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See detailImportance of structural damping in the dynamic analysis of compliant deployable structures
Dewalque, Florence ULg; Rochus, Pierre ULg; Bruls, Olivier ULg

in Proceedings of the 65th International Astronautical Congress (IAC) (2014)

Compliant mechanisms such as tape springs are often used on satellites to deploy appendices, e.g. solar panels, antennas, telescopes and solar sails. Their main advantage comes from the fact that their ... [more ▼]

Compliant mechanisms such as tape springs are often used on satellites to deploy appendices, e.g. solar panels, antennas, telescopes and solar sails. Their main advantage comes from the fact that their motion results from the elastic deformation of structural components, unlike usual hinges or prismatic joints, the motion of which is dictated by contact surfaces. No actuators or external energy sources are required and the deployment is purely passive, which appears as a decisive feature for the design of low-cost missions with small satellites or cubesats. The mechanical behaviour of a tape spring is intrinsically complex and nonlinear involving buckling, hysteresis and self-locking phenomena. High-fidelity mechanical models are then needed to get a detailed understanding of the deployment process, improve the design and predict the actual behaviour in the space 0-g environment. In the majority of the previous works, dynamic simulations were performed without any physical representation of the structural damping. These simulations could be successfully achieved because of the presence of numerical damping in the transient solver. However, in this case, the dynamic response turns out to be quite sensitive to the amount of numerical dissipation, so that the predictive capabilities of the model are questionable. In this work based on numerical case studies, we show that the dynamic simulation of a tape spring can be made less sensitive to numerical parameters when the structural dissipation is taken into account. [less ▲]

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See detailImportance of surfactin for plant resistance induction by Bacillus isolates
Cawoy, Hélène ULg; Mariutto, Martin; Jourdan, Emmanuel et al

Conference (2012, June 27)

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See detailImportance of synovitis in osteoarthritis: Evidence for the use of glycosaminoglycans against synovial inflammation.
Henrotin, Yves ULg; Lambert, Cécile ULg; Richette, Pascal

in Seminars in Arthritis & Rheumatism (2014), 43(5), 579-87

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See detailImportance of temporal variability for hydrological predictions based on the maximum entropy production principle
Westhoff, Martijn ULg; Zehe, Erwin; Schymanski, Stanislaus J.

in Geophysical Research Letters (2014)

This work builds on earlier work by Kleidon and Schymanski (2008) who explored the use of the maximum entropy production (MEP) principle for modeling hydrological systems. They illustrated that MEP can be ... [more ▼]

This work builds on earlier work by Kleidon and Schymanski (2008) who explored the use of the maximum entropy production (MEP) principle for modeling hydrological systems. They illustrated that MEP can be used to determine the partitioning of soil water into runoff and evaporation—which determines hydroclimatic conditions around the Globe—by optimizing effective soil and canopy conductances in a way to maximize entropy production by these fluxes. In the present study, we show analytically that under their assumption of constant rainfall, the proposed principle always yields an optimum where the two conductances are equal, irrespective of rainfall rate, evaporative demand, or gravitational potential. Subsequently, we show that under periodic forcing or periodic variations in one resistance (e.g., vegetation seasonality), the optimal conductance does depend on climatic drivers such as the length of dry spells or the time of closure of stomata. [less ▲]

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See detailImportance of the alternative pathway of respiration for avoidance of ROS production and for optimisation of photosynthesis in Chlamydomonas
Franck, Fabrice ULg; Dinant, M.; Cardol, Pierre ULg et al

Conference (2008, June)

The physiological function of the alternative pathway of respiration has been investigated by analysing two RNAi C.reinhardtii lines deprived of alternative oxidase protein (AOX1). Compared to wild-type ... [more ▼]

The physiological function of the alternative pathway of respiration has been investigated by analysing two RNAi C.reinhardtii lines deprived of alternative oxidase protein (AOX1). Compared to wild-type, AOX1- lines exhibited modified growth curves and reduced maximal cell density. These differences were more pronounced at high irradiance and in nitrate-containing medium (TAP NO3) rather than in ammonium-containing medium (TAP NH4). Although the alternative pathway was inactive, respiration was not significantly altered in transgenics. Light-saturation curves of O2-evolution were only slightly modified. However, non-photochemical quenching of fluorescence (NPQ) was strongly reduced. Further analysis showed that AOX1- transgenics present a reduced ability to promote the change in energy distribution between photosystems, known as state transition. This effect, which explains low NPQ in the light, was most pronounced in high-light cells cultivated in TAP NO3 medium. Moreover, AOX1- transgenics exhibited higher levels of intracellular peroxides, which suggests that inhibition of state transition might result from higher ROS production. In support of this hypothesis, addition of millimolar-range concentrations of H2O2 to wild-type inhibited the state transition promoted by the reduction of the plastoquinone pool in darkness. [less ▲]

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See detailImportance of the apoprotein in the catalysis of hydroperoxide lyase
Delcarte, J.; Jacques, Philippe ULg; Fauconnier, Marie-Laure ULg et al

Poster (1999, July 15)

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See detailImportance of the conserved residues in the peptidoglycan glycosyltransferase module of the class A penicillin-binding protein 1b of Escherichia coli.
Terrak, Mohammed ULg; Sauvage, Eric ULg; Derouaux, Adeline ULg et al

in Journal of Biological Chemistry (2008), 283(42), 28464-70

The peptidoglycan glycosyltransferase (GT) module of class A penicillin-binding proteins (PBPs) and monofunctional GTs catalyze glycan chain elongation of the bacterial cell wall. These enzymes belong to ... [more ▼]

The peptidoglycan glycosyltransferase (GT) module of class A penicillin-binding proteins (PBPs) and monofunctional GTs catalyze glycan chain elongation of the bacterial cell wall. These enzymes belong to the GT51 family, are characterized by five conserved motifs, and have some fold similarity with the phage lambda lysozyme. In this work, we have systematically modified all the conserved amino acid residues of the GT module of Escherichia coli class A PBP1b by site-directed mutagenesis and determined their importance for the in vivo and in vitro activity and the thermostability of the protein. To get an insight into the GT active site of this paradigm enzyme, a model of PBP1b GT domain was constructed based on the available crystal structures (PDB codes 2OLV and 2OLU). The data show that in addition to the essential glutamate residues Glu233 of motif 1 and Glu290 of motif 3, the residues Phe237 and His240 of motif 1 and Gly264, Thr267, Gln271, and Lys274 of motif 2, all located in the catalytic cavity of the GT domain, are essential for the in vitro enzymatic activity of the PBP1b and for its in vivo functioning. Thus, the first three conserved motifs contain most of the residues that are required for the GT activity of the PBP1b. The residues Asp234, Phe237, His240, Thr267, and Gln271 are proposed to maintain the structure of the active site and the positioning of the catalytic Glu233. [less ▲]

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See detailImportance of the creatinine calibration in the estimation of GFR by MDRD equation
Delanaye, Pierre ULg; Cavalier, Etienne ULg; Chapelle, Jean-Paul ULg et al

in Nephrology Dialysis Transplantation (2006), 21(4), 1130-1130

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See detailImportance of the E-46-D-160 Polypeptide Segment of the Non-Penicillin-Binding Module for the Folding of the Low-Affinity, Multimodular Class B Penicillin-Binding Protein 5 of Enterococcus Hirae
Mollerach, Marta E.; Partoune, Pierre; Coyette, Jacques ULg et al

in Journal of Bacteriology (1996), 178(6), 1774-1775

Compared with the other class B multimodular penicillin- binding proteins (PBPs), the low-affinity PBP5 responsible for penicillin resistance in Enterococcus hirae R40, has an extended non-penicillin ... [more ▼]

Compared with the other class B multimodular penicillin- binding proteins (PBPs), the low-affinity PBP5 responsible for penicillin resistance in Enterococcus hirae R40, has an extended non-penicillin-binding module because of the presence of an approximately 110-amino-acid E-46(-)D-160 insert downstream from the membrane anchor. Expression of pbp5 genes lacking various parts of the insert-encoding region gives rise to proteins that are inert in terms of penicillin binding, showing that during folding of the PBP, the insert plays a role in the acquisition of a correct penicillin-binding configuration by the G-364(-)Q-678 carboxy-terminal module. [less ▲]

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See detailThe importance of the effects of mora debitoris
Cavalleri, Vanessa ULg

Conference (2014, June 19)

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See detailImportance of the enveloppe glycoprotein gp51 in the diagnosis of BLV infection and in the development of an anti-BLV subunit vaccine.
Portetelle, Daniel ULg; Dandoy, Corinne; Gras, Hélène et al

in Journal of Cellular Biochemistry. Supplement (1986), (suppl 10 A), 209

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See detailImportance of the His-298 Residue in the Catalytic Mechanism of the Streptomyces R61 Extracellular Dd-Peptidase
Hadonou, Ayaovi M.; Jamin, Marc; Adam, Maggy et al

in Biochemical Journal (1992), 282(Pt 2), 495-500

Among the active-site-serine penicillin-recognizing proteins, the Streptomyces R61 extracellular DD-peptidase is the only one to have a His-Thr-Gly sequence [instead of Lys-Thr(Ser)-Gly] in 'box' VII. The ... [more ▼]

Among the active-site-serine penicillin-recognizing proteins, the Streptomyces R61 extracellular DD-peptidase is the only one to have a His-Thr-Gly sequence [instead of Lys-Thr(Ser)-Gly] in 'box' VII. The His residue was replaced by Gln or Lys. Both mutations induced a marked decrease in the rates of both tripeptide substrate hydrolysis and acylation by benzylpenicillin and cephalosporin C. The rate of hydrolysis of the thioester hippuryl thioglycollate was less affected. The most striking result was the disproportionate loss of transpeptidation properties by both mutants, indicating an important role of His-298 in this reaction. We believe that this result represents the first modification of a DD-peptidase leading to a specific decrease of the transpeptidation-to-hydrolysis ratio. [less ▲]

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See detailImportance Of The Hydrophobic Energy: Structural Determination Of A Hypoglycemic Drug Of The Meglitinide Family By Nuclear Magnetic Resonance And Molecular Modeling
Lins, Laurence ULg; Brasseur, Robert ULg; Malaisse, Wj. et al

in Biochemical Pharmacology (1996), 52(8), 1155-68

The molecular structure of (2S)-2-benzyl-3-(cis-hexahydro-2-isoindolinylcarbonyl) propionic acid (KAD-1229), a hypoglycemic drug of the meglitinide family, was studied by nuclear magnetic resonance (NMR ... [more ▼]

The molecular structure of (2S)-2-benzyl-3-(cis-hexahydro-2-isoindolinylcarbonyl) propionic acid (KAD-1229), a hypoglycemic drug of the meglitinide family, was studied by nuclear magnetic resonance (NMR) and molecular modeling. The results of the NMR experiments indicated that KAD-1229 existed in solution in the form of two stable conformers of equal population, called KADI and KADII in this paper. Three different molecular modelings were then applied: the classical molecular dynamics using the commercial Biosym and Hyperchem softwares and the Prot+ program, which is not based on a dynamical study but on a systematic conformational analysis of the molecule, which includes a term that allows the estimation of the hydrophobic interaction. The modeling results showed the following points. First, in contrast with classical molecular dynamics, which uses restraints from two-dimensional nuclear Overhauser effect (NOE) data, the Prot+ KAD structure provides conformations that support experimental NMR data without any external intervention. In the structures in agreement with NMR data, an important hydrophobic interaction between the phenyl cycle and the perhydroisoindole ring of KAD is observed. This interaction, which seems to play a role in the biological activity of the drug, is lost when no restraints are considered in classical molecular dynamics. Second, the difference between KADI and KADII arises mainly from slight distance geometric differences at the level of the perhydroisoindole and the phenyl rings. [less ▲]

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See detailImportance of the microbenthic loop of Posidonia oceanica meadows to detect anthropogenic perturbations early: first results
Pete, Dorothée ULg; Velimirov, Branko; Bouquegneau, Jean-Marie ULg et al

Conference (2008, August)

It was demonstrated that Posidonia oceanica, the marine magnoliophyte endemic to the Mediterranean Sea, is a valuable tool to assess environmental qualities of the coastal zones. However, only few studies ... [more ▼]

It was demonstrated that Posidonia oceanica, the marine magnoliophyte endemic to the Mediterranean Sea, is a valuable tool to assess environmental qualities of the coastal zones. However, only few studies have attempted to use characteristics of its sediment compartment as an indicator of the environment state of health. Yet, organisms living in this compartment have a turnover which is faster than for canopy-organisms which makes them useful as valid early descriptors of pollution. The study described here takes place in a project which aims to find an early holistic indicator of anthropogenic perturbations in the Mediterranean coastal zones. The investigation is based on the microbenthic loop (organic matter, bacteria, microphytobenthos and meiofauna) and was led in two different sites of Calvi Bay (Corsica, France), at 10 m depth, in March and June 2007. Only results about bacteria (abundance, biomass, morphotypes), microphytobenthos (biomass) and organic matter (biomass) will be presented. For both seasons, significant differences between sites are found, irrespective on whether variables are treated separately or together, thus indicating that the microbenthic loop has potential to be a good early indicator of pollution. [less ▲]

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See detailThe Importance of the Negative Charge of Beta-Lactam Compounds in the Interactions with Active-Site Serine Dd-Peptidases and Beta-Lactamases
Varetto, Louis ULg; De Meester, Fabien; Monnaie, Didier et al

in Biochemical Journal (1991), 278(Pt 3), 801-807

The interaction between various penicillins and cephalosporins the carboxylate group of which at C-3 or C-4 had been esterified or amidated and different penicillin-recognizing enzymes was studied. In ... [more ▼]

The interaction between various penicillins and cephalosporins the carboxylate group of which at C-3 or C-4 had been esterified or amidated and different penicillin-recognizing enzymes was studied. In general, our findings reinforced the common assumption that an anionic group at that position is necessary for the effective acylation of these enzymes. However, the relative activities of the modified beta-lactams as inactivators of the Streptomyces R61 DD-peptidase or as substrates of the Bacillus licheniformis, Streptomyces albus G and Enterobacter cloacae beta-lactamases did not fit a general scheme in which the intrinsic electronic and geometric properties of the beta-lactam compounds would be sufficient to explain their substrate or inactivator properties towards the various types of enzymes investigated. [less ▲]

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See detailThe importance of the negative charge of β-lactam compounds for the inactivation of the active-site serine DD-peptidase of Streptomyces R61
Varetto, Louis ULg; Frère, Jean-Marie ULg; Ghuysen, Jean-Marie ULg

in FEBS Letters (1987), 225(1-2), 218-222

The interaction between the Streptomyces R61 penicillin-sensitive DD-peptidase and deacetyl-cephalosporin C or its lactone derivative has been studied at different pH values. The results show the ... [more ▼]

The interaction between the Streptomyces R61 penicillin-sensitive DD-peptidase and deacetyl-cephalosporin C or its lactone derivative has been studied at different pH values. The results show the importance of an enzyme group of pK approximately equal to 9 which might form an ion pair with the free carboxylate of the former compound. This electrostatic interaction is shown to contribute to the formation of the first, non-covalent enzyme-inactivator complex by a factor of at least 50. [less ▲]

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See detailImportance of the PIKKs in NF-kappaB activation by genotoxic stress
Sabatel, Hélène ULg; Pirlot, Céline ULg; Piette, Jacques ULg et al

in Biochemical Pharmacology (2011), 82(10), 1371-83

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See detailImportance of the Two Tryptophan Residues in the Streptomyces R61 Exocellular Dd-Peptidase
Bourguignon-Bellefroid, Catherine; Wilkin, Jean-Marc; Joris, Bernard ULg et al

in Biochemical Journal (1992), 282(Pt 2), 361-367

Modification of the Streptomyces R61 DD-peptidase by N-bromosuccinimide resulted in a rapid loss of enzyme activity. In consequence, the role of the enzyme's two tryptophan residues was investigated by ... [more ▼]

Modification of the Streptomyces R61 DD-peptidase by N-bromosuccinimide resulted in a rapid loss of enzyme activity. In consequence, the role of the enzyme's two tryptophan residues was investigated by site-directed mutagenesis. Trp271 was replaced by Leu. The modification yielded a stable enzyme whose structural and catalytic properties were similar to those of the wild-type protein. Thus the Trp271 residue, though almost invariant among the beta-lactamases of classes A and C and the low-Mr penicillin-binding proteins, did not appear to be essential for enzyme activity. Mutations of the Trp233 into Leu and Ser strongly decreased the enzymic activity, the affinity for beta-lactams and the protein stability. Surprisingly, the benzylpenicilloyl-(W233L)enzyme deacylated at least 300-fold more quickly than the corresponding acyl-enzyme formed with the wild-type protein and gave rise to benzylpenicilloate instead of phenylacetylglycine. This mutant DD-peptidase thus behaved as a weak beta-lactamase. [less ▲]

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