Two-Dimensional Crystallization of Tetanus Toxin

1985 ◽  
Vol 43 ◽  
pp. 528-529
Author(s):  
Jeffry A. Reidler ◽  
John P. Robinson
Keyword(s):  
Electron Microscopy ◽  
Tetanus Toxin ◽  
Structural Information ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Membrane Interface ◽  
3D Reconstructions ◽  
Cellular Receptors ◽  
Computer Reconstruction ◽  
2D Crystals

We have prepared two-dimensional (2D) crystals of tetanus toxin using procedures developed by Uzgiris and Kornberg for the directed production of 2D crystals of monoclonal antibodies at an antigen-phospholipid monolayer interface. The tetanus toxin crystals were formed using a small mole fraction of the natural receptor, GT1, incorporated into phosphatidyl choline monolayers. The crystals formed at low concentration overnight. Two dimensional crystals of this type are particularly useful for structure determination using electron microscopy and computer image refinement. Three dimensional (3D) structural information can be derived from these crystals by computer reconstruction of photographs of toxin crystals taken at different tilt angles. Such 3D reconstructions may help elucidate the mechanism of entry of the enzymatic subunit of toxins into cells, particularly since these crystals form directly on a membrane interface at similar concentrations of ganglioside GT1 to the natural cellular receptors.

scholarly journals Cephalometric measurements from 3D reconstructed images compared with conventional 2D images

2011 ◽  
Vol 81 (5) ◽  
pp. 856-864 ◽  
Author(s):  
Natalia Zamora ◽  
Jose M. Llamas ◽  
Rosa Cibrián ◽  
Jose L. Gandia ◽  
Vanessa Paredes
Keyword(s):  
Three Dimensional ◽  
Cone Beam ◽  
Two Dimensional ◽  
Linear Measurements ◽  
3D Reconstructions ◽  
Software Packages ◽  
Mandibular Plane ◽  
Different Types ◽  
Cephalometric Measurements ◽  
2D Images

Abstract Objective: To assess whether the values of different measurements taken on three-dimensional (3D) reconstructions from cone-beam computed tomography (CBCT) are comparable with those taken on two-dimensional (2D) images from conventional lateral cephalometric radiographs (LCRs) and to examine if there are differences between the different types of CBCT software when taking those measurements. Material and Methods: Eight patients were selected who had both an LRC and a CBCT. The 3D reconstructions of each patient in the CBCT were evaluated using two different software packages, NemoCeph 3D and InVivo5. An observer took 10 angular and 3 linear measurements on each of the three types of record on two different occasions. Results: Intraobserver reliability was high except for the mandibular plane and facial cone (from the LCR), the Na-Ans distance (using NemoCeph 3D), and facial cone and the Ans-Me distance (using InVivo5). No statistically significant differences were found for the angular and linear measurements between the LCRs and the CBCTs for any measurement, and the correlation levels were high for all measurements. Conclusion: No statistically significant differences were found between the angular and linear measurements taken with the LCR and those taken with the CBCT. Neither were there any statistically significant differences between the angular or linear measurements using the two CBCT software packages.

Crystallization Time Dependence of Nanohybrid Shish-Kebab Structure in HDPE/PA66 Nanofibers Composites via Solution Crystallization

2011 ◽  
Vol 110-116 ◽  
pp. 3786-3790
Author(s):  
Wen Juan Han ◽  
Guo Qiang Zheng ◽  
Yan Yan Liang ◽  
Chun Tai Liu ◽  
Chang Yu Shen
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Time Dependence ◽  
Isothermal Crystallization ◽  
Three Dimensional ◽  
Crystallization Time ◽  
Two Dimensional ◽  
Solution Crystallization ◽  
Dimensional Growth ◽  
Scanning Electron

In this study, PA66 nanofibers were successfully solution electrospun. The crystalline morphological features of HDPE solution induced by nanofibers were investigated by scanning electron microscopy (SEM). Nanohybrid shish-kebab (NHSK) can be formed in HDPE solution via isothermal crystallization, in which PA66 nanofibers serve as shish and HDPE lamellae act as kebabs surrounding the nanofibers periodically. Additionally, crystallization time has significant effect on the structure of HDPE kebab in NHSK, i.e., as crystallization time increases, the size of the kebab increases and the crystals decorated on PA66 nanofibers exhibit a three-dimensional growth (i.e., aggregate of crystallites) rather than a two-dimensional one (i.e., disc-like lamellae normal to the axis of nanofiber).

A Refined Single-Particle Reconstruction Procedure to Process Two-Dimensional Crystal Images from Transmission Electron Microscopy

2015 ◽  
Vol 21 (4) ◽  
pp. 876-885 ◽  
Author(s):  
Qie Kuang ◽  
Pasi Purhonen ◽  
Thirupathi Pattipaka ◽  
Yohannes H. Ayele ◽  
Hans Hebert ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Membrane Proteins ◽  
Single Particle ◽  
Three Dimensional ◽  
Reconstruction Procedure ◽  
Single Particle Reconstruction ◽  
Secondary Transporter ◽  
Unit Cells ◽  
2D Crystals ◽  
Particle Reconstruction

AbstractSingle-particle reconstruction (SPR) and electron crystallography (EC), two major applications in electron microscopy, can be used to determine the structure of membrane proteins. The three-dimensional (3D) map is obtained from separated particles in conventional SPR, but from periodic unit cells in EC. Here, we report a refined SPR procedure for processing 2D crystal images. The method is applied to 2D crystals of melibiose permease, a secondary transporter inEscherichia coli. The current procedure is improved from our previously published one in several aspects. The “gold standard Fourier shell correlation” resolution of our final reconstruction reaches 13 Å, which is significantly better than the previously obtained 17 Å resolution. The choices of different refinement parameters for reconstruction are discussed. Our refined SPR procedure could be applied to determine the structure of other membrane proteins in small or locally distorted 2D crystals, which are not ideal for EC.

Three-Dimensional reconstruction of the synaptonemal complex from pachytene maize meiocytes using Electron Microscopy tomography

1993 ◽  
Vol 51 ◽  
pp. 182-183
Author(s):  
Jennifer C. Fung ◽  
Bethe A. Scalettar ◽  
David A. Agard ◽  
John W. Sedat
Keyword(s):  
Electron Microscopy ◽  
Synaptonemal Complex ◽  
Chromosome Segregation ◽  
Three Dimensional ◽  
Central Element ◽  
Amorphous Structure ◽  
Two Dimensional ◽  
Homologous Chromosomes ◽  
Exact Function ◽  
Dimensional Reconstruction

The synaptonemal complex (SC) is a structure involved in the synapsis of homologous chromosomes during the prophase I stage of meiosis. Although the exact function of the complex is unknown, it has been suggested that one possible role might be to promote recombination by ensuring close synapsis of the homologous chromosomes. In addition, it is thought that the SC may also be required to convert the resulting recombination events into functional chiasmata to provide for proper chromosome segregation at the end of the first stage of meiosis.The SC structure itself is highly conserved across a variety of species. The organization of the SC is tripartite consisting of lateral, central and transverse elements. Two-dimensional cytological observations have been made to characterize the general features of these SC components. The lateral elements are 300 - 500 Å wide proteinaceous structures which flank the synapsed regions of the chromosome bivalent. Between the two lateral elements is a central region containing the central element commonly characterized as a less dense amorphous structure.

scholarly journals Recent Advances in Electron Tomography: TEM and HAADF-STEM Tomography for Materials Science and Semiconductor Applications

2005 ◽  
Vol 11 (5) ◽  
pp. 378-400 ◽  
Author(s):  
Christian Kübel ◽  
Andreas Voigt ◽  
Remco Schoenmakers ◽  
Max Otten ◽  
David Su ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Structural Information ◽  
Electron Tomography ◽  
Semiconductor Devices ◽  
Three Dimensional ◽  
Crystalline Materials ◽  
Transmission Electron ◽  
Stem Tomography

Electron tomography is a well-established technique for three-dimensional structure determination of (almost) amorphous specimens in life sciences applications. With the recent advances in nanotechnology and the semiconductor industry, there is also an increasing need for high-resolution three-dimensional (3D) structural information in physical sciences. In this article, we evaluate the capabilities and limitations of transmission electron microscopy (TEM) and high-angle-annular-dark-field scanning transmission electron microscopy (HAADF-STEM) tomography for the 3D structural characterization of partially crystalline to highly crystalline materials. Our analysis of catalysts, a hydrogen storage material, and different semiconductor devices shows that features with a diameter as small as 1–2 nm can be resolved in three dimensions by electron tomography. For partially crystalline materials with small single crystalline domains, bright-field TEM tomography provides reliable 3D structural information. HAADF-STEM tomography is more versatile and can also be used for high-resolution 3D imaging of highly crystalline materials such as semiconductor devices.

scholarly journals Crystallization, preliminary X-ray crystallographic and cryo-electron microscopy analysis of a bifunctional enzyme fucokinase/L-fucose-1-P-guanylyltransferase fromBacteroides fragilis

2014 ◽  
Vol 70 (9) ◽  
pp. 1206-1210 ◽  
Author(s):  
Chongyun Cheng ◽  
Jianhua Gu ◽  
Jing Su ◽  
Wei Ding ◽  
Jie Yin ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Analytical Ultracentrifugation ◽  
Structural Information ◽  
Three Dimensional ◽  
Size Exclusion ◽  
Diffusion Method ◽  
Bifunctional Enzyme ◽  
X Rays ◽  
Cell Parameters ◽  
Cryo Electron Microscopy

Fucokinase/L-fucose-1-P-guanylyltransferase (FKP) is a bifunctional enzyme which converts L-fucose to Fuc-1-P and thence to GDP-L-fucose through a salvage pathway. The molecular weights of full-length FKP (F-FKP) and C-terminally truncated FKP (C-FKP, residues 300–949) are 105.7 and 71.7 kDa, respectively. In this study, both recombinant F-FKP and C-FKP were expressed and purified. Size-exclusion chromatography experiments and analytical ultracentrifugation results showed that both F-FKP and C-FKP are trimers. Native F-FKP protein was crystallized by the vapour-diffusion method and the crystals belonged to space groupP212121and diffracted synchrotron X-rays to 3.7 Å resolution. The crystal unit-cell parameters area= 91.36,b= 172.03,c= 358.86 Å, α = β = γ = 90.00°. The three-dimensional features of the F-FKP molecule were observed by cryo-EM (cryo-electron microscopy). The preliminary cryo-EM experiments showed the F-FKP molecules as two parallel disc-shaped objects stacking together. Combining all results together, it is assumed that there are six FKP molecules in one asymmetric unit, which corresponds to a calculated Matthews coefficient of 2.19 Å3 Da−1with 43.83% solvent content. These preliminary crystallographic and cryo-EM microscopy analyses provide basic structural information on FKP.

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