Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Crystallization and Preliminary X-ray Diffraction Studies of New Crystal Forms of Escherichia coli PII Complexed with Various Ligands (1996)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 52 (1996), S. 738-742 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: New crystals of the signal-transducing protein PII have been obtained in the presence of a number of different effector ligands. Various crystal forms are observed depending on the nature of the ligand(s). Co-crystallization with 2-ketoglutarate, glutamate and pyrophosphate produces hexagonal crystals similar to the wild type, ATP yields cubic crystals and ATP in conjunction with 2-ketoglutarate or glutamate yields orthorhombic crystal forms. All of the above crystals have been characterized by X-ray diffraction analysis. The hexagonal crystals belong to space group P63, cubic crystals to either I23 or I213 and orthorhombic crystals to I222. A molecular-replacement solution for the PII/ATP/2-ketoglutarate crystals has been obtained giving us an initial model for a trimer in the orthorhombic crystal form.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444996003241
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    X-ray structure of the signal transduction protein from Escherichia coli at 1.9 Å (1996)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 52 (1996), S. 93-104 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The structure of the bacterial signal transduction protein PII has been refined to an R factor of 13.2% using 3σ data between 10 and 1.9 Å. The crystals exhibited twinning by merohedry and X-ray intensities were corrected using the method of Fisher & Sweet [Fisher & Sweet (1980). Acta Cryst. A36, 755–760] prior to refinement. Our earlier 2.7 Å structure [Cheah, Carr, Suffolk, Vasudevan, Dixon & Ollis (1994). Structure, 2, 981–990] served as a starting model. PII is a trimeric molecule, each subunit has a mass of 12.4 kDa and contains 112 amino-acid residues. The refined model includes all 1065 protein atoms per subunit plus 312 water molecules. The high-resolution refinement confirms the correctness of our 2.7 Å model, although it leads to a redefinition of the extent of various secondary-structural elements. The monomeric structure of PII exhibits an interlocking double βαβ fold. This is a stable fold found in a number of proteins with diverse functions. The association of the protein into a trimer leads to a new structure which we describe in detail. The effects of crystal packing forces are discussed and potential interaction sites with other proteins and effector molecules are identified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444995007293
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Synchrotron Radiation Laue Diffraction for the Time-Resolved Study of a Transformation in Crystals of P4N4Cl8 (1995)
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 2 (1995), S. 300-308 
    Details
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Experiments are described to show some of the potential of the synchrotron radiation Laue method for the study of structural change within single crystals. In the metastable tetragonal crystals of P4N4Cl8 the eight-membered P4N4 ring is in a boat conformation, with symmetry {\bar 4}. On heating to ca 340 K the crystals transform, slowly to a second tetragonal form in which the ring conformation is a chair, its symmetry {\bar 1}. Both structures are known [Hazekamp, Migchelsen & Vos (1962). Acta Cryst. 15, 539–543; Wagner & Vos (1968). Acta Cryst. B24, 707–713]. In the transformation the molecular packing, unit-cell dimensions and crystal quality remain almost unchanged. To study this transformation, series of Laue diffraction patterns were recorded at 2–3 min intervals over a period of 30–40 min, while the temperature was raised to 373 K. For two series, reflection intensities were measured and they allowed determination and refinement of the fraction of boat and chair molecules present in a mixed boat/chair model of the structure. No significant change in the crystal occurs below ca 340 K; at or above 340 K, 40–50% of the molecules are converted from boat to chair conformations within 5 min, but the remainder of the conversion is much slower, even when the temperature is raised towards 370 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0909049595012799
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    The determination of crystal size and disorder from X-ray diffraction photographs of polymer fibres. 1. The accuracy of determination of Fourier coefficients of the intensity profile of a reflection (1989)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 22 (1989), S. 363-371 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Methods which determine the number and disorder of lattice planes in a crystal from the Fourier cosine coefficients of the intensity profile of an X-ray reflection use only the low harmonics and require that the coefficients be normalized so that the zero harmonic is unity. Experimentally, the profiles can only be recorded over a smaller range of scattering angle than required by the theory, and it is necessary to subtract background, which is likely to be estimated with considerable error, before determining the coefficients. It is shown that with polymer fibres this causes serious errors in the normalization, and in the values of those low harmonics used in the size and disorder determination, and prevents reliable values being obtained. Methods which avoid normalization and use only high harmonics are needed. It is shown that disorder may be obtained in such a way, but not size, for which low-order normalized coefficients are essential. A method of extrapolation is described and tested which enables the accurate high harmonics to be used to improve the estimates of the low ones. Whilst this will yield more reliable values of crystal size than are obtainable from existing methods, the accuracy depends entirely on the validity of the extrapolation, which cannot be tested in many cases of interest.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889889004085
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    The determination of unit-cell parameters from Laue diffraction patterns using their gnomonic projections (1992)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 25 (1992), S. 294-308 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A method is described whereby the unit cell of a crystal and its orientation can be determined from a single Laue diffraction pattern (in transmission). The axial ratios and interaxial angles can be determined precisely, but the absolute scaling of the cell depends upon the accuracy with which the minimum wavelength for the experiment is known. Several examples are given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889891012803
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Ice-free cryo-cooling of protein crystals (1996)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 29 (1996), S. 469-470 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Modifications are described that eliminate ice build-up during data collection from cryo-cooled protein crystals using an RAXIS IIC imaging-plate system and its associated cool nitrogen gas stream apparatus (both supplied by Molecular Structure Corporation, The Woodlands, Texas, USA).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889895016347
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Estimation of dmin, λmin and λmax from the gnomonic projections of Laue patterns (1992)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 25 (1992), S. 285-293 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The parameters dmin and λmin, needed for the processing of synchrotron X-ray Laue patterns, may be estimated by simple formulae from the sizes of the clear gaps surrounding prominent zone lines in gnomonic projections. The estimation of λmax is similarly considered. Examples are given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889891012797
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    The determination of unit-cell parameters from a Laue diffraction pattern (1993)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 26 (1993), S. 384-387 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Single-crystal Laue diffraction patterns have not hitherto been used for the precise determination of unit-cell dimensions, although axial ratios and interaxial angles have frequently been derived. Here, we use an attenuator such as 0.1 mm palladium foil in the white synchrotron-radiation beam incident on the crystal; the absorption edge (e.g. palladium at 0.509 Å) then sharply defines the minimum wavelength present. With gnomonic projections in the manner described by Carr, Cruickshank & Harding [J. Appl. Cryst. (1992), 25, 294–308], the unit-cell dimensions on an absolute scale can be derived. Three tests show that these dimensions are correct to circa 0.5%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889892012391
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Small-angle-X-ray scattering by crystalline polymer fibres 1. Experimental method and investigation of the linear paracrystalline model (1987)
    Springer
    Colloid & polymer science 265 (1987), S. 383-393 
    Details
    ISSN: 1435-1536
    Keywords: Small-angleX-ray ; linearparacrystal ; poly(butylene terephthalate) ; orientedpolymerfibre
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Hosemann's formula for X-ray scattering by a linear paracrystal is investigated using the distribution of intensity parallel to the fibre axis of oriented poly(butylene terephthalate). The formula was put into a form suitable for numerical analysis, and a stepping refinement procedure used to adjust the paracrystalline parameters so that the discrepancy between the calculated and measured intensity was minimised. The measured intensity had been corrected for the spread of scattering transverse to the fibre axis before making this comparison. The pin-hole collimation system was designed so that resolution was limited only by the linear position-sensitive detector, and was good enough not to distort the recorded scattering distribution. Although parasitic scatter could not be measured to the same accuracy, it was so small that negligible error was introduced when it was subtracted. “Top-hat”, Gaussian and Reinhold distribution functions for the lengths of the two phases all fitted well in the region of the main peak although detailed analysis suggested significant disagreement on the low-angle side. Only the asymmetric Reinhold function fitted around the third-order peak and beyond. The range of parameter values giving a good fit for this distribution were determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01412216
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...