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Synchrotron Diffraction Data (synchrotron + diffraction_data)
Selected AbstractsPurification, crystallization and preliminary X-ray analysis of the ,-lactamase Oih-1 from Oceanobacillus iheyensisACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 6 2009Marta Toth Bacterial resistance to the ,-lactam family of antibiotics is primarily the result of the deactivation of the drugs by ,-lactamase enzymes. The gene encoding the proficient ,-lactamase Oih-1 from the alkaliphilic and halotolerant Gram-positive bacterium Oceanobacillus iheyensis has been cloned and the mature wild-type protein (comprising 274 amino-acid residues) has been expressed in Escherichia coli and subsequently purified to homogeneity. Oih-1 crystallized in two crystal forms both belonging to the trigonal space group P3121 but with distinctly different unit-cell parameters. Synchrotron diffraction data were collected to high resolution (1.65,1.75,Å) from both crystal forms on beamlines BL7-1 and BL11-1 at SSRL (Stanford, California, USA). [source] Crystallization and preliminary X-ray studies of the N-domain of the Wilson disease associated proteinACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 6 2009Lili Liu Wilson disease associated protein (ATP7B) is essential for copper transport in human cells. Mutations that affect ATP7B function result in Wilson's disease, a chronic copper toxicosis. Disease-causing mutations within the N-domain of ATP7B (WND) are known to disrupt ATP binding, but a high-resolution X-ray structure of the ATP-binding site has not been reported. The N-domain was modified to delete the disordered loop comprising residues His1115,Asp1138 (WND,1115,1138). Unlike the wild-type N-domain, WND,1115,1138 formed good-quality crystals. Synchrotron diffraction data have been collected from WND,1115,1138 at the Canadian Light Source. A native WND,1115,1138 crystal diffracted to 1.7,Å resolution and belonged to space group P42212, with unit-cell parameters a = 39.2, b = 39.2, c = 168.9,Å. MAD data were collected to 2.7,Å resolution from a SeMet-derivative crystal with unit-cell parameters a = 38.4, b = 38.4, c = 166.7,Å. The WND,1115,1138 structure is likely to be solved by phasing from multiwavelength anomalous diffraction (MAD) experiments. [source] Structure and conformational analysis of a bidentate pro-ligand, C21H34N2S2, from powder synchrotron diffraction data and solid-state DFTB calculationsACTA CRYSTALLOGRAPHICA SECTION B, Issue 5 2009Edward E. Ávila The molecular and crystalline structure of ethyl 1,,2,,3,,4,,4a,,5,,6,,7,-octahydrodispiro[cyclohexane-1,2,-quinazoline-4,,1,,-cyclohexane]-8,-carbodithioate (I) was solved and refined from powder synchrotron X-ray diffraction data. The initial model for the structural solution in direct space using the simulated annealing algorithm implemented in DASH [David et al. (2006). J. Appl. Cryst.39, 910,915] was obtained performing a conformational study on the fused six-membered rings of the octahydroquinazoline system and the two spiran cyclohexane rings of (I). The best model was chosen using experimental evidence from 1H and 13C NMR [Contreras et al. (2001). J. Heterocycl. Chem.38, 1223,1225] in combination with semi-empirical AM1 calculations. In the refined structure the two spiran rings have the chair conformation, while both of the fused rings in the octahydroquinazoline system have half-chair conformations compared with in-vacuum density-functional theory (DFT) B3LYP/6-311G*, DFTB (density-functional tight-binding) theoretical calculations in the solid state and other related structures from X-ray diffraction data. Compound (I) presents weak intramolecular hydrogen bonds of the type N,H...S and C,H...S, which produce delocalization of the electron density in the generated rings described by graph symbols S(6) and S(5). Packing of the molecules is dominated by van der Waals interactions. [source] Structures of mono-unsaturated triacylglycerols.ACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2008The ,-2 crystal structures of a series of saturated and trans -mono-unsaturated triacylglycerols (TAGs) have been solved from high-resolution powder synchrotron diffraction data. The series comprises symmetric as well as asymmetric even-numbered TAGs and the trans -mono-unsaturated ones all have a single elaidoyl chain. The structures have been solved with the direct-space parallel-tempering program FOX and refined with the Rietveld program GSAS. The ,-2 structures all crystallized in the space group with the same molecular conformation. Within the resolution of the data no significant difference in packing or conformation is observed between trans -mono-unsaturated TAGs and saturated (stearoyl or palmitoyl) chain-containing analogues, in spite of the lower melting points of the former. An analysis of the position of the stepped methyl end-plane in the various subgroups of TAGs confirms most but not all suppositions found in the literature. [source] Purification, crystallization and preliminary X-ray analysis of Enterococcus casseliflavus aminoglycoside-2,,-phosphotransferase-IVaACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 1 2010Marta Toth The deactivation of aminoglycoside antibiotics by chemical modification is one of the major sources of bacterial resistance to this family of therapeutic compounds, which includes the clinically relevant drugs streptomycin, kanamycin and gentamicin. The aminoglycoside phosphotransferases (APHs) form one such family of enzymes responsible for this resistance. The gene encoding one of these enzymes, aminoglycoside-2,,-phosphotransferase-IVa [APH(2,,)-IVa] from Enterococcus casseliflavus, has been cloned and the protein (comprising 306 amino-acid residues) has been expressed in Escherichia coli and purified. The enzyme was crystallized in three substrate-free forms. Two of the crystal forms belonged to the orthorhombic space group P212121 with similar unit-cell parameters, although one of the crystal forms had a unit-cell volume that was approximately 13% smaller than the other and a very low solvent content of around 38%. The third crystal form belonged to the monoclinic space group P21 and preliminary X-ray diffraction analysis was consistent with the presence of two molecules in the asymmetric unit. The orthorhombic crystal forms of apo APH(2,,)-IVa both diffracted to 2.2,Å resolution and the monoclinic crystal form diffracted to 2.4,Å resolution; synchrotron diffraction data were collected from these crystals at SSRL (Stanford, California, USA). Structure determination by molecular replacement using the structure of the related enzyme APH(2,,)-IIa is proceeding. [source] Crystallization and preliminary crystallographic characterization of glutamine synthetase from Medicago truncatulaACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 12 2009Ana Rita Seabra The condensation of ammonium and glutamate into glutamine catalyzed by glutamine synthetase (GS) is a fundamental step in nitrogen metabolism in all kingdoms of life. In plants, this is preceded by the reduction of inorganic nitrogen to an ammonium ion and therefore effectively articulates nitrogen fixation and metabolism. Although the three-dimensional structure of the dodecameric bacterial GS was determined quite some time ago, the quaternary architecture of the plant enzyme has long been assumed to be octameric, mostly on the basis of low-resolution electron-microscopy studies. Recently, the crystallographic structure of a monocotyledonous plant GS was reported that revealed a homodecameric organization. In order to unambiguously establish the quaternary architecture of GS from dicotyledonous plants, GS1a from the model legume Medicago truncatula was overexpressed, purified and crystallized. The collection of synchrotron diffraction data to 2.35,Å resolution allowed the determination of the three-dimensional structure of this enzyme by molecular replacement. [source] | ||||||||||