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Multiple-wavelength Anomalous Dispersion (multiple-wavelength + anomalous_dispersion)
Selected AbstractsMAD techniques applied to powder data: finding the structure given the substructureACTA CRYSTALLOGRAPHICA SECTION A, Issue 4 2009Angela Altomare The joint probability distribution function method is applied to multiple-wavelength anomalous dispersion (MAD) powder data. The distributions are calculated by assuming prior knowledge of the scattering intensities at two wavelengths and of the anomalous-scatterer substructure. The method leads to formulas estimating the full structure phases and their reliability. The procedure has been applied to two structures, one unknown and one known; the second was used as a control for the phasing procedure. In spite of the unavoidable peak overlapping in the diffraction pattern, the formulas proved to be very effective. Combined with a new algorithm for phase extension, they enabled the solution of both crystal structures. [source] Structure analysis of the conserved methyltransferase domain of human trimethylguanosine synthase TGS1ACTA CRYSTALLOGRAPHICA SECTION D, Issue 4 2009Thomas Monecke Methyltransferases play an important role in the post-transcriptional maturation of most ribonucleic acids. The modification of spliceosomal UsnRNAs includes N2-dimethylation of the m7G cap catalyzed by trimethylguanosine synthase 1 (TGS1). This 5,-cap hypermethylation occurs during the biogenesis of UsnRNPs as it initiates the m3G cap-dependent nuclear import of UsnRNPs. The conserved methyltransferase domain of human TGS1 has been purified, crystallized and the crystal structure of this domain with bound substrate m7GpppA was solved by means of multiple-wavelength anomalous dispersion. Crystal structure analysis revealed that m7GpppA binds via its adenosine moiety to the structurally conserved adenosylmethionine-binding pocket, while the m7 guanosine remains unbound. This unexpected binding only occurs in the absence of AdoMet and suggests an incomplete binding pocket for the m7G cap which is caused by the N-terminal truncation of the protein. These structural data are consistent with the finding that the crystallized fragment of human TGS1 is catalytically inactive, while a fragment that is 17 amino acids longer exhibits activity. [source] Crystallization of FLINC4, an intramolecular LMO4,ldb1 complexACTA CRYSTALLOGRAPHICA SECTION D, Issue 8 2003Janet E. Deane LMO4 is the most recently discovered member of a small family of nuclear transcriptional regulators that are important for both normal development and disease processes. LMO4 is comprised primarily of two tandemly repeated LIM domains and interacts with the ubiquitous nuclear adaptor protein ldb1. This interaction is mediated via the LIM domains of LMO4 and the LIM-interaction domain (LID) of ldb1. An intramolecular complex, termed FLINC4, consisting of the two LIM domains from LMO4 linked to the LID domain of ldb1 via a flexible linker has been engineered, purified and crystallized. The trigonal crystals, which belong to space group P312 with unit-cell parameters a = 61.3, c = 93.2,Å, diffract to 1.3,Å resolution and contain one molecule of FLINC4 per asymmetric unit. Native and multiple-wavelength anomalous dispersion (MAD) data collected at the Zn X-ray absorption edge have been recorded to 1.3 and 1.7,Å resolution, respectively. Anomalous Patterson maps calculated with data collected at the peak wavelength show strong peaks sufficient to determine the positions of four Zn atoms per asymmetric unit. [source] Structure of the conserved hypothetical protein MAL13P1.257 from Plasmodium falciparumACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 3 2006Margaret A. Holmes The structure of a conserved hypothetical protein, PlasmoDB sequence MAL13P1.257 from Plasmodium falciparum, Pfam sequence family PF05907, has been determined as part of the structural genomics effort of the Structural Genomics of Pathogenic Protozoa consortium. The structure was determined by multiple-wavelength anomalous dispersion at 2.17,Å resolution. The structure is almost entirely ,-sheet; it consists of 15 ,-strands and one short 310 -helix and represents a new protein fold. The packing of the two monomers in the asymmetric unit indicates that the biological unit may be a dimer. [source] | ||||||||||