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Topic: Electron crystallography

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	Crystallography - Wikipedia, the free encyclopedia
		Crystallography (from the Greek words crystallon = cold drop / frozen drop, with its meaning extending to all solids with some degree of transparency, and graphein = write) is the experimental science of determining the arrangement of atoms in solids.
		Crystallography covers the enumeration of the symmetry patterns which can be formed by atoms in a crystal and for this reason has a relation to group theory and geometry.
		X-ray crystallography is the primary method for determining the molecular conformations of biological macromolecules, particularly protein and nucleic acids such as DNA and RNA.
	en.wikipedia.org /wiki/Crystallography (1501 words)

	LMS: About LMS
		Electron crystallography, such as the diffraction mode in transmission electron microscopy (TEM) and reflection high energy electron diffraction (RHEED), has been developed over the last 30 years as a structure determination method with high sensitivity and atomic-scale spatial resolution.
		The electrons are generated through the photoelectric effect by back-illumination with a femtosecond laser pulse on a silver photo-cathode.
		With the electron gun focusing system, both the reflection and transmission diffractions can be obtained, and the patterns are recorded by an intensified CCD camera assembly capable of single electron detection.
	www.its.caltech.edu /~lms/research/ultrafast.html (738 words)

	Applications of CCD camera in electron crystallography
		Electron crystallography has become a realistic technique for solving the atomic resolution structure of biological macromolecules that are arranged in two-dimensional periodic arrays (Henderson et al.
		The highest possible number of electron diffraction patterns, that could be acquired with the slow-scan CCD camera from a single crotoxin complex crystal under the constraints of radiation damage, was assessed by recording successive patterns from the same crystal.
		Its applicability to protein electron crystallography at 400 kV has resulted from a number of engineering changes, that were made to the slow-scan CCD camera, such as minimization of the spurious X-ray signals picked up by the camera.
	ncmi.bcm.tmc.edu /~brink/papers/ccd-edps/ccd.html (7994 words)

	Chapter 5 -- Electron Crystallography
		Electron crystallography [Henderson et al., 1990] can then be used to determine the protein structure at atomic resolution.
		Electron crystallography provided the first insight into the structure of the PS I reaction center [Ford et al., 1990].
		Sharp spots extend to a resolution of 7.5 Å, and the circular zones of the contrast transfer function are clearly depicted.
	www.mih.unibas.ch /Booklet/Booklet96/Chapter5/Chapter5.html (1798 words)

	[No title] (Site not responding. Last check: 2007-11-03)
		As solid state electronic devices continue to shrink, a larger percentage of the atoms in the devices reside at a surface or interface, and therefore surfaces and interfaces are playing a role of increasing importance in determining the behavior of microelectronic structures.
		Surface crystallography is the study of surface crystal structure and is important to the understanding of interface phenomena.
		Quantum surface crystallography takes this one step further in an attempt to experimentally measure the structure of the electrons themselves, which is of greater importance than atomic positions in determining material properties.
	www.numis.northwestern.edu /Research/Current/current.shtml (1448 words)

	Crystallography Summary
		Crystallography is the study of the formation processes that produce crystals, and of the structural and identifying details of crystals.
		Crystallography is the study of materials in which the atoms stack in a three-dimensionally ordered geometric arrangement.
		During the next fifty years, x-ray crystallography was used to examine the molecular structure of thousands of crystalline substances and was instrumental in the syntheses of penicillin and, later, insulin.
	www.bookrags.com /Crystallography (8757 words)

	FRISC > Faculty Profiles > Zbyszek Otwinowski, Ph.D.
		Electron crystallography of macromolecular periodic arrays on phospholipid monolayers.
		Electron crystallography at atomic resolution: ab initio structure analysis of copper perchlorophthalocyanine.
		Electron imaging and diffraction study of individual crystals of bone, mineralized tendon and synthetic carbonate apatite.
	invention.swmed.edu /frisc/faculty/otwinows/profile.shtml (3847 words)

	European Crystallographic Association - SIG4: Electron Crystallography
		The aim of the SIG is to raise the awareness, acceptance and general standard of Electron crystallography, i.e.
		Development of electron crystallography is usually carried out in electron microscopy labs, with relatively small research groups as one of several materials research activities.
		Electron microscopy is often necessary anyway, in order to characterize the material, ascertain Bravias lattice and unit cell dimension - or because small crystal size, internal surfaces, defects or precipitates are inherent aspects of the material.
	www.ecanews.org /sig4.htm (1075 words)

	Electron crystallography - Wikipedia, the free encyclopedia
		Electron crystallography is a method to determine the arrangement of atoms in solids using an electron microscope.
		One of the main difficulties in X-ray crystallography is determining phases in the diffraction pattern.
		The first electron crystallographic protein structure to achieve atomic resolution was bacteriorhodopsin, determined by Richard Henderson and coworkers at the Medical Research Council Laboratory of Molecular Biology in 1990.
	en.wikipedia.org /wiki/Electron_crystallography (418 words)

	Electron crystallography (Site not responding. Last check: 2007-11-03)
		Electron crystallography originally developed by Henderson and Unwin for structure determination of 2-dimensional (2D) crystals of membrane proteins has now revealed the atomic resolution of bacteriorhodopsin (1), the light harvesting complex (2) and the tubulin (3).
		A projection map (Figure 1) of the full-length protein at 9Å resolution was obtained by electron cryo-microscopy and image analysis of frozen-hydrated two-dimensional crystals.
		Electron microscopy of two-dimensional crystals on a Nickel-chelating lipid.
	biop.ox.ac.uk /www/lj2000/venien/venien_01.html (1043 words)

	Electron Crystallography School - Moscow 2003
		Structure determination by electron diffraction and electron microscopy – electron crystallography – is becoming increasingly important for the structural characterization materials especially those that only exist as submicron sized powders (including pigments, pharmaceuticals, catalysts and many minerals) or which are only available in extremely small fractions such as thin films and nanocryastalline powders.
		Institute of Crystallography of the Russian Academy of Sciences was a fatherland of the method of electron diffraction structure analysis and many structures of crystals and amorphous substances have been solved in it where the School will take place.
		All lecturers are established scientists in the field of electron crystallography.
	ns.crys.ras.ru /msec2003/main.htm (492 words)

	Ingeborg Schmidt-Krey, Assistant Professor: Biology
		Electron crystallography is the main tool employed to study these proteins in my laboratory.
		The approach of 2D crystallization and electron crystallography is particularly suitable for highly fragile membrane proteins such as many eukaryotic ones.
		Although electron crystallographic methods are well developed, little is known about the factors important in 2D crystallization, and screening protocols as for 3D crystallization do not exist.
	www.biology.gatech.edu /faculty/ingeborg-schmidtkrey (459 words)

	STRUCTURAL ELECTRON CRYSTALLOGRAPHY
		In electron crystallography, an electron microscope is used to obtain two- and three-dimensional diffraction patterns from very small crystals.
		It is possible to see individual atoms and their positions with modern electron microscopes having a resolution below 2 Å, and this is sufficient for solving an unknown structure of organic molecules and inorganic compounds.
		Some electron diffraction data and structure factors of materials are also given as tables in this second part of the book.
	www.cap.ca /BRMS/Reviews/Structural-Dorset-Uguz.html (508 words)

	Picturing proteins
		When this electron microscopy information is combined with the x-ray data on various substructures within the complex-a technique dubbed "hybrid crystallography"-Nogales and her colleagues expect to find further clues as to how the transcriptional machinery comes together.
		With x-ray crystallography to determine the 3-D structures of protein components and electron microscopy to show how these components fit into complexes, there is still a need to zoom in for the finer details of electronic properties in order to see how a protein machine performs its chemical functions.
		In exafs, the electron is ejected from the atom as a photoelectron and the resulting spectrum provides extremely accurate measurements of electron bond lengths.
	www.eurekalert.org /features/doe/2000-12/drnl-pp061902.php (2904 words)

	Asturias Laboratory - Abstract - Yeast RNAPII Electron Crystallography
		Electron cyrstallography of yeast RNA polymerase II preserved in vitreous ice
		An electron density projection map of the enzyme was calculated from the data, which extended to a resolution of about 12 Å, but was unexpectedly weak at resolutions higher than about 20 Å.
		Electron microscopic studies of other large multiprotein complexes are likely to require similar approaches to those described here.
	www.scripps.edu /cb/asturias/index.php?page=70 (173 words)

	Image Analysis and 3D Reconstruction
		Hoppe, W. (1979) Three-dimensional electron microscopy of individual structures: Crystallography of 'Crystals' consisting of a single unit cell.
		Smith, P. Aebi, R. Josephs and M. Kessel (1976) Studies of the structure of the T4 bacteriophage tail sheath I. The recovery of three-dimensional structural information from the extended sheath (Appendix: The determination of the helical screw angle of a helical particle from its diffraction pattern).
		Three-dimensional reconstruction of nonperiodic macromolecular assemblies from electron micrographs.
	bilbo.bio.purdue.edu /~baker/ref/IP/whole.html (2404 words)

	Electron Crystallography
		Electron crystallography involves the use of the electron microscope to obtain 2- and 3-dimensional diffraction patterns from nanocrystals.
		The method has been used to break the 1Å resolution barrier by obtaining an electron density map and image of perchlorocoronene from electron microscopy and diffraction data The ME formalism has been used for other structures of interest to materials scientists in the fields of non-linear optical materials and alloys.
		The process of refinement in crystallography is used to validate your proposed model.
	www.chem.gla.ac.uk /staff/chris/electron.html (564 words)

	Mystery Of Vital Cell Protein Solved After 30 Years
		The use of electron-based rather than the x-ray-based crystallography techniques customarily employed in protein studies was crucial to the model's 3.7 angstrom resolution.
		The final 3-D model is a computerized reconstruction derived from a data set that included 93 electron diffraction patterns and 159 images culled by the researchers from the more than 4,000 images which were recorded over a six-year period.
		The diffraction patterns and images were generated on an electron microscope equipped with a special "cold stage" that reduced damage to the crystals from the electron beam and yielded less "noise" than a conventional electron microscope.
	www.eurekalert.org /pub_releases/1998-01/LBNL-MOVC-080198.php (898 words)

	W0197: Electron Crystallography: A Routine Method (Site not responding. Last check: 2007-11-03)
		Maximum entropy techniques have been employed to extrapolate successfully into reciprocal space and predict some of the "missing cone" of data caused by the limited tilt of the microscopes stage.
		Due to the nature of electron crystallography your intensities often contain a small amount of dynamical scattering, making structure solution by standard single crystal techniques nearly impossible.
		Therefore the use of the maximum entropy program MICE, is a useful tool for electron crystallographers solving 3 dimensional electron diffraction data sets.
	www.hwi.buffalo.edu /ACA/ACA01/abstracts/text/W0197.html (227 words)

	HHMI Bulletin February 2006: Optical Aspirations
		Grigorieff and others also use electron microscopy to visualize two-dimensional crystals of membrane proteins in a lipid bilayer, much like that in the cell.
		In December, Walz reported using this technique, called electron crystallography, to determine the three-dimensional structure of a cellular water-pore protein called aquaporin; the resolution was high enough to spot discrete lipid molecules clinging to the side of the protein.
		Electron microscope images of single protein complexes (as opposed to crystals) have lower resolution, but they can distinguish parts of proteins, such as helices and loops.
	www.hhmi.org /bulletin/feb2006/features/optical4.html (503 words)

	Electron Microscopy: Creating A Model
		Electron crystallography is similar to x-ray crystallography in that it exploits the repeating pattern found within a crystal to generate a structure.
		Just as with x-ray crystallography, difraction patterns are generated and are used to define an electron density map.
		However, it differs in that the crystal used is a two-dimensional sheet as opposed to three three-dimensional crystals of x-ray crystallography.
	cryoem.berkeley.edu /~nieder/em_for_dummies/model.html (453 words)

	Quantitative Comparison of Zero-Loss and Conventional Electron Diffraction from Two-Dimensional and Thin ...
		Electron crystallography has been widely applied to determine the structures of biological macromolecules.
		Deviations of the positions of reflections from the ideal ones were obtained from diffraction patterns from F41 crystals, and deviation vectors are drawn on corresponding reflections to represent the lattice image distortion.
		Vonck, J. Structure of the bacteriorhodopsin mutant F219L N intermediate revealed by electron crystallography.
	www.biophysj.org /cgi/content/full/82/5/2784 (6046 words)

	Structural Biology
		Among the methods being used to examine macromolecular structure are x-ray crystallography, electron microscopy, mass spectrometry, biochemical and genetic analysis, and computer-assisted structural modeling.
		For membrane transport, we use electron crystallography to study helical assemblies of Ca-ATPase and its relatives in the family of P-type ATPases.
		For intercellular adhesion, we use electron tomography to map the molecular architecture of desmosomes and adherens junctions in situ.
	saturn.med.nyu.edu /research/sb (1016 words)

	Amazon.com: Electron Crystallography (NATO Science Series E:): Books: D. Dorset,Sven Hovmöller,Xiaodong Zou (Site not responding. Last check: 2007-11-03)
		The re-emergent field of quantitative electron crystallography is described by some of its most eminent practitioners.
		They describe the theoretical framework for electron scattering, specimen preparation, experimental techniques for optimum data collection, the methodology of structure analysis and refinement, and a range of applications to inorganic materials (including minerals), linear polymers, small organic molecules (including those used in nonlinear optical devices), incommensurately modulated structures (including superconductors), alloys, and integral membrane proteins.
		The connection between electron crystallography and X-ray crystallography is clearly defined, especially in the utilisation of the latest methods for direct determination of crystallographic phases, as well as the unique role of image analysis of high-resolution electron micrographs for phase determination.
	www.amazon.com /Electron-Crystallography-NATO-Science-E/dp/0792348761 (838 words)

	NRAMM
		Electron crystallography has brought a rigorous crystallographic approach to the analysis of electron images and electron diffraction patterns from two-dimensional crystals.
		Structural analysis by electron microscopy of biological macromolecules or macromolecular assemblies embedded in rapidly frozen, vitreous ice has made great advances during the last few years.
		Although it has been possible, using crystalline or helical specimens, to reach a resolution adequate to build atomic models (4 Ångstroms), there is every hope this will soon also be possible with single particles.
	nramm.scripps.edu /seminars/2004/dlecture (352 words)

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