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  • 1
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 56 (2000), S. 973-985 
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Laue data reduction has now reached a level of sophistication that allows nearly automated processing to be performed. The software described enables complete reduction of the data with essentially no user intervention, making Laue processing almost as straightforward as monochromatic data processing. Interactive work is limited to the indexing of only one Laue pattern. More importantly, it is shown that the data quality is substantially enhanced when soft-limited predictions are used. Further improvement obtained by taking advantage of the structure-factor amplitudes from a known closely related structure is described. To determine the most suitable type of insertion device to be used for time-resolved Laue crystallography, the technique described was applied to Laue data sets collected from photoactive yellow protein under identical conditions but with three different insertion devices: a wiggler, a broad-bandpass undulator and a single-line undulator. Although the optimal choice may ultimately be dictated by sample parameters (such as mosaic spread) and by the type of experiment (repeatable or non-repeatable reactions), the results here show that the use of single-line undulators will generally yield by far the best compromise between data quality, acquisition time and radiation damage.
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  • 2
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Developments in electronic area detectors such as CCDs and image plates have transformed the capability of the synchrotron Laue protein crystallography technique compared with film. The rapid readout of CCDs makes practical the use of rather fine angular interval settings of the crystal between each Laue exposure and a large overall angle coverage. The use of the ESRF CCD (image intensifier type) presented here in the Laue data collection on ESRF ID09 (the `Laue beamline') from a single crystal of the 34 kDa wild-type hydroxymethylbilane synthase (HMBS), space group P21212 a = 88.06, b = 75.73, c = 50.35 Å, yielded 47 Laue exposures in 2.5° angle intervals from a single crystal. The data processed by the Daresbury Laue software is highly complete (∞–2dmin = 77.5%; 2dmin–dmin= 91.7%) to 2.3 Å with high redundancy (11.2). Comparison with calculated structure factors and careful analysis of the Laue geometry shows that between ∞ and 5dmin better completeness still should be possible, which can ideally be realized from CCD detector dynamic range hardware improvements and/or software algorithms to integrate saturated spot profiles. Prospects for Laue diffraction data collection using yet faster detectors such as the `pixel detector' to study irreversible catalytic structural processes in a crystal, the most challenging of all time-resolved experiments, are bright.
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  • 3
    Electronic Resource
    Electronic Resource
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 3 (1996), S. 65-74 
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Laue diffraction patterns with an exposure time of ca 60 ps have been acquired at the European Synchrotron Radiation Facility (ESRF) on protein crystals by using the single-bunch mode of the storage ring. A 10 ns laser pulse initiating photodissociation was synchronized with the X-ray pulse. The potential for a quantitative detection of conformational changes in proteins on the nanosecond timescale with this technique is demonstrated using the example of carbonmonoxymyoglobin, from simulations and real data. The instrumental aspects of the experiment (highly intense X-ray beam, fast shutter system, Laue camera, detector, laser apparatus and synchronization technique) are emphasized.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 30 (1997), S. 153-163 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The potential of very rapid Laue data collection for time-resolved studies down to the 150 ps timescale has been demonstrated in the case of cutinase, a 22 kDa lipolytic enzyme for which a considerable amount of structural information is available. This paper reports the derivation of the structure of native cutinase at 1.5 Å from a Laue data set recorded at the White Beam Station of the European Synchrotron Radiation Facility (ESRF), with a total exposure time of 8.5 ns. The structure of the heteromorphous mutant R196E was chosen as a starting model for refinement, in order to check whether these fast Laue data were of sufficient quality to allow an accurate structure determination from a strongly biased starting model. This analysis is relevant because similar situations are encountered in fast time-resolved experiments where rapid structural modifications of a protein are analysed from fast Laue data sets, recorded in some excited states of the protein, and from a structural model representative of the rest state. 19 Laue images were recorded with 150 ps X-ray pulses emitted by a single electron bucket from the ESRF storage ring. With two insertion devices used in series, tile available photon flux was sufficient to refine a satisfactory model of native cutinase (Rcryst = 19.3%; Rfree = 24.2%). Discrepancies between this model and an accurate atomic model of cutinase (obtained from monochromatic data collected to 1.0 Å, resolution, Rcryst = 9.7%) were minor and mainly due to the nonoptimal completeness of the data (71.7% to 1.5 Å) and to the different extent in resolution. The wild-type Arg196 could be readily positioned in the electron density and significant main- and side-chain displacements due to packing constraints were successfully retrieved with the Laue data. The electron-density maps were of sufficient quality to solve unambiguously these structural modifications. This feasibility study shows that very rapid Laue diffraction is a powerful tool to study protein dynamics in real time, provided that suitable macromolecular crystals as well as efficient reaction-triggering techniques are available.
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  • 5
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Wavelength normalization is an essential part of processing of Laue X-ray diffraction data and is critically important for deriving accurate structure-factor amplitudes. The results of wavelength normalization for Laue data obtained in nanosecond time-resolved experiments at the ID09 beamline at the European Synchrotron Radiation Facility, Grenoble, France, are presented. Several wiggler and undulator insertion devices with complex spectra were used. The results show that even in the most challenging cases, such as wiggler/undulator tandems or single-line undulators, accurate wavelength normalization does not require unusually redundant Laue data and can be accomplished using typical Laue data sets. Single-line undulator spectra derived from Laue data compare well with the measured incident X-ray spectra. Successful wavelength normalization of the undulator data was also confirmed by the observed signal in nanosecond time-resolved experiments. Single-line undulators, which are attractive for time-resolved experiments due to their high peak intensity and low polychromatic background, are compared with wigglers, based on data obtained on the same crystal.
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  • 6
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 33 (1977), S. 637-641 
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 56 (2000), S. 33-34 
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: In the title complex, tetraphenylphosphonium μ4-nitrato-κ4O-cyclo-tetrakis(μ-acetato-O:O′)tetra-μ-oxo-tetrakis[oxovana-dium(V)], the anion lies about a twofold axis and consists of the cyclic [V4O8] unit coordinated by four acetato ligands with interatomic V...V distances of 3.269 (1) and 3.273 (1) Å. The double-bonded O atom [N=O 1.102 (6) and N—O 1.268 (4) Å] of the nitrato ligand links the four V atoms with V—O bond distances of 2.613 (2) and 2.813 (2) Å. The negative charge of the complex is balanced by tetraphenylphosphonium cations occupying the Na positions in the NaCl-type ionic packing of the structure.
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 54 (1998), S. 0-0 
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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