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See detailDesign of a single-species biofilm reactor based on metal structured packing for the production of high added value biomolecules
Zune, Quentin ULg

Doctoral thesis (2015)

Thesis summary In the last decade, numerous single-species biofilm reactors of various configurations have been implemented at lab and pilot scale for the production of chemicals and biological products ... [more ▼]

Thesis summary In the last decade, numerous single-species biofilm reactors of various configurations have been implemented at lab and pilot scale for the production of chemicals and biological products. Compared to their counterparts in submerged cultures, these processes benefit from the specific physiology of biofilms, i.e. high robustness of the microbial system, long-term activity, continuous implementation and low ratio size / productivity. However, the risks of biofouling and the lack of analytical tools for the control and the monitoring of biofilms are obstacles for scale-up strategies. Up to now, single-species biofilm reactors have been mainly confined to the production of metabolites ranging from low (bulk chemicals) to medium (fine chemicals) added values. In this way, there is a need to design efficient single-species biofilm reactors exhibiting good scalability potentials and intended for the production of high added value compounds. In this work, an experimental single-species biofilm reactor has been designed for the production of target molecules derived from metabolic pathways involved in biofilm physiology. On the basis of these criteria, three biological models having good abilities of biofilm formation and secretion performances were selected : - the gram positive bacterium Bacillus subtilis for the production of surfactin, a surface active metabolite involved in biofilm formation. - the filamentous fungus Trichoderma reesei for the production of hydrophobin (HFBII), a surface active protein (7kDa) involved in adhesion process of spores and mycelium on solid surface. - the filamentous fungus Aspergillus oryaze (engineered strain) for the production of a recombinant protein (Gla::GFP) under the control of the glaB promoter specifically activated in solid-state fermentation. The proposed experimental biofilm reactor has the configuration of a trickle-bed bioreactor. The agitation axis of a stirred tank reactor has been removed and replaced by a stainless steel structured packing filling the top of the vessel. The liquid medium, located in the bottom of the vessel is continuously recirculated on the packing element thanks to a peristaltic pump. An ascending air flow is performed above the liquid phase just under the packing element. This thesis reports the screening of the three biological models in the experimental biofilm reactor. The results include the characterization of process performances in terms of biofilm formation and secretion of the target molecule under different operating conditions. An original methodology based on high energy X-ray tomography has been developed to non-invasively visualize and quantify the biofilm colonization inside the packing element. This technique has highlighted that biofilm colonization and liquid phase distribution across the packing are strongly interrelated phenomena. The biofilm of B. subtilis occurring by cell aggregation preferentially developed on solid areas wetted by the liquid. Accordingly, optimal operating conditions improving liquid phase distribution have been defined for biofilm colonization. The fungal biofilm of A. oryzae and T. reesei occuring by cell filamentation equally colonize submerged and aerial surfaces of the packing element. Consequently, another configuration of biofilm reactor comprising a packing element totally immersed in the liquid medium has been investigated. The production yields of surfactin and hydrophobin in the experimental biofilm reactor are respectively 1.25 and 2.64 times greater than those of a submerged culture in a stirred tank reactor. This suggests that surface-active molecules involved in biofilm formation have a real interest for the design of single-species biofilm reactors. Although the Gla::GFP fusion protein is greater produced in the stirred tank culture, its integrity was preserved in the biofilm reactor despite the presence of proteases. This suggests that the quality and the stability of heterologous proteins produced in a fungal biofilm reactor are improved compared with a submerged culture. Finally, the implementation of the biofilm reactor has led to technological progresses including low energy consumption, no foam formation, continuous processing and simplification of downstream process operations. Further experiments should deepen the understanding of structured phenotypic heterogeneity impact on secretion performances in the biofilm reactor. These experiments should consider development of operating conditions allowing for the growth of a thin biofilm homogeneously distributed on the whole surface provided by the packing element in order to optimize nutrients and metabolites mass transfers. The scale-up and the continuous implementation of the process should be also investigated. [less ▲]

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See detailRegulation of Tissue Factor by Epithelial-to-Mesenchymal Transitions: Impacts for the metastatic progression.
Francart; Bourcy, M; Suarez-Carmona, M et al

Poster (2015, December 03)

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See detailThe role of companies in « smart and sustainable city » initiatives in Belgium
André, Anne-Marie; Crutzen, Nathalie ULg

Report (2015)

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See detailRoot-emitted volatile organic compounds in belowground plant-plant interactions
Delory, Benjamin ULg

Doctoral thesis (2015)

Plants are able to synthesise and release volatile organic compounds (VOCs) aboveground (leaves, stems, flowers and fruits) and belowground (roots). Once emitted, these molecules are key mediators in ... [more ▼]

Plants are able to synthesise and release volatile organic compounds (VOCs) aboveground (leaves, stems, flowers and fruits) and belowground (roots). Once emitted, these molecules are key mediators in biotic interactions as they can be perceived by plant neighbours (first trophic level) and are able to attract/repel organisms of the second (insect herbivores, plant parasitic nematodes) or the third trophic level (entomopathogenic nematodes, parasitoids, etc.). Although many laboratory and field experiments have focused on VOC-mediated plant-plant interactions aboveground, less is known regarding the roles played by root-emitted VOCs in between- and within-plant signalling. In this context, the main goals of this PhD thesis were to (1) identify and quantify the VOCs emitted by barley and chamomile roots and (2) study the influence of chamomile root volatiles on the growth (biomass production and allocation) and the root system architecture (RSA) of barley (interspecific model). Root-emitted VOCs were analysed without extracting the roots from the soil (in situ) using a three-step gas chromatography-mass spectrometry methodology. Plant-plant interaction bioassays were performed using an original experimental device allowing the controlled exposition of growing barley roots to the volatile compounds emitted by chamomile roots for 15 days. In order to speed up the RSA analysis of recipient barley plants, we developed an R package (archiDART) allowing (1) the batch processing of the raw data exported by Data Analysis of Root Tracings (DART) and root image analysis software tools supporting the Root System Markup Language (RSML) format, and (2) the automated computation of RSA traits. Our results showed that crushed barley roots produced mainly hexanal, (E)-hex-2-enal, (E)-non-2-enal and (E,Z)-nona-2,6-dienal. Three-day-old seminal roots were characterised by higher total and individual VOC concentrations compared with older phenological stages. Our experiments also showed that enzymatic activities were required for volatile production. For each developmental stage, the lipoxygenase (LOX) specificity was greater for linoleic acid than for α-linolenic acid. The greatest LOX activities using linoleic and α-linolenic acids as substrates were measured in 7- and 3-day-old roots, respectively. Although undamaged barley roots did not release detectable amounts of VOCs, the analysis of VOCs emitted by mechanically injured roots showed that (E)-non-2-enal (13.8 ± 4.9 ng/g dry wt/h) and (E,Z)-nona-2,6-dienal (4.7 ± 1.8 ng/g dry wt/h) were the only VOCs detected in the plant rhizosphere. Contrasting with these results, the undamaged roots of 61- to 78-day-old chamomile plantlets released mainly one trinorsesquiterpene (albene) and four tricyclic sesquiterpene hydrocarbons (silphinene, modheph-2-ene, α-isocomene and β-isocomene) associated with the Asteraceae family. For each sesquiterpene hydrocarbon, the emission rate was positively correlated with plant age. Based on these results, we performed plant-plant interaction bioassays to investigate the roles played by chamomile root volatiles on the growth and RSA of barley. After 15 days of exposure, plants exposed to the volatiles emitted by the soil and chamomile roots or by the soil alone (control) were morphologically similar. Although not statistically significant (P < 0.09), the leaf area and the total seminal root length were the only parameters that tended to be greater in plants that received the volatile compounds emitted by chamomile roots compared with control plantlets. All these results are discussed in the context of belowground chemical ecology. In addition, some improvements of the experimental devices developed in this research project are also suggested at the end of this PhD thesis. [less ▲]

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See detailEvolution of the Northern Rockweed, Fucus distichus, in a Regime of Glacial Cycling: Implications for Benthic Algal Phylogenetics
Laughinghouse, Haywood, Dail; Müller, Kirsten; Adey, Walter et al

in PLoS ONE (2015), 10(12), 0143795

Northern hemisphere rockweeds (Fucus) are thought to have evolved in the North Pacific and then spread to the North Atlantic following the opening of the Bering Strait. They have dispersed and widely ... [more ▼]

Northern hemisphere rockweeds (Fucus) are thought to have evolved in the North Pacific and then spread to the North Atlantic following the opening of the Bering Strait. They have dispersed and widely speciated in the North Atlantic and its tributary seas. Fucus distichus is likely near the ancestral member of this genus, and studies have shown that there are several species/subspecies in this complex (i.e. F. evanescens and F. gardneri). We used phylogenetic and haplotype analyses to test the phylogenetic relationships and biogeogra- phy of F. distichus. Our data and subsequent analyses demonstrate that, unlike previous studies that lacked samples from an extensive geographical area of the Arctic and Subarc- tic, there is a distinct Arctic haplotype that is the source of subspecies in both the North Pacific and North Atlantic. Fucus distichus occupies a low tide zone habitat, and in Arctic/ Subarctic regions it is adapted to the severe stress of sea ice coverage and disturbance dur- ing many months per year. We hypothesize that the very large geographic area of Arctic and Subarctic rocky shores available to this species during interglacials, supported by large Arctic/Subarctic fringe areas as well as unglaciated refugia during glacial cycles, provided a robust population and gene pool (described by the Thermogeographic Model). This gene pool dilutes that of the more fragmented and area-limited Temperate/Boreal area popula- tions when they are brought together during glacial cycles. We suggest that similar subspe- cies complexes for a variety of Arctic/Subarctic shore biota should be examined further in this context, rather than arbitrarily being split up into numerous species. [less ▲]

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See detailLa transmission des concepts. Étude de cas : intensité vs extensité
Badir, Sémir ULg

Scientific conference (2015, December 02)

L’étude des idées compte parmi les exercices les plus fréquentés du discours critique en histoire des sciences humaines. Mais il semble que cette étude soit menée généralement en suivant une tradition du ... [more ▼]

L’étude des idées compte parmi les exercices les plus fréquentés du discours critique en histoire des sciences humaines. Mais il semble que cette étude soit menée généralement en suivant une tradition du commentaire littéraire et philosophique antérieure aux apports théoriques et méthodologiques dus aux recherches sémio-linguistiques. Apports quant aux moyens (analyse microsémantique, médiations rhétoriques, marques énonciatives…), permettant de formuler des exigences épistémologiques supplémentaires (relatives au statut différentiel et structurel des concepts, au dédoublement des chaînes intertextuelles à suivre pour les concepts étudiés et pour les termes qui les expriment) à l’horizon d’une théorie de la connaissance qui ne compterait pas pour rien la fonction fondamentale de la transmission. Dans la présente intervention, on prendra pour cas d’étude la filiation conceptuelle du couple intensité vs extensité proposé par Claude Zilberberg à partir, notamment, des concepts intensif et extensif dus à Louis Hjelmslev, en cherchant à mettre en relief les questions et enjeux que les apports sémio-linguistiques permettent de formuler. [less ▲]

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See detailEstimation de spectres de singularités par des méthodes de grandes déviations basées sur les ondelettes
Esser, Céline ULg

Scientific conference (2015, December 02)

La régularité d'un signal en un point peut être caractérisée par son exposant de Hölder. Une description synthétique de la répartition des différents exposants de Hölder d'un signal est fournie par son ... [more ▼]

La régularité d'un signal en un point peut être caractérisée par son exposant de Hölder. Une description synthétique de la répartition des différents exposants de Hölder d'un signal est fournie par son spectre de singularités. Plusieurs méthodes basées sur la décomposition en ondelettes ont été proposées pour estimer le spectre de singularités d'un signal; elles reposent sur une caractérisation de l'exposant de Hölder par les coefficients d'ondelettes. Dans cet exposé, nous présentons une nouvelle méthode reposant sur des estimations de grandes déviations basées sur les coefficients d'ondelettes et montrons son efficacité sur plusieurs exemples déterministes ou non. [less ▲]

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See detailEstimation de la quantité de matière sèche ingérée par les vaches laitières au pâturage en traite robotisée, utilisation de l’analyse des fèces en spectrométrie dans le proche infrarouge
Lessire, Françoise ULg; Dufrasne, Isabelle ULg; Decruyenaere, Virginie

in Agabriel, Jacques; Boichard, Didier; Choisis, Jean-Philippe (Eds.) et al 22èmes Rencontres autour des recherches sur les ruminants. (2015, December 02)

Malgré l’intérêt nutritionnel et économique de l’herbe dans la ration des vaches laitières, le pâturage est de plus en plus délaissé en raison notamment de l’automatisation de la traite et de l’extension ... [more ▼]

Malgré l’intérêt nutritionnel et économique de l’herbe dans la ration des vaches laitières, le pâturage est de plus en plus délaissé en raison notamment de l’automatisation de la traite et de l’extension de la taille des troupeaux. Une des raisons invoquées par les éleveurs pour cet abandon est leur manque de confiance par rapport aux quantités d’herbe réellement ingérées par les animaux et la crainte que ces apports inconstants se traduisent par des fluctuations de production laitière tant qualitative que quantitative. Or Decruyenaere et al. (2009, 2012) ont développé une méthode d’estimation de la matière sèche volontairement ingérée (MSVI) par analyse des bouses par spectrométrie dans le proche infra-rouge. Cette méthode présente l’avantage d’être non invasive, facile à mettre en œuvre sur le terrain et peu onéreuse. Le but de cette étude était donc d’évaluer l’utilisation de cette méthode dans un troupeau de vaches laitières traites par un robot mobile en pâture. Le troupeau (n=53) était divisé en 2 groupes dont le niveau de complémentation journalière était différent. Lors de la traite, le groupe 1 (GR1) recevait en moyenne 2,6 kg de concentrés/vache alors que le groupe 2 (GR2) en recevait 4,2 kg/vache. L’objectif était de vérifier l’impact du niveau de complémentation sur les résultats obtenus. Des prélèvements de fèces ont été faits une fois par mois sur 10 vaches (5 vaches par groupe) pendant 4 mois. Les spectres d’absorption dans le proche infra-rouge (NIR) ont été confrontés à des étalonnages NIR permettant l’estimation de la MSVI exprimée soit par rapport au poids vif (MSVI1), soit par rapport au poids métabolique (MSVI2). Ces estimations d’ingestion ont permis le calcul de la matière sèche journalière ingérée par vache (MSI1 et MSI2). Par ailleurs, les mesures d’herbe à l’entrée et à la sortie des parcelles pâturées ont été relevées ainsi que la densité du couvert herbacé pour évaluer la quantité d’herbe disponible. A ces valeurs de biomasses disponibles ont été additionnées des quantités de concentrés distribuées lors du passage des animaux au robot. Les valeurs moyennes de matière sèche ingérée (kg/vache/jour) pour le GR1 étaient de 15,20 ± 2,60 kg MS par la MSI1 et de 16,99 ± 1,80 kg MS pour la MSI2. Pour le GR2, la MSI1moyenne était de 20,20 ± 4,95 kg MS et la MSI2 moyenne de 21,95 ± 3,36 kg MS. L’estimation de la ration disponible par vache (kg MS herbe + kg MS concentrés) était de 17,25 ± 0,73 kg MS pour le GR1 et de 18,69 ±0,83 kg MS pour le GR2. Les valeurs obtenues par l’analyse NIR sont donc compatibles avec les quantités d’herbe et de concentrés disponibles. Les valeurs estimées par les 2 méthodes étaient hautement corrélées entre elles à part en période de faible ingestion (<10 kgMS). En ce cas la MSI2 semble donner des résultats plus fiables. En conclusion, l’analyse NIR des bouses apparaît une technique intéressante pour l’estimation de la quantité d’herbe ingérée au pâturage. [less ▲]

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See detailSynthesis of functional polyphosphates for hydrogel and particle drug delivery systems
Vanslambrouck, Stéphanie; Ergül, Zeynep ULg; Clément, Benoit et al

Conference (2015, December 02)

Thanks to their biocompatibility and degradability properties, polyphosphates are appealing polymers for biomedical applications. In contrast to aliphatic polyesters, such as poly(ε-caprolactone) and poly ... [more ▼]

Thanks to their biocompatibility and degradability properties, polyphosphates are appealing polymers for biomedical applications. In contrast to aliphatic polyesters, such as poly(ε-caprolactone) and poly(lactide), the pentavalency of the phosphorus atom allows the easy modification of the polyphosphate properties by simply adjusting the nature, the length and the functionality of the polyphosphate pendant groups. Macromolecular engineering of polyphosphoesters was applied to design well-defined architectures and functionalities adapted to drug nanocarriers. In a first approach, amphiphilic block copolymers are synthesized by organo-catalyzed ring-opening polymerization process for the synthesis of a range of PEO-b-polyphosphate bearing various pendant groups. Post-polymerization thiol-ene click reactions preformed on PEO-b-polyphosphate copolymers was also investigated to improve the hydrophobicity of the polyphosphate. The self-assembly of these PEO-b-polyphosphate copolymers into micelles was investigated, particularly, the effect of the nature of the polyphosphate pendant groups (i) on the micelles characteristics, (ii) on the encapsulation of a poorly soluble drug and (iii) on the drug release profile. The toxicity of the different amphiphilic block copolymers was also evaluated by live/dead cell viability assays. In a second approach, double hydrophilic copolymers based on polyphosphoesters have been used as templating agent for the synthesis of calcium carbonate particles. Indeed, the use of such microparticles is becoming more and more attractive in many fields especially for biomedical applications for which fine tuning of size, morphology and crystalline form of CaCO3 particles is crucial. Although some structuring compounds, like hyaluronic acid, give satisfying results, the control of the particle structure still has to be improved. To this end, we evaluated the CaCO3 structuring capacity of the well-defined double hydrophilic block copolymers composed of poly(ethylene oxide) and of a polyphosphoester segment with affinity for calcium like poly(phosphotriester)s bearing pendant carboxylic acids or poly(phosphodiester)s with a negatively charged oxygen atom on each repeating monomer unit. [less ▲]

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See detailAnalytical Tools and Strategic Approach to Detect Poor Quality Medicines, Identify Unknown Components, and Timely Alerts for Appropriate Measures: Case Study of Antimalarial Medicines
Habyalimana, Védaste ULg; Mbinze Kindenge, Jérémie; Kalenda Tshilombo, Nicodème ULg et al

in American Journal of Analytical Chemistry (2015), 6

Nowadays, the circulation of poor quality medicines is becoming an alarming worldwide phenomenon with serious public health and socio-economic concerns. The situation is particularly critical in ... [more ▼]

Nowadays, the circulation of poor quality medicines is becoming an alarming worldwide phenomenon with serious public health and socio-economic concerns. The situation is particularly critical in developing countries where drug quality assurance and regulatory systems for drug manufacturing, importation, distribution and sales are weak. A sustained vigilance on poor quality medicines that regroup counterfeit/falsified, substandard and degraded medicines is therefore required to ensure patient safety and genuine medicines integrity. A case situation is illustrated including a strategic approach and analytical tools that were found useful to detect poor quality medicines, identify unknown components, and timely alerts for appropriate measures against the spread of those harmful products. Several suspected medicines randomly sampled in several strategic Rwandan areas were firstly check-controlled by means of visual inspection and then applying several analytical techniques from simple to more complex ones. The following medicines were studied: quinine sulfate tablets, artemisinin-based combination tablets, and artesunate powders for injection. Taking into account the pharmaceutical forms and the chemical characteristics, the following tests were applied: uniformity of mass, friability, disintegration, fluorescence, identification and assay. They were followed by more complex analytical techniques that allowed more comprehension of abnormal findings among which the presence of a wrong active pharmaceutical ingredient in quinine sulfate tablets which is mainly discussed in this paper to illustrate a strategic approach and various analytical tools that can be used in detecting and identifying unknown component in poor quality medicines. [less ▲]

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See detailNeuropathies périphériques (patho)
WANG, François-Charles ULg

Learning material (2015)

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See detailAn overview of recent IUVS periapse MUV observations
Stiepen, Arnaud ULg

Conference (2015, December 01)

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See detailLes lieux d’habitation des écrivains belges francophones à Bruxelles (1930-1960). Premiers jalons pour une histoire sociogéographique
Debroux, Tatiana; Vanderpelen-Diagre, Cécile; Dozo, Björn-Olav ULg

in Textyles : Revue des Lettres Belges de Langue Française (2015), 47

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See detailNo favorable effect of reduced tillage on microbial communities in a silty loam soil (Belgium)
Degrune, Florine ULg; Theodorakopoulos, Nicolas ULg; Dufrêne, Marc ULg et al

Poster (2015, December 01)

To date, only a few studies have applied metagenomics to investigate the influence of different tillage regimes and types of crop residue management on soil microbial communities. These studies were ... [more ▼]

To date, only a few studies have applied metagenomics to investigate the influence of different tillage regimes and types of crop residue management on soil microbial communities. These studies were conducted under specific climates on soils characterized by particular land-use histories. A very different ecological context is to be found in certain areas of Western Europe, such as central Belgium, whose loess-derived soils are among the most fertile in the world and have long been used for intensive agriculture. Specific objectives were to determine diversity levels and changes in microbial community composition under different combinations of tillage regime (conventional vs. reduced) and crop residue fate (residue removal R- vs. residues left R+ on the field). As reduced tillage results in two contrasting zones (the first centimeters of soil are mixed each year, while the soil below remains unperturbed), we chose to perform the analysis at two depths: 0 to 5 cm and 15 to 20 cm. [less ▲]

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See detailTRAPPIST photometry and imaging monitoring of comet C/2013 R1 (Lovejoy): Implications for the origin of daughter species
Opitom, Cyrielle ULg; Jehin, Emmanuel ULg; Manfroid, Jean ULg et al

in Astronomy and Astrophysics (2015), 584

We report the results of the narrow-band photometry and imaging monitoring of comet C/2013 R1 (Lovejoy) with the robotic telescope TRAPPIST (La Silla observatory). We gathered around 400 images over 8 ... [more ▼]

We report the results of the narrow-band photometry and imaging monitoring of comet C/2013 R1 (Lovejoy) with the robotic telescope TRAPPIST (La Silla observatory). We gathered around 400 images over 8 months pre- and post-perihelion between September 12, 2013 and July 6, 2014. We followed the evolution of the OH, NH, CN, C[SUB]3[/SUB], and C[SUB]2[/SUB] production rates computed with the Haser model, as well as the evolution of the dust production. All five gas species display an asymmetry about perihelion, since the rate of brightening is steeper than the rate of fading. The study of the coma morphology reveals gas and dust jets that indicate one or several active zone(s) on the nucleus. The dust, C[SUB]2[/SUB], and C[SUB]3[/SUB] morphologies present some similarities, while the CN morphology is different. OH and NH are enhanced in the tail direction. The study of the evolution of the comet activity shows that the OH, NH, and C[SUB]2[/SUB] production rate evolution with the heliocentric distance is correlated to the dust evolution. The CN and, to a lesser extent, the C[SUB]3[/SUB] do not display such a correlation with the dust. This evidence and the comparison with parent species production rates indicate that C[SUB]2[/SUB] and C[SUB]3[/SUB], on one hand, and OH and NH, on the other, could be - at least partially - released from organic - rich grains and icy grains. On the contrary, all evidences point to HCN being the main parent of CN in this comet. [less ▲]

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See detailKroniek van het Nederlandse nationaliteitsrecht 2014-2015
Vonk, Olivier ULg

in Asiel- en Migrantenrecht (2015)

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See detailProtein structure modeling using backbone chemical shifts
Wanko Nembot, Alexis Marius ULg; Damblon, Christian ULg

Poster (2015, December 01)

The knowledge of the tridimensional structure of a protein is essential to study its interactions and understand its mode of action. The Purpose of our work is to quickly and easily determine the ... [more ▼]

The knowledge of the tridimensional structure of a protein is essential to study its interactions and understand its mode of action. The Purpose of our work is to quickly and easily determine the structure of proteins using the backbone chemical shifts. Backbone chemical shifts data are NMR parameters that can be rapidly, easily and accurately measured. This parameter is very sensitive to the conformation of amino acids and is used to deduct the secondary structure (TALOS, RCI,...). We therefore plan to use backbone chemical shifts as constraints on dihedral angles to quickly and easily determine protein structure. Several « de novo » methods like CS-Rosetta , CS23D et CHESHIRE have been recently developed in this purpose. We will use proteins of different sizes for which, the structure (X-ray or NMR structure) and chemical shifts backbone are available for testing the three softwares. Knowing that each of these softwares predicted a large number of low energy models on the one hand, and that the deployment and use of these tools constitutes obstacles for users who are not experts in computer science on the other hand, our goal will be to develop a platform that can easily compare these three methods based on quality of the structure produced. [less ▲]

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