scholarly journals Characterization by electron microscopy of isolated particles and two-dimensional crystals of the CP47-D1-D2-cytochrome b-559 complex of photosystem II

Biochemistry ◽  
1990 ◽  
Vol 29 (13) ◽  
pp. 3220-3225 ◽  
Author(s):  
Jan P. Dekker ◽  
Scott D. Betts ◽  
Charles F. Yocum ◽  
Egbert J. Boekema
Keyword(s):  
Electron Microscopy ◽  
Photosystem Ii ◽  
Cytochrome B ◽  
Two Dimensional

scholarly journals Structure of photosystem II in spinach thylakoid membranes: comparison of detergent-solubilized and native complexes by electron microscopy

1996 ◽  
Vol 315 (2) ◽  
pp. 543-547 ◽  
Author(s):  
William V. NICHOLSON ◽  
Fiona H. SHEPHERD ◽  
Mark F. ROSENBERG ◽  
Robert C. FORD ◽  
Andreas HOLZENBURG
Keyword(s):  
Electron Microscopy ◽  
Photosystem Ii ◽  
Rotational Symmetry ◽  
Thylakoid Membranes ◽  
Two Dimensional ◽  
Rectangular Shape ◽  
Ordered Arrays ◽  
Different Types ◽  
Spinach Thylakoid ◽  
Membrane Bound

1. Electron microscopy of solubilized photosystem II (PSII) complexes and PSII in spinach thylakoid membranes has been carried out and the results have been compared with data obtained from ordered two-dimensional arrays of PSII. Membrane-bound PSII is roughly rectangular (17.6 nm× 14.1 nm) with a central stain cavity surrounded by four major lumenal domains. A comparison between the averaged projections of single (non-ordered) particles at 3.8 nm resolution and the Fourier projection maps obtained from ordered arrays (at 2–3 nm resolution) reveals close similarity and excludes the possibility that PSII observed in two-dimensional ordered arrays represents an unusual subpopulation. 2. After detergent solubilization, PSII adopts various aggregation states which were analysed by electron microscopy in conjunction with single-particle averaging. Two different types of projection of roughly rectangular shape and of dimensions 30 nm×17 nm manifesting themselves as tetrameric sandwich structures have been revealed. This conclusion is supported by the presence of at least two axes of 2-fold rotational symmetry running perpendicular to each other and intersecting at the centre of the oligomer. Comparisons of the structures of detergent-solubilized and native PSII show that the oligomerization of PSII can be artificially induced by the process of membrane solubilization.

Two-dimensional Crystallization and Cryo-electron Microscopy of Photosystem II

1996 ◽  
Vol 257 (2) ◽  
pp. 225-232 ◽  
Author(s):  
Katsuyoshi Nakazato ◽  
Chikashi Toyoshima ◽  
Isao Enami ◽  
Yorinao Inoue
Keyword(s):  
Electron Microscopy ◽  
Photosystem Ii ◽  
Two Dimensional ◽  
Cryo Electron Microscopy

scholarly journals Two-dimensional crystals of photosystem II: biochemical characterization, cryoelectron microscopy and localization of the D1 and cytochrome b559 polypeptides.

1996 ◽  
Vol 132 (5) ◽  
pp. 823-833 ◽  
Author(s):  
K M Marr ◽  
D N Mastronarde ◽  
M K Lyon
Keyword(s):  
Electron Microscopy ◽  
Image Analysis ◽  
Photosystem Ii ◽  
Reaction Center ◽  
Biochemical Characterization ◽  
Higher Plants ◽  
Unit Cell ◽  
Two Dimensional ◽  
Cytochrome B559 ◽  
Ps Ii

Photosystem II (PS II) is a photosynthetic reaction center found in higher plants which has the unique ability to evolve oxygen from water. Several groups have formed two-dimensional PS II crystals or have isolated PS II complexes and studied them by electron microscopy and image analysis. The majority of these specimens have not been well characterized biochemically and have yielded relatively low resolution two-dimensional projection maps with a variety of unit cell sizes. We report the characterization of the polypeptide and lipid content of tubular crystals of PS II. The crystals contain the reaction center core polypeptides D1, D2, cytochrome b559, as well as the chlorophyll-binding polypeptides (CP) CP47, CP43, CP29, CP26, CP24, and CP22. The lipid composition was similar to the lipids found in the stacked portion of thylakoids. We also report a 2.0-nm resolution projection map determined by electron microscopy and image analysis of frozen, hydrated PS II crystals. This projection map includes information on the portion of the complex buried in the lipid bilayer. The unit cell is a dimer with unit vectors of 17.0 and 11.4 nm separated by an angle of 106.6 degrees. In addition, Fab fragments against D1 and cytochrome b559 were used to localize those two polypeptides, and thus the reaction center, within the PS II complex. The results indicate that D1 and cytochrome b559 are found within one of the heaviest densities of the monomeric unit.

Reconstruction of Two-Dimensional Projections of GP 32*I

1981 ◽  
Vol 39 ◽  
pp. 38-39
Author(s):  
H.A. Cohen ◽  
W. Chiu ◽  
J. Hosoda
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Uranyl Acetate ◽  
Distilled Water ◽  
Acetate Solution ◽  
Two Dimensional ◽  
Parent Molecule ◽  
T4 Bacteriophage ◽  
Electron Imaging ◽  
Better Than

GP 32 (molecular weight 35000) is a T4 bacteriophage protein that destabilizes the DNA helix. The fragment GP32*I (77% of the total weight), which destabilizes helices better than does the parent molecule, crystallizes as platelets thin enough for electron diffraction and electron imaging. In this paper we discuss the structure of this protein as revealed in images reconstructed from stained and unstained crystals.Crystals were prepared as previously described. Crystals for electron microscopy were pelleted from the buffer suspension, washed in distilled water, and resuspended in 1% glucose. Two lambda droplets were placed on grids over freshly evaporated carbon, allowed to sit for five minutes, and then were drained. Stained crystals were prepared the same way, except that prior to draining the droplet, two lambda of aqueous 1% uranyl acetate solution were applied for 20 seconds. Micrographs were produced using less than 2 e/Å2 for unstained crystals or less than 8 e/Å2 for stained crystals.

Parabolas from Reconstructed Surfaces Observed in Convergent-Beam RHEED Patterns

1990 ◽  
Vol 48 (2) ◽  
pp. 398-399
Author(s):  
M. Gajdardziska-Josifovska
Keyword(s):  
Electron Microscopy ◽  
High Energy ◽  
Two Dimensional ◽  
High Energy Electron ◽  
Reflection And Transmission ◽  
Experimental Diffraction Pattern ◽  
Surface Resonance ◽  
Reconstructed Surfaces ◽  
Reflection Electron Microscopy ◽  
Convergent Beam

Parabolas have been observed in the reflection high-energy electron diffraction (RHEED) patterns from surfaces of single crystals since the early thirties. In the last decade there has been a revival of attempts to elucidate the origin of these surface parabolas. The renewed interest stems from the need to understand the connection between the parabolas and the surface resonance (channeling) condition, the latter being routinely used to obtain higher intensity in reflection electron microscopy (REM) images of surfaces. Several rather diverging descriptions have been proposed to explain the parabolas in the reflection and transmission Kikuchi patterns. Recently we have developed an unifying general treatment in which the parabolas are shown to be K-lines of two-dimensional lattices. Here we want to review the main features of this description and present an experimental diffraction pattern from a 30° MgO (111) surface which displays parabolas that can be attributed to the surface reconstruction.

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 Two Dimensional Broadband Electronic Spectroscopy of Photosystem II Core Complexes

2013 ◽  
Vol 104 (2) ◽  
pp. 653a
Author(s):  
Henry D. Wilson ◽  
Franklin D. Fuller ◽  
Charles F. Yocum ◽  
Jennifer P. Ogilvie
Keyword(s):  
Photosystem Ii ◽  
Electronic Spectroscopy ◽  
Two Dimensional
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