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See detailCrystal structure of trisodium iron diphosphate, Na2.88Fe(PO4)(2), a synthetic phosphate with hannayite-type heteropolyhedral chains
Hatert, Frédéric ULg

in Zeitschrift für Kristallographie. New Crystal Structures (2007), 222(1), 6-8

FeNa2.88O8P2, triclinic, P (1) over bar (no. 2), a 5.3141(6) b = 8.5853(9) angstrom, c = 8.7859(8) angstrom, alpha = 114.429(9)degrees, beta = 92.327(9)degrees, gamma = 106.08(1)degrees, V = 345.1 ... [more ▼]

FeNa2.88O8P2, triclinic, P (1) over bar (no. 2), a 5.3141(6) b = 8.5853(9) angstrom, c = 8.7859(8) angstrom, alpha = 114.429(9)degrees, beta = 92.327(9)degrees, gamma = 106.08(1)degrees, V = 345.1 angstrom(3),Z = 2, Rgt(F) = 0.028, wR(ref)(F-2) = 0.087, T = 293 K. [less ▲]

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See detailCrystal structures of complexes of bacterial DD-peptidases with peptidoglycan-mimetic ligands: the substrate specificity puzzle.
Sauvage, Eric ULg; Powell, Ailsa J; Heilemann, Jason et al

in Journal of Molecular Biology (2008), 381(2), 383-93

The X-ray crystal structures of covalent complexes of the Actinomadura R39 dd-peptidase and Escherichia coli penicillin-binding protein (PBP) 5 with beta-lactams bearing peptidoglycan-mimetic side chains ... [more ▼]

The X-ray crystal structures of covalent complexes of the Actinomadura R39 dd-peptidase and Escherichia coli penicillin-binding protein (PBP) 5 with beta-lactams bearing peptidoglycan-mimetic side chains have been determined. The structure of the hydrolysis product of an analogous peptide bound noncovalently to the former enzyme has also been obtained. The R39 DD-peptidase structures reveal the presence of a specific binding site for the D-alpha-aminopimelyl side chain, characteristic of the stem peptide of Actinomadura R39. This binding site features a hydrophobic cleft for the pimelyl methylene groups and strong hydrogen bonding to the polar terminus. Both of these active site elements are provided by amino acid side chains from two separate domains of the protein. In contrast, no clear electron density corresponding to the terminus of the peptidoglycan-mimetic side chains is present when these beta-lactams are covalently bound to PBP5. There is, therefore, no indication of a specific side-chain binding site in this enzyme. These results are in agreement with those from kinetics studies published earlier and support the general prediction made at the time of a direct correlation between kinetics and structural evidence. The essential high-molecular-mass PBPs have demonstrated, to date, no specific reactivity with peptidoglycan-mimetic peptide substrates and beta-lactam inhibitors and, thus, probably do not possess a specific substrate-binding site of the type demonstrated here with the R39 DD-peptidase. This striking deficiency may represent a sophisticated defense mechanism against low-molecular-mass substrate-analogue inhibitors/antibiotics; its discovery should focus new inhibitor design. [less ▲]

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See detailCrystal structures of oxidized and reduced forms of human mitochondrial thioredoxin 2
Smeets, Aude; Evrard, Christine ULg; Landtmeters, Marie et al

in Protein Science : A Publication of the Protein Society (2005), 14

Mammalian thioredoxin 2 is a mitochondrial isoform of highly evolutionary conserved thioredoxins. Thioredoxins are small ubiquitous protein–disulfide oxidoreductases implicated in a large variety of ... [more ▼]

Mammalian thioredoxin 2 is a mitochondrial isoform of highly evolutionary conserved thioredoxins. Thioredoxins are small ubiquitous protein–disulfide oxidoreductases implicated in a large variety of biological functions. In mammals, thioredoxin 2 is encoded by a nuclear gene and is targeted to mitochondria by a N-terminal mitochondrial presequence. Recently, mitochondrial thioredoxin 2 was shown to interact with components of the mitochondrial respiratory chain and to play a role in the control of mitochondrial membrane potential, regulating mitochondrial apoptosis signaling pathway. Here we report the first crystal structures of a mammalian mitochondrial thioredoxin 2. Crystal forms of reduced and oxidized human thioredoxin 2 are described at 2.0 and 1.8A ˚ resolution. Though the folding is rather similar to that of human cytosolic/nuclear thioredoxin 1, important differences are observed during the transition between the oxidized and the reduced states of human thioredoxin 2, compared with human thioredoxin 1. In spite of the absence of the Cys residue implicated in dimer formation in human thioredoxin 1, dimerization still occurs in the crystal structure of human thioredoxin 2, mainly mediated by hydrophobic contacts, and the dimers are associated to form two-dimensional polymers. Interestingly, the structure of human thioredoxin 2 reveals possible interaction domains with human peroxiredoxin 5, a substrate protein of human thioredoxin 2 in mitochondria. [less ▲]

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See detailCrystal structures of the Bacillus licheniformis BS3 class A beta-lactamase and of the acyl-enzyme adduct formed with cefoxitin
Fonzé, Evelyne; Vanhove, Mac; Dive, Georges ULg et al

in Biochemistry (2002), 41(6), 1877-1885

The Bacillus licheniformis BS3 beta-lactamase catalyzes the hydrolysis of the beta-lactam ring of penicillins, cephalosporins, and related compounds. The production of beta-lactamases is the most common ... [more ▼]

The Bacillus licheniformis BS3 beta-lactamase catalyzes the hydrolysis of the beta-lactam ring of penicillins, cephalosporins, and related compounds. The production of beta-lactamases is the most common and thoroughly studied cause of antibiotic resistance. Although they escape the hydrolytic activity of the prototypical Staphylococcus aureus beta-lactamase, many cephems are good substrates for a large number of beta-lactamases. However, the introduction of a 7alpha-methoxy substituent, as in cefoxitin, extends their antibacterial spectrum to many cephalosporin-resistant Gram-negative bacteria. The 7alphamethoxy group selectively reduces the hydrolytic action of many beta-lactamases without having a significant effect on the affinity for the target enzymes, the membrane penicillin-binding proteins. We report here the crystallographic structures of the BS3 enzyme and its acyl-enzyme adduct with cefoxitin at 1.7 Angstrom resolution. The comparison of the two structures reveals a covalent acyl-enzyme adduct with perturbed active site geometry, involving a different conformation of the Omega-loop that bears the essential catalytic Glu166 residue. This deformation is induced by the cefoxitin side chain whose position is constrained by the presence of the alpha-methoxy group. The hydrolytic water molecule is also removed from the active site by the 7beta-carbonyl of the acyl intermediate. In light of the interactions and steric hindrances in the active site of the structure of the BS3-cefoxitin acyl-enzyme adduct, the crucial role of the conserved Asn132 residue is confirmed and a better understanding of the kinetic results emerges. [less ▲]

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See detailCrystal structures of the psychrophilic a-amylase from Alteromonas haloplanctis in its native form and complexed with an inhibitor
Aghajari, N.; Feller, Georges ULg; Gerday, Charles ULg et al

in Protein Science : A Publication of the Protein Society (1998), 7(6), 564-572

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See detailCrystal-field effects on the thermal conductivity of localized spin metallic compounds
Rassili, Ahmed ULg; Durczewski, K.; Ausloos, Marcel ULg

in Physical Review. B : Condensed Matter (1998), 58(9), 5665-5671

The influence of the crystal-electric-field (CEF) splitting on the thermal conductivity is calculated on the basis of a two-level system model applicable to intermetallic magnetic compounds. The localized ... [more ▼]

The influence of the crystal-electric-field (CEF) splitting on the thermal conductivity is calculated on the basis of a two-level system model applicable to intermetallic magnetic compounds. The localized spin scattering contribution kappa(s), in a manner similar to the total electronic thermal conductivity kappa(e), shows a larger increase at low and intermediate temperatures as compared to the case iii which-no crystal-electric-field splitting is taken into account. The influence of some theoretical parameters is also discussed. It is shown that the CEF effect enhances the effect of the magnetic scattering potential, and impurity contributions screen such an enhancement at temperatures below the Debye temperature. Other scattering contributions, e.g., electron-phonon and electron impurities, are also taken into account in our calculation. The theory is in quantitative agreement with data on RA1(2) systems taken as test cases, and leads to values of the level splitting in the 50 K range. [less ▲]

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See detailCrystallization and preliminary X-ray analysis of a bacterial psychrophilic enzyme, phosphoglycerate kinase
Mandelman, D.; Bentahir, M.; Feller, Georges ULg et al

in Acta Crystallographica Section D-Biological Crystallography (2001), 57(Pt 11), 1666-8

The glycolytic enzyme phosphoglycerate kinase (PGK) from the Antarctic microorganism Pseudomonas sp. TACII18 is a cold-adapted enzyme that displays a high specific activity at low temperatures and ... [more ▼]

The glycolytic enzyme phosphoglycerate kinase (PGK) from the Antarctic microorganism Pseudomonas sp. TACII18 is a cold-adapted enzyme that displays a high specific activity at low temperatures and decreased thermostability relative to its mesophilic counterpart. Herein, the preliminary crystallization and structure solution of psychrophilic PGK in its native form and cocrystallized with 3-phosphoglyceric acid (3-PGA) and the ATP analogue adenylyl imidophosphate (AMP-PNP) is reported. The complexed form of PGK crystallized in 2-3 d at 290 K, whereas the native form of the enzyme required 8-12 months. Morphologically, both crystal forms are similar and X-ray diffraction experiments indicate that the crystals are isomorphous. The crystals diffracted to a resolution of 2.0 A and belong to the space group P3(2). with unit-cell parameters a = b = 58.5, c = 85.4 A. [less ▲]

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See detailCrystallization and preliminary X-ray analysis of a new L-aminopeptidase-D-amidase/D-esterase activated by a Gly-Ser peptide bond hydrolysis.
Bompard-Gilles, C; Villeret, V; Fanuel, L et al

in Acta Crystallographica Section D-Biological Crystallography (1999), 55(Pt 3), 699-701

Ochrobactrum anthropi possesses an L-aminopeptidase (DmpA) also able to act as a D-amidase/D-esterase. DmpA (40 kDa) is activated by auto-catalyzed protein splicing liberating an alpha-amino group ... [more ▼]

Ochrobactrum anthropi possesses an L-aminopeptidase (DmpA) also able to act as a D-amidase/D-esterase. DmpA (40 kDa) is activated by auto-catalyzed protein splicing liberating an alpha-amino group presumably used as a general base in the catalytic mechanism. Two crystal forms were obtained at 294 K in 13-16% PEG 2000 mono-methylether at pH 9.0, adding either 0.2 M magnesium chloride or 1 M lithium chloride. Crystals of the first form belong to the space group C2221 and diffract to 3.0 A resolution, whereas crystals of the second form belong to the space group P21212 and diffract to 2.3 A resolution. Initial screening for heavy-atom derivatives on form II crystals, has led to a well substituted Hg derivative. [less ▲]

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See detailCrystallization and preliminary X-ray analysis of a xylanase from the psychrophile Pseudoalteromonas haloplanktis
Van Petegem, F.; Collins, T.; Meuwis, Marie-Alice ULg et al

in Acta Crystallographica Section D-Biological Crystallography (2002), 58(Part 9), 1494-1496

The 46 kDa xylanase from the Antarctic microorganism Pseudoalteromonas haloplanktis is an enzyme that efficiently catalyzes reactions at low temperatures. Here, the crystallization of both the native ... [more ▼]

The 46 kDa xylanase from the Antarctic microorganism Pseudoalteromonas haloplanktis is an enzyme that efficiently catalyzes reactions at low temperatures. Here, the crystallization of both the native protein and the SeMet-substituted enzyme and data collection from both crystals using synchrotron radiation are described. The native data showed that the crystals diffract to 1.3 Angstrom resolution and belong to space group P2(1)2(1)2(1), with unit-cell parameters a = 50.87, b = 90.51, c = 97.23 Angstrom. SAD data collected at the peak of the selenium absorption edge proved to be sufficient to determine the heavy-atom configuration and to obtain electron density of good quality. [less ▲]

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See detailCrystallization and preliminary X-ray analysis of bacteriophage lambda lysozyme in which all tryptophans have been replaced by aza-tryptophans
Evrard, Christine ULg; Declercq, Jean-Paul; Fastrez, Jacques

in Acta Crystallographica Section D-Biological Crystallography (1997), D53

After many unsuccessful attempts to crystallize the bacteriophage lambda lysozyme, a mutant where all the tryptophan residues have been replaced by aza-tryptophans has been crystallized by the vapor ... [more ▼]

After many unsuccessful attempts to crystallize the bacteriophage lambda lysozyme, a mutant where all the tryptophan residues have been replaced by aza-tryptophans has been crystallized by the vapor-diffusion method. The crystals are orthorhombic and belong to space group P212121 with cell dimensions a = 73.01, b = 78.80, c = 82.31 Å. Diffraction data were collected using synchrotron radiation sources. Crystals diffract to a resolution of 2.3 Å. Data from two different platinum derivatives were also recorded to 2.8 and 2.5 Å, respectively. [less ▲]

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See detailCrystallization and preliminary X-ray data for parvalbumin IIIf of Opsanus tau.
Hamoir, G.; Dideberg, O.; Charlier, Paulette ULg

in Journal of Molecular Biology (1981), 153(2), 487-9

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See detailCrystallization and preliminary X-ray data for the exocellular beta-lactamase of Bacillus licheniformis 749/C.
Dideberg, O.; Libert, M.; Frère, Jean-Marie ULg et al

in Journal of Molecular Biology (1985), 181(1), 145-6

The exocellular beta-lactamase from Bacillus licheniformis 749/C has been crystallized from polyethylene glycol solution at pH 5.5. An X-ray examination of the monoclinic crystals shows the space group is ... [more ▼]

The exocellular beta-lactamase from Bacillus licheniformis 749/C has been crystallized from polyethylene glycol solution at pH 5.5. An X-ray examination of the monoclinic crystals shows the space group is P21, with unit cell dimensions a = 66.77 A, b = 93.77 A, c = 43.57 A and beta = 104.5 degrees. The asymmetric unit consists of two molecules of 28,500 Mr each. The crystals are suitable for structure analysis to at least 2 A resolution. [less ▲]

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See detailCrystallization and preliminary X-ray diffraction studies of a-amylase from the antarctic psychrophile Alteromonas haloplanctis A23
Aghajari, N.; Feller, Georges ULg; Gerday, Charles ULg et al

in Protein Science : A Publication of the Protein Society (1996), 5(10), 2128-2129

A cold-active alpha-amylase was purified from culture supernatants of the antarctic psychrophile Alteromonas haloplanctis A23 grown at 4 degrees C. In order to contribute to the understanding of the ... [more ▼]

A cold-active alpha-amylase was purified from culture supernatants of the antarctic psychrophile Alteromonas haloplanctis A23 grown at 4 degrees C. In order to contribute to the understanding of the molecular basis of cold adaptations, crystallographic studies of this cold-adapted enzyme have been initiated because a three-dimensional structure of a mesophilic counterpart, pig pancreatic alpha-amylase, already exists. alpha-Amylase from A. haloplanctis, which shares 53% sequence identity with pig pancreatic alpha-amylase, has been crystallized and data to 1.85 A have been collected. The space group is found to be C222(1) with a = 71.40 A, b = 138.88 A, and c = 115.66 A. Until now, a three-dimensional structure of a psychrophilic enzyme is lacking. [less ▲]

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See detailCrystallization and X-ray diffraction study of the Streptomyces K15 penicillin-binding DD-transpeptidase.
Englebert, S.; Charlier, Paulette ULg; Fonze, E. et al

in Journal of Molecular Biology (1994), 241(2), 295-7

The 262 amino acid residue long DD-transpeptidase/penicillin-binding protein of Streptomyces K15 has been crystallized at room temperature by using the hanging drop vapour diffusion technique. The ... [more ▼]

The 262 amino acid residue long DD-transpeptidase/penicillin-binding protein of Streptomyces K15 has been crystallized at room temperature by using the hanging drop vapour diffusion technique. The crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit cell parameters a = 46.4 A, b = 54.1 A and c = 108.3 A. They contain one protein molecule per asymmetric unit and diffract to about 1.9 A. X-ray data have been collected to 2.0 A from a native crystal. The previously published amino acid sequence of the protein has been corrected at positions 71, 72, 113, 114 and 156. [less ▲]

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See detailCrystallization of a genetically engineered water-soluble primary penicillin target enzyme. The high molecular mass PBP2x of Streptococcus pneumoniae.
Charlier, Paulette ULg; Buisson, G.; Dideberg, O. et al

in Journal of Molecular Biology (1993), 232(3), 1007-9

A genetically engineered water-soluble derivative of PBP2x of Streptococcus pneumoniae has been produced, purified and crystallized in a form suitable for X-ray diffraction analysis. The best crystals ... [more ▼]

A genetically engineered water-soluble derivative of PBP2x of Streptococcus pneumoniae has been produced, purified and crystallized in a form suitable for X-ray diffraction analysis. The best crystals have been grown at 15 degrees C, from solutions containing 8% polyethylene glycol 10,000 at pH values ranging from 3.9 to 6.0. These crystals diffract to a resolution of 3.5 A and have a space group P6(1)22 (or enantiomorph) with unit cell dimensions of a = b = 162.2 A, c = 171.8 A, alpha = beta = 90 degrees, gamma = 120 degrees. The molecular mass and cell dimensions suggest that there is one molecule of enzyme per asymmetric unit. The breakdown of a chromogenic cephalosporin derivative diffused into a crystal reveals clearly that the enzyme is active in the crystalline state. [less ▲]

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See detailCrystallization of ornithine acetyltransferase from yeast by counter-diffusion and preliminary X-ray study
Maes, D.; Crabeel, M.; Van de Weerdt, Cécile ULg et al

in Acta Crystallographica Section F-Structural Biology and Crystallization Communications (2006), 62(Part 12), 1294-1297

A study is presented on the crystallization of ornithine acetyltransferase from yeast, which catalyzes the fifth step in microbial arginine synthesis. The use of the counter-diffusion technique removes ... [more ▼]

A study is presented on the crystallization of ornithine acetyltransferase from yeast, which catalyzes the fifth step in microbial arginine synthesis. The use of the counter-diffusion technique removes the disorder present in one dimension in crystals grown by either the batch or hanging-drop techniques. This makes the difference between useless crystals and crystals that allow successful determination of the structure of the protein. The crystals belong to space group P4, with unit-cell parameters a = b = 66.98, c = 427.09 angstrom, and a data set was collected to 2.76 angstrom. [less ▲]

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See detailCrystallization of vitreous high-T-c superconducting oxide through laser zone melting method.
Ausloos, Marcel ULg; Bougrine, Hassan ULg; Cloots, Rudi ULg et al

in Institute of Physics Conference Series (1995), 148

We synthesized Bi2Sr2CaCu2O8-y ceramics through the vitreous route. After insertion in epoxy resin, we exposed the materials to a CO2 laser beam. Various intensities and sweeping conditions were examined ... [more ▼]

We synthesized Bi2Sr2CaCu2O8-y ceramics through the vitreous route. After insertion in epoxy resin, we exposed the materials to a CO2 laser beam. Various intensities and sweeping conditions were examined. We observed the samples in high resolution polarized light microscopy and with electron scanning microscopy. Crystallization zones could be detected. A systematic analysis gave the correlation between the behavior of the material and its synthesis conditions. Electrical properties were measured through micro-electrode deposited on the surface at various locations. No superconductivity was found. The optimization of such a process and potential applications will be discussed. [less ▲]

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See detailCrystallization sequence and magma chamber processes in the ferrobasaltic Sept Iles layered intrusion, Canada
Namur, Olivier ULg; Charlier, Bernard ULg; Toplis, Michael et al

in Journal of Petrology (2010), 51

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See detailCrystallization, X-ray characterization and selenomethionine phasing of Mlc1p bound to IQ motifs from myosin V
Terrak, Mohammed ULg; Otterbein, L. R.; Wu, G. et al

in Acta Crystallographica Section D-Biological Crystallography (2002), 58(Pt 10 Pt 2), 1882-5

Mlc1p is a calmodulin-like protein from the budding yeast Saccharomyces cerevisiae, where it has been identified as a subunit of a class V myosin, Myo2p, and a binding partner of an IQGAP-like protein ... [more ▼]

Mlc1p is a calmodulin-like protein from the budding yeast Saccharomyces cerevisiae, where it has been identified as a subunit of a class V myosin, Myo2p, and a binding partner of an IQGAP-like protein, Iqg1p. Through its interactions with these two proteins, Mlc1p plays a role in polarized growth and cytokinesis. Mlc1p has been crystallized in complexes with four different IQ target motifs from the neck region of Myo2p: IQ2, IQ3, IQ4 and IQ2-IQ3 (referred to as IQ2,3). Electron-density maps for two of the complexes (Mlc1p-IQ4 and Mlc1p-IQ2,3) were obtained from multiple anomalous dispersion (MAD) experiments based on selenomethionine derivatives. The other two structures (Mlc1p-IQ2 and Mlc1p-IQ3) were determined by molecular replacement using the partially refined structure of Mlc1p-IQ2,3 as a search model. [less ▲]

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