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  • 1
    Electronic Resource
    Electronic Resource
    CCD Video Observation of Microgravity Crystallization of Lysozyme and Correlation with Accelerometer Data (1997)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 53 (1997), S. 747-755 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Lysozyme has been crystallized using the ESA Advanced Protein Crystallization Facility onboard the NASA Space Shuttle Orbiter during the IML-2 mission. CCD video monitoring was used to follow the crystallization process and evaluate the growth rate. During the mission some tetragonal crystals were observed moving over distances of up to 200 μm. This was correlated with microgravity disturbances caused by firings of vernier jets on the Orbiter. Growth-rate measurement of a stationary crystal (which had nucleated on the growth reactor wall) showed spurts and lulls correlated with an onboard activity: astronaut exercise. The stepped growth rates may be responsible for the residual mosaic block structure seen in crystal mosaicity and topography measurements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444997007968
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Crystallization of chicken egg-white lysozyme from ammonium sulfate (1997)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 53 (1997), S. 795-797 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Chicken egg-white lysozyme was crystallized from ammonium sulfate over the pH range 4.0–7.8, with protein concentrations from 100 to 150 mg ml−1. Crystals were obtained by vapor-diffusion or batch-crystallization methods. The protein crystallized in two morphologies with an apparent morphology dependence on temperature and protein concentration. In general, tetragonal crystals could be grown by lowering the protein concentration or temperature. Increasing the temperature or protein concentration resulted in the growth of orthorhombic crystals. Representative crystals of each morphology were selected for X-ray analysis. The tetragonal crystals belonged to the P43212 space group with crystals grown at pH 4.4 having unit-cell dimensions of a = b = 78.71, c = 38.6 Å and diffracting to beyond 2.0 Å. The orthorhombic crystals, grown at pH 4.8, were of space group P21212 and had unit-cell dimensions of a = 30.51, b = 56.51 and c = 73.62 Å.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444997006896
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Synchrotron X-ray reciprocal-space mapping, topography and diffraction resolution studies of macromolecular crystal quality (2000)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 56 (2000), S. 868-880 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: A comprehensive study of microgravity and ground-grown chicken egg-white lysozyme crystals is presented using synchrotron X-ray reciprocal-space mapping, topography techniques and diffraction resolution. Microgravity crystals displayed reduced intrinsic mosaicities on average, but no differences in terms of strain over their ground-grown counterparts. Topographic analysis revealed that in the microgravity case the majority of the crystal was contributing to the peak of the reflection at the appropriate Bragg angle. In the ground-control case only a small volume of the crystal contributed to the intensity at the diffraction peak. The techniques prove to be highly complementary, with the reciprocal-space mapping providing a quantitative measure of the crystal mosaicity and strain (or variation in lattice spacing) and the topography providing a qualitative overall assessment of the crystal in terms of its X-ray diffraction properties. Structural data collection was also carried out at the synchrotron.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444900005837
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  • 4
    Electronic Resource
    Electronic Resource
    Improvements in lysozyme protein crystal perfection through microgravity growth (1995)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 51 (1995), S. 1099-1102 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Microgravity offers an environment for protein crystallization where there is an absence of convection and sedimentation. We have investigated the effect of microgravity conditions on the perfection of protein crystals. The quality of crystals for X-ray diffraction studies is characterized by a number of factors, namely size, mosaicity and the resolution limit. By using tetragonal lysozyme crystals as a test case we show, with crystal growth in two separate Space Shuttle missions, that the mosaicity is improved by a factor of three to four over earth-grown ground control values. These microgravity-grown protein crystals are then essentially perfect diffraction gratings. As a result the peak to background of individual X-ray diffraction reflections is enhanced by a similar factor to the reduction in the mosaicity. This then offers a particularly important opportunity for improving the measurement of weak reflections such as occur at high diffraction resolution. These microgravity results set a benchmark for all future microgravity and earth-based protein crystallography procedures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444995012170
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  • 5
    Electronic Resource
    Electronic Resource
    Lysozyme Crystal Growth Kinetics Monitored Using a Mach–Zehnder Interferometer (1996)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 52 (1996), S. 529-533 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: A Mach-Zehnder interferometer has been developed for the monitoring of the kinetics of the diffusion process in protein crystal growth. This device can be used in conjunction with the ESA Advanced Protein Crystallization Facility (APCF), which allows experiments under microgravity conditions (e.g. on board the NASA Space Shuttle). Experimental trials on the ground have been carried out with the interferometer using the engineering model of the APCF and a protein dialysis reactor. Chicken egg-white lysozyme crystal growth, as a test, has thereby been monitored directly. The changes of concentration in the solution over time have been determined via the refractive index measurements made and subsequently correlated with visual monitoring of crystal growth in a repeat experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S090744499600042X
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  • 6
    Electronic Resource
    Electronic Resource
    Partial Improvement of Crystal Quality for Microgravity-Grown Apocrustacyanin C1 (1997)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 53 (1997), S. 231-239 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The protein apocrustacyanin C1 has been crystallized by vapour diffusion in both microgravity (the NASA space shuttle USML-2 mission) and on the ground. Rocking width measurements were made on the crystals at the ESRF Swiss-Norwegian beamline using a high-resolution ψ-circle diffractometer from the University of Karlsruhe. Crystal perfection was then evaluated, from comparison of the reflection rocking curves from a total of five crystals (three grown in microgravity and two earth controls), and by plotting mosaicity versus reflection signal/noise. Comparison was then made with previous measurements of almost `perfect' lysozyme crystals grown aboard IML-2 and Spacehab-I and reported by Snell et al. [Snell, Weisgerber, Helliwell, Weckert, Hölzer & Schroer (1995). Acta Cryst. D51, 1099–1102]. Overall, the best diffraction-quality apocrustacyanin C1 crystal was microgravity grown, but one earth-grown crystal was as good as one of the other microgravity-grown crystals. The remaining two crystals (one from microgravity and one from earth) were poorer than the other three and of fairly equal quality. Crystal movement during growth in microgravity, resulting from the use of vapour-diffusion geometry, may be the cause of not realising the `theoretical' limit of perfect protein crystal quality.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444996013996
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