeem Rashid ◽  
Clement Angkawidjaja ◽  
Shigenori Kanaya ◽  
Muhammad Akhtar
Keyword(s):  
Diffusion Method ◽  
Molecular Replacement ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Replacement Method ◽  
Wide Range ◽  
Molecular Replacement Method

A thermoalkalophilic lipase (LIPSBS) from the newly isolatedGeobacillusstrain SBS-4S which hydrolyzes a wide range of fatty acids has been characterized. In the present study, the crystallization of purified LIPSBSusing the sitting-drop vapour-diffusion method and its X-ray diffraction studies are described. The crystals belonged to the orthorhombic space groupP212121, with unit-cell parametersa= 55.13,b= 71.75,c= 126.26 Å. The structure was determined at 1.6 Å resolution by the molecular-replacement method using the lipase fromG. stearothermophilusL1 as a model.

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