High-resolution three-dimensional Coulomb potential map of PhoE porin

1992 ◽  
Vol 50 (1) ◽  
pp. 434-435
Author(s):  
Bing K. Jap ◽  
Thomas N. Earnest ◽  
Peter Walian ◽  
Kalle Gehring
Keyword(s):  
High Resolution ◽  
Three Dimensional ◽  
Data Set ◽  
Membrane Pore ◽  
3 Dimensional ◽  
Potential Map ◽  
High Resolution Images ◽  
Diffraction Patterns ◽  
Phoe Porin ◽  
Structural Architecture

PhoE porin is an outer membrane, pore-forming channel with selectivity for the transport of phosphate-containing compounds and negatively charged solutes. We have reconstituted this membrane protein with lipids to form highly coherent, 2-dimensional crystalline patches. Diffraction patterns and images of trehalose embedded crystalline patches were recorded using a JEOL 100B electron microscope, which is equipped with a field emission gun and a cold stage that was operated at about −120° C. A complete 3-dimensional (3-D) diffraction data set to a resolution of 2.8Å and a number of high resolution images at tilt angles ranging from 0 to 60 degrees were collected. A high resolution projection map at 3.5Å resolution and a 3-D map at 6Å , showing the detailed structural architecture of this protein, have been published.

Refinement of the three-dimensional structure of PhoE porin at 3.2Å resolution as determined by electron crystallography

1994 ◽  
Vol 52 ◽  
pp. 96-97
Author(s):  
Bing K. Jap ◽  
Peter Walian ◽  
Thomas Earnest
Keyword(s):  
High Resolution ◽  
Coulomb Potential ◽  
Molecular Model ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Phase Information ◽  
Electron Crystallography ◽  
Data Set ◽  
Crystallographic Symmetry ◽  
Phoe Porin

Density modification methods were used to improve the three-dimensional map of PhoE porin which has been obtained by electron crystallographic techniques. The electron crystallographic data set consists of diffraction amplitudes that extend to a resolution of∽ 2.8 Å and phase information derived from 22 tilted and 8 untilted images at 3.5 Å resolution. However the data set was restricted to tilt angles less than ∽ 60 degrees, and therefore there is a missing cone regionin our 3-D data set. Non-crystallographic symmetry averaging and solvent flattening techniques were used to improve and extend the phase information, allowing for the calculation of high resolution Coulomb potential maps of membrane-embedded PhoE. These maps were used as a basis for building a partial molecular model, which was subsequently used to supply phase information to be combined with the experimentally determined phases. The combined phases were then used to calculate improved maps. As the maps continue to improve, more of the backbone and some of the side chains were built into the maps.

Electron diffraction from anthracene

1996 ◽  
Vol 54 ◽  
pp. 688-689
Author(s):  
W. F. Tivol ◽  
J. H. Kim
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Room Temperature ◽  
Three Dimensional ◽  
Zone Axis ◽  
Data Set ◽  
High Resolution Data ◽  
Diffraction Patterns ◽  
Reduced Temperature ◽  
Resolution Data

Collection of a three-dimensional data set from anthracene illustrates some of the difficulties which can be encountered. Since the crystals are grown from solution their orientation is not certain, and the crystals are very bendy, so a range of orientations is encountered at a given tilt setting. Anthracene is moderately labile to irradiation, so care must be taken to avoid radiation damage during data collection. Anthracene will sublime at room temperature under vacuum, so the data must be collected at reduced temperature. Flat, well-ordered areas of the crystals are rare, so collection of high-resolution data is time-consuming. The thickness of the crystals is difficult to control, so finding areas which have minimal multiple scattering is also formidable.The structure of anthracene is already known, so simulations of the diffraction patterns along various zone axes can be made. Cerius 2.0® was used to produce simulated zone axis patterns for all combinations of indices whose absolute values were 3 or less. The preferred orientation for the untilted grid is [102]. Scans of several preparations resulted in patterns which matched the simulation for [102]. The angles for each of the Miller planes with respect to [102] were calculated from the formula given by Dorset.

Electron crystallographic determination of the 3-D structure of staurolite at atomic resolution

1991 ◽  
Vol 49 ◽  
pp. 540-541
Author(s):  
Kenneth H. Downing ◽  
Hu Meisheng ◽  
Hans-Rudolf Went ◽  
Michael A. O'Keefe
Keyword(s):  
High Resolution ◽  
Three Dimensional ◽  
High Resolution Electron Microscopy ◽  
Atomic Resolution ◽  
Dimensional Structure ◽  
Structure Information ◽  
Resolution Electron ◽  
Scattering Effects ◽  
High Resolution Images ◽  
Effects Of Radiation

With current advances in electron microscope design, high resolution electron microscopy has become routine, and point resolutions of better than 2Å have been obtained in images of many inorganic crystals. Although this resolution is sufficient to resolve interatomic spacings, interpretation generally requires comparison of experimental images with calculations. Since the images are two-dimensional representations of projections of the full three-dimensional structure, information is invariably lost in the overlapping images of atoms at various heights. The technique of electron crystallography, in which information from several views of a crystal is combined, has been developed to obtain three-dimensional information on proteins. The resolution in images of proteins is severely limited by effects of radiation damage. In principle, atomic-resolution, 3D reconstructions should be obtainable from specimens that are resistant to damage. The most serious problem would appear to be in obtaining high-resolution images from areas that are thin enough that dynamical scattering effects can be ignored.

Merging of electron-diffraction intensities acquired with a slow-scan CCD camera of crotoxin complex crystals to 3.5Å resolution

1994 ◽  
Vol 52 ◽  
pp. 104-105
Author(s):  
Jaap Brink ◽  
Wah Chiu
Keyword(s):  
Electron Diffraction ◽  
Ccd Camera ◽  
Crystal Thickness ◽  
Local Contrast ◽  
Camera Model ◽  
Data Set ◽  
3 Dimensional ◽  
Diffraction Mode ◽  
Diffraction Patterns ◽  
Complex Crystals

Crotoxin complex is the principal neurotoxin of the South American rattlesnake, Crotalus durissus terrificus and has a molecular weight of 24 kDa. The protein is a heterodimer with subunit A assigneda chaperone function. Subunit B carries the lethal activity, which is exerted on both sides ofthe neuro-muscular junction, and which is thought to involve binding to the acetylcholine receptor. Insight in crotoxin complex’ mode of action can be gained from a 3 Å resolution structure obtained by electron crystallography. This abstract communicates our progress in merging the electron diffraction amplitudes into a 3-dimensional (3D) intensity data set close to completion. Since the thickness of crotoxin complex crystals varies from one crystal to the other, we chose to collect tilt series of electron diffraction patterns after determining their thickness. Furthermore, by making use of the symmetry present in these tilt data, intensities collected only from similar crystals will be merged.Suitable crystals of glucose-embedded crotoxin complex were searched for in the defocussed diffraction mode with the goniometer tilted to 55° of higher in a JEOL4000 electron cryo-microscopc operated at 400 kV with the crystals kept at -120°C in a Gatan 626 cryo-holder. The crystal thickness was measured using the local contrast of the crystal relative to the supporting film from search-mode images acquired using a 1024 x 1024 slow-scan CCD camera (model 679, Gatan Inc.).

High-resolution transmission electron microscopic investigations of molybdenum thin films on faceted α-Al2O3

2005 ◽  
Vol 38 (2) ◽  
pp. 260-265 ◽  
Author(s):  
Leonore Wiehl ◽  
Jens Oster ◽  
Michael Huth
Keyword(s):  
High Resolution ◽  
Three Dimensional ◽  
Epitaxial Relationship ◽  
Electron Microscopic ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
High Resolution Images ◽  
Α Al2o3 ◽  
Relationship Of

Epitaxially grown Mo films on a faceted corundum (α-Al2O3)mplane were investigated by transmission electron microscopy. Low- and high-resolution images were taken from a cross-section specimen cut perpendicular to the facets. It was possible to identify unambiguously the crystallographic orientation of these facets and explain the considerable deviation (∼10°) of the experimental interfacet angle, as measured with atomic force microscopy (AFM), from the expected value. For the first time, proof is given for a smooth \{10\bar{1}1\} facet and a curvy facet with orientation near to \{10\bar{1}\bar{2}\}. Moreover, the three-dimensional epitaxial relationship of an Mo film on a faceted corundummsurface was determined.

Atomic structure of YB56 studied by digital high-resolution electron microscopy and electron diffraction

2001 ◽  
Vol 16 (1) ◽  
pp. 101-107 ◽  
Author(s):  
Takeo Oku ◽  
Jan-Olov Bovin ◽  
Iwami Higashi ◽  
Takaho Tanaka ◽  
Yoshio Ishizawa
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction ◽  
High Resolution Electron Microscopy ◽  
Charge Coupled Device ◽  
X Ray ◽  
Resolution Electron ◽  
High Resolution Images ◽  
Diffraction Patterns ◽  
Simulated Images

Atomic positions for Y atoms were determined by using high-resolution electron microscopy and electron diffraction. A slow-scan charge-coupled device camera which had high linearity and electron sensitivity was used to record high-resolution images and electron diffraction patterns digitally. Crystallographic image processing was applied for image analysis, which provided more accurate, averaged Y atom positions. In addition, atomic disordering positions in YB56 were detected from the differential images between observed and simulated images based on x-ray data, which were B24 clusters around the Y-holes. The present work indicates that the structure analysis combined with digital high-resolution electron microscopy, electron diffraction, and differential images is useful for the evaluation of atomic positions and disordering in the boron-based crystals.

High-resolution three-dimensional T2-weighted sequence for neuronavigation: a new setup and clinical trial

2005 ◽  
Vol 102 (4) ◽  
pp. 658-663 ◽  
Author(s):  
Jan Gralla ◽  
Raphael Guzman ◽  
Caspar Brekenfeld ◽  
Luca Remonda ◽  
Claus Kiefer
Keyword(s):  
Clinical Trial ◽  
High Resolution ◽  
Clinical Application ◽  
Three Dimensional ◽  
Whole Body ◽  
Low Grade ◽  
Data Set ◽  
Content Type ◽  
Image Guided ◽  
Fine Print

Object. Conventional imaging for neuronavigation is performed using high-resolution computerized tomography (CT) scanning or a T1-weighted isovoxel magnetic resonance (MR) sequence. The extension of some lesions, however, is depicted much better on T2-weighted MR images. A possible fusion process used to match low-resolution T2-weighted MR image set with a referenced CT or T1-weighted data set leads to poor resolution in the three-dimensional (3D) reconstruction and decreases accuracy, which is unacceptable for neuronavigation. The object of this work was to develop a 3D T2-weighted isovoxel sequence (3D turbo—spin echo [TSE]) for image-guided neuronavigation of the whole brain and to evaluate its clinical application. Methods. The authors performed a phantom study and a clinical trial on a newly developed T2-weighted isovoxel sequence, 3D TSE, for image-guided neuronavigation using a common 1.5-tesla MR imager (Siemens Sonata whole-body imager). The accuracy study and intraoperative image guidance were performed with the aid of the pointer-based Medtronic Stealth Station Treon. The 3D TSE data set was easily applied to the navigational setup and demonstrated a high registration accuracy during the experimental trial and during an initial prospective clinical trial in 25 patients. The sequence displayed common disposable skin fiducial markers and provided convincing delineation of lesions that appear hyperintense on T2-weighted images such as low-grade gliomas and cavernomas in its clinical application. Conclusions. Three-dimensional TSE imaging broadens the spectrum of navigational and intraoperative data sets, especially for lesions that appear hyperintense on T2-weighted images. The accuracy of its registration is very reliable and it enables high-resolution reconstruction in any orientation, maintaining the advantages of image-guided surgery.

HRSC-A data: a new high-resolution data set with multipurpose applications in physical geography

2007 ◽  
Vol 31 (2) ◽  
pp. 179-197 ◽  
Author(s):  
J.-C. Otto ◽  
K. Kleinod ◽  
O. König ◽  
M. Krautblatter ◽  
M. Nyenhuis ◽  
...  
Keyword(s):  
High Resolution ◽  
Land Surface ◽  
Research Training ◽  
Spatial Scales ◽  
Three Dimensional ◽  
Physical Geography ◽  
Vegetation Monitoring ◽  
Data Set ◽  
High Resolution Data ◽  
Resolution Data

The analysis and interpretation of remote sensing data facilitates investigation of land surface complexity on large spatial scales. We introduce here a geometrically high-resolution data set provided by the airborne High Resolution Stereo Camera (HRSC-A). The sensor records digital multispectral and panchromatic stereo bands from which a very high-resolution ground elevation model can be produced. After introducing the basic principles of the HRSC technique and data, applications of HRSC data within the multidisciplinary Research Training Group 437 are presented. Applications include geomorphologic mapping, geomorphometric analysis, mapping of surficial grain-size distribution, rock glacier kinematic analysis, vegetation monitoring and three-dimensional landform visualization. A final evaluation of the HRSC data based on three years of multipurpose usage concludes this presentation. A combination of image and elevation data opens up various possibilities for visualization and three-dimensional analysis of the land surface, especially in geomorphology. Additionally, the multispectral imagery of the HRSC data has potential for land cover mapping and vegetation monitoring. We consider HRSC data a valuable source of high-resolution terrain information with high applicability in physical geography and earth system science.

Electron Crystallographic Determination of the Structure of Bacteriorhodopsin

1990 ◽  
Vol 48 (1) ◽  
pp. 90-91
Author(s):  
R. Henderson ◽  
J.M. Baldwin ◽  
T.A. Ceska ◽  
E. Beckman ◽  
F. Zemlin ◽  
...  
Keyword(s):  
High Resolution ◽  
Proton Pump ◽  
Three Dimensional ◽  
Atomic Resolution ◽  
Two Dimensional ◽  
New Methods ◽  
Density Map ◽  
Diffraction Patterns

The light driven proton pump bacteriorhodopsin (bR) occurs naturally as two-dimensional crystals. A three-dimensional density map of the structure, at near atomic resolution, has been obtained by studying the crystals using electron cryo-microscopy to obtain diffraction patterns and high resolution micrographs (1).New methods have been developed for analysing micrographs from tilted specimens, incorporating the methods previously developed for untilted specimens that enable large areas to be analysed and corrected for distortions. Data from 72 images, from both tilted and untilted specimens, have been analysed to produce the phases of 2700 independent Fourier components of the structure. The amplitudes of these components have been accurately measured from 150 diffraction patterns. Together, these data represent about half of the full three-dimensional transform to 3.5 Å. The distribution of the data which is included in the map is shown in fig. 1. For specimen tilts up to around 20° the data is essentially complete. For higher tilts the data is more sparsely sampled, and is at present about half complete.

Analysis of Image Contrast in High-Resolution Images of n-Paraffin Recorded at 400 kV and -167°C

1990 ◽  
Vol 48 (1) ◽  
pp. 86-87
Author(s):  
J. Brink ◽  
W. Chiu
Keyword(s):  
High Resolution ◽  
Image Contrast ◽  
Depth Of Field ◽  
Spot Scanning ◽  
Structure Factors ◽  
Ewald Sphere ◽  
High Resolution Images ◽  
Resolution Imaging ◽  
Diffraction Patterns ◽  
Envelope Functions

Images of radiation-sensitive two-dimensional crystals quite often fail to display the same resolution visible in electron diffraction patterns of these crystals. It is now generally accepted that besides the microscope's envelope functions, radiation damage and the MTF of the film and cryo-holder, beam-induced specimen motion is a major contrast degrading factor. Minimization of this movement proved possible through use of narrow electron beams, i.e. in spot-scanning. Routine high resolution imaging, however, remains a difficult task. We have investigated the possibilities of enhancing the effeciency this goal by using 400 keV electrons. Based upon overall less attenuation from the envelope functions at 400 kV, structure factors at around 3Å resolution would show amplitudes easily twice as large as compared to 100 kV. Further, at 400 kV inelastic scattering would be reduced relative to 100 kV. Moreover, it has been suggested that image contrast would increase roughly proportional to β. Additional advantages concerning for instance Ewald sphere curvature and depth of field have been put forward in Chiu et al.

Sign in / Sign up

Export Citation Format

Share Document