Ultrafast structural studies on biological molecules by x-rays

1999 ◽  
Author(s):  
Janos Hajdu ◽  
Richard Neutze ◽  
Remco Wouts ◽  
David van der Spoel
Keyword(s):  
Biological Molecules ◽  
X Rays ◽  
Structural Studies

Structural studies of small amorphous volumes by electron diffraction

1990 ◽  
Vol 48 (4) ◽  
pp. 122-123
Author(s):  
Pierre Moine
Keyword(s):  
Electron Diffraction ◽  
Born Approximation ◽  
Structural Information ◽  
Fundamental Relation ◽  
X Rays ◽  
Structural Studies ◽  
Diffraction Experiment ◽  
Transmission Electron ◽  
Amorphous Structures ◽  
Diffraction Patterns

Qualitatively, amorphous structures can be easily revealed and differentiated from crystalline phases by their Transmission Electron Microscopy (TEM) images and their diffraction patterns (fig.1 and 2) but, for quantitative structural information, electron diffraction pattern intensity analyses are necessary. The parameters describing the structure of an amorphous specimen have been introduced in the context of scattering experiments which have been, so far, the most used techniques to obtain structural information in the form of statistical averages. When only small amorphous volumes (< 1/μm in size or thickness) are available, the much higher scattering of electrons (compared to neutrons or x rays) makes, despite its drawbacks, electron diffraction extremely valuable and often the only feasible technique.In a diffraction experiment, the intensity IN (Q) of a radiation, elastically scattered by N atoms of a sample, is measured and related to the atomic structure, using the fundamental relation (Born approximation) : IN(Q) = |FT[U(r)]|.

scholarly journals The uses of softer X-rays in structural studies

2005 ◽  
Vol 12 (4) ◽  
pp. 391-391
Author(s):  
R. J. Cernik ◽  
J. R. Helliwell ◽  
M Helliwell
Keyword(s):  
X Rays ◽  
Structural Studies

ChemInform Abstract: The Influence of X-Rays on the Structural Studies of Peroxide-Derived Myoglobin Intermediates

ChemInform ◽  
2009 ◽  
Vol 40 (2) ◽  
Author(s):  
Hans-Petter Hersleth ◽  
Ya-Wen Hsiao ◽  
Ulf Ryde ◽  
Carl Henrik Goerbitz ◽  
K. Kristoffer Andersson
Keyword(s):  
X Rays ◽  
Structural Studies

The potential and limitations of neutrons, electrons and X-rays for atomic resolution microscopy of unstained biological molecules

1995 ◽  
Vol 28 (2) ◽  
pp. 171-193 ◽  
Author(s):  
Richard Henderson
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Radiation Damage ◽  
Single Molecule ◽  
Biological Molecules ◽  
Atomic Resolution ◽  
Fast Neutrons ◽  
X Rays ◽  
Number Of Particles

SummaryRadiation damage is the main problem which prevents the determination of the structure of a single biological macromolecule at atomic resolution using any kind of microscopy. This is true whether neutrons, electrons or X-rays are used as the illumination. Forneutrons, the cross-section for nuclear capture and the associatedenergy deposition and radiation damage could be reduced by using samples that are fully deuterated and15N-labelled and by using fast neutrons, but single molecule biological microscopy is still not feasible. For naturally occurring biological material,electronsat present provide the most information for a given amount of radiation damage. Using phase contrast electron microscopy on biological molecules and macromolecular assemblies of ˜ 105molecular weight and above, there is in theory enough information present in the image to allow determination of the position and orientation of individual particles: the application of averaging methods can then be used to provide an atomic resolution structure. The images of approximately 10000 particles are required. Below 105molecular weight, some kind of crystal or other geometrically ordered aggregate is necessary to provide a sufficiently high combined molecular weight to allow for the alignment. In practice, the present quality of the best images still falls short of that attainable in theory and this means that a greater number of particles must be averaged and that the molecular weight limitation is somewhat larger than the predicted limit. ForX-rays, the amount of damage per useful elastic scattering event is several hundred times greater than for electrons at all wavelengths and energies and therefore the requirements on specimen size and number of particles are correspondingly larger. Because of the lack of sufficiently bright neutron sources in the foreseeable future, electron microscopy in practice provides the greatest potential for immediate progress.

scholarly journals Crystallography of lamin A facilitated by chimeric fusions

2020 ◽  
Author(s):  
Giel Stalmans ◽  
Anastasia V. Lilina ◽  
Sergei V. Strelkov
Keyword(s):  
Coiled Coil ◽  
Divide And Conquer ◽  
Lamin A ◽  
Molecular Replacement ◽  
X Rays ◽  
Structural Studies ◽  
Disulphide Bridge ◽  
Dimer Interface ◽  
Chimeric Construct ◽  
Further Development

AbstractAll proteins of the intermediate filament (IF) family contain the signature central α-helical domain which forms a coiled-coil dimer. Because of its length, past structural studies relied on a ‘divide-and-conquer’ strategy whereby fragments of this domain were recombinantly produced, crystallized and analysed using X-rays. Here we describe a further development of this approach towards structural studies of nuclear IF protein lamin. To this end, we have fused lamin A fragments to short N- and C-terminal capping motifs which provide for the correct formation of parallel, in-register coiled-coil dimers. As the result, a chimeric construct containing lamin A residues 17-70 C-terminally capped by the Eb1 domain was solved to 1.83 Å resolution. Another chimera containing lamin A residues 327-403 N-terminally capped by the Gp7 domain was solved to 2.9 Å. In the latter case the capping motif was additionally modified to include a disulphide bridge at the dimer interface. We discuss multiple benefits of fusing coiled-coil dimers with such capping motifs, including a convenient crystallographic phasing by either molecular replacement or sulphur single-wavelength anomalous dispersion (S-SAD) measurements.

scholarly journals What is an `ideally imperfect' crystal? Is kinematical theory appropriate?

2016 ◽  
Vol 72 (1) ◽  
pp. 50-54 ◽  
Author(s):  
Paul F. Fewster
Keyword(s):  
Dynamical Theory ◽  
Experimental Results ◽  
Biological Molecules ◽  
X Rays ◽  
Interatomic Distances ◽  
Atoms And Molecules ◽  
Imperfect Crystal ◽  
Diffraction Patterns ◽  
Inorganic Molecules ◽  
Kinematical Theory

Most materials are crystalline because atoms and molecules tend to form ordered arrangements, and since the interatomic distances are comparable with the wavelength of X-rays, their interaction creates diffraction patterns. The intensity in these patterns changes with crystal quality. Perfect crystals,e.g. semiconductors, fit well to dynamical theory, whereas crystals that reveal the stereochemistry of complex biological molecules, the structure of organic and inorganic molecules and powders are required to be fragmented (termed `ideally imperfect') to justify the use of the simpler kinematical theory. New experimental results of perfect and imperfect crystals are interpreted with a fundamental description of diffraction, which does not need fragmented crystals but just ubiquitous defects. The distribution of the intensity is modified and can influence the interpretation of the patterns.

Brightest X-rays ever give researchers brand-new view of biological molecules

JAMA ◽  
1994 ◽  
Vol 272 (11) ◽  
pp. 837-839
Author(s):  
A. A. Skolnick
Keyword(s):  
Biological Molecules ◽  
X Rays ◽  
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