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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 ULiege

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 ULiege; 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 ULiege; 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 ULiege 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 ULiege; Gerday, Charles ULiege 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 ULiege; Durczewski, K.; Ausloos, Marcel ULiege

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 detailCrystallisation-driven self-assembly of poly(2-isopropyl-2- oxazoline)-block-poly(2-methyl-2-oxazoline) above the LCST
Legros, Camille ULiege; De Pauw-Gillet, Marie-Claire ULiege; Tam, Kam Chiu et al

in Soft Matter (2015)

The solution behaviour in water of a polyoxazoline-type block copolymer, namely poly(2- isopropyl-2-oxazoline)-block-poly(2-methyl-2-oxazoline), denoted as P(iPrOx-b-MeOx), above the lower critical ... [more ▼]

The solution behaviour in water of a polyoxazoline-type block copolymer, namely poly(2- isopropyl-2-oxazoline)-block-poly(2-methyl-2-oxazoline), denoted as P(iPrOx-b-MeOx), above the lower critical solution temperature (LCST) of the PiPrOx block was exploited to induce a temporary or permanent self-assembly. Spherical micelles were first obtained and could be disassembled in a reversible manner when kept for a short period of time (i.e. t < 1h30) above the LCST, and cooled down to room temperature. In contrast, annealing the copolymer solution for more than 1h30 at 65 °C induced the crystallisation of the PiPrOx block, as evidenced by wide angle X-ray scattering (WAXS) experiments. This crystallisationdriven self-assembly phenomenon resulted in different morphologies, including spherical and distorted crystallised micelles and micron-size fibers, their relative proportion varying with annealing time. Formation of micron-size range fiber-like structures might be explained by a re-organization of parent crystallised micelles. The crystal structure, as determined by WAXS, appeared to be identical to that of the PiPrOx homopolymer. [less ▲]

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See detailCrystallization and Gelation Behavior of Low- and High Melting Waxes in Rice Bran Oil: a Case-Study on Berry Wax and Sunflower Wax
Doan, Chi Diem; Tavernier, Iris; Bin Sintang, Mohd Dona et al

in Food Biophysics (2017), 12

Low-melting berry wax (BEW) has proven to be a good oil gelator with a positive contribution to the consistency and flexibility of the structured oil. Nevertheless, the properties of BEWand the ... [more ▼]

Low-melting berry wax (BEW) has proven to be a good oil gelator with a positive contribution to the consistency and flexibility of the structured oil. Nevertheless, the properties of BEWand the corresponding oleogel have not yet been investigated in-depth. In this research, the difference in crystallization and gelling behavior between sunflower wax (SW), a high melting wax, and BEW, a low-melting wax, in rice bran oil (RBO) was investigated. The difference in melting and crystallization temperatures can be explained by the different chemical composition (long-chain wax esters in SWand shortchain fatty acids in BEW). The heterogeneity in crystal habits (unidirectional platelets versus microcrystalline particles) and polymorphism (orthorhombic versus hexagonal) are responsible for the varying gel strength and hardness of the respective SWand BEW-oleogels. The microcrystalline BEW particles aligned and reorganized during 1-month storage at 5 °C, which leaded to an increase in the gel strength and hardness of BEW-oleogel. The gelling property of SW-oleogel however did not significantly differ after 4 weeks at 5 °C, despite of the appearance of spherulitic crystalline clusters. The changes in the physical properties of wax-based oleogels during storage time were further explored using differential scanning calorimetry, polarized light microscope, powder X-ray diffraction and rheology. [less ▲]

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See detailCrystallization and morphologies of waxes in rice bran oil
Diem Doan, Chi; Patel, Ashok R.; Danthine, Sabine ULiege et al

Conference (2016, September)

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See detailCrystallization and polymorphic behavior of enzymatically produced sunflower oil based cocoa butter equivalents
Kadivar, Sheida; De Clercq, Nathalie; Danthine, Sabine ULiege et al

in European Journal of Lipid Science and Technology (2016), 118

A multi-methodological approach was used to study the isothermal crystallization of cocoa butter (CB) in the presence of sunflower oil based cocoa butter equivalents (CBEs). pNMR, DSC, oscillatory ... [more ▼]

A multi-methodological approach was used to study the isothermal crystallization of cocoa butter (CB) in the presence of sunflower oil based cocoa butter equivalents (CBEs). pNMR, DSC, oscillatory rheology, XRD, and PLM were used for this purpose. All the techniques confirmed that at 20°C isothermal crystallization of all the blends is a two-step process with formation of α crystals in the first step and formation of β’ crystals in the second step. The blends with high amount of CBEs contained more high-melting triacylglycerols (TAGs) and diacylglycerol (DAG) in compare with CB acting as seed crystals enhancing the formation of a- crystals in the first crystallization step. Therefore, the induction time of the first crystallization step was inversely related to the amount of CBE. In contrast, the subsequent polymorphic transition was delayed by the presence of the CBE due to their low-melting TAGs. However, adding up to 5% CBE did not change the Foubert’s parameters for isothermal crystallization significantly. All the blends (except 5% HOSO CBE), had a mediated β’ crystallization. Picturing of the microstructure showed that for the CB and the blends up to 50% large microstructures, indicative of the bV polymorph developed during storage. At 100%, a dense network of spherulites was formed at the beginning of the crystallization period, but upon further storage, no large morphological changes were observed. Practical applications: In recent years, the production of CB has been delayed owing to its cultivation difficulty and low yield due to pest attack, while the world cocoa prices have increased with rising demand and higher chocolate consumption. Therefore, there is a need to develop low-priced and appropriate alternatives to CB. Accordingly, in this study two sunflower oil based CBEs were produced with fatty acid mixtures in the presence of immobilized 1,3-regiospecific lipase. The results from this study could help the fats and oils industries to extend their knowledge on the crystallization and polymorphic behavior of two enzymatically produced sunflower oil based CBEs. [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 ULiege 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 ULiege 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 ULiege; 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 ULiege

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 ULiege 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 ULiege; Gerday, Charles ULiege 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 ULiege; 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 behavior of neutralized and bleached shea butter under dynamic conditions
Gibon, V.; Dijckmans, P.; Blecker, Christophe ULiege et al

Poster (2016, May 01)

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