References of "De Pauw, Edwin"
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See detailStructural analysis of monometallic ruthenium–arene complexes using ion mobility mass spectrometry, collision-induced dissociation, and density functional theory
Cserwinska, Izabella; Far, Johann ULg; Kune, Christopher ULg et al

in Journal of the Chemical Society. Dalton Transactions (in press)

Ion mobility mass spectrometry (IM-MS) and collision-induced dissociation (CID) techniques were used to investigate the influence of the phosphine ligand on the physicochemical properties of [RuCl2(p ... [more ▼]

Ion mobility mass spectrometry (IM-MS) and collision-induced dissociation (CID) techniques were used to investigate the influence of the phosphine ligand on the physicochemical properties of [RuCl2(p-cymene)(PCy3)] (1), [RuCl2(p-cymene)-(PPh3)] (2), and [RuCl2(p-cymene)(PTA)] (3) in the gas phase (PTA is 1,3,5-triaza-7-phosphaadamantane). Electrospray ionization of complexes 1 and 2 led to the corresponding [RuCl(p-cymene)(PR3)]+ ions via the dissociation of a chlorido ligand, whereas RAPTA-C (3) afforded two molecular ions by in-source oxidation ([RuIIICl2(p-cymene)(PTA)]+) or protonation ([RuCl2(p-cymene)(PTA+H)]+). Control experiments showed that the balance between these two ionization paths was strongly influenced by the nature of the solvent used for infusion. Collision cross sections (CCSs) of the four molecular ions accurately reflected the variations of steric bulk inferred from the Tolman steric parameters (θ) of the phosphine ligands. Moreover, DFT calculations combined with a model based on the kinetic theory of gases (the trajectory method of the IMoS software) afforded reliable CCS predictions. The almost two times higher dipole moment of [RuCl2(p-cymene)-(PTA+H)]+ (μ = 13.75 D) compared to [RuIIICl2(p-cymene)(PTA)]+ (μ = 7.18 D) was held responsible for increased ion-induced dipole interactions with a polarizable drift gas such as N2. Further experiments with He and CO2 confirmed that increasing the polarizability of the buffer gas improved the separation between the two molecular ions derived from complex 3. The fragmentation patterns of complexes 1–3 were determined by CID. The sequence of collision voltages at which 50% of a precursor ion dissociates (V50) recorded for the molecular ions derived from compounds 1–3 was in good agreement with simple electronic considerations based on the donor strength of the phosphine ligand. Thus, the CCS and V50 parameters used to determine the shape and stability of ionic species in the gas phase are complementary to the Tolman steric and electronic parameters (θ and TEP) commonly used by organometallic chemists in condensed phases. [less ▲]

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See detailMass-spectrometry-based method for screening of new peptide ligands for G-protein-coupled receptors
Cologna Takeno, Camila; Gilles, Nicolas; Echterbille, Julien ULg et al

in Analytical and Bioanalytical Chemistry (in press)

G-protein-coupled receptors (GPCRs) constitute the largest family of transmembrane proteins. Although implicated in almost all physiological processes in the human body, most of them remain unexploited ... [more ▼]

G-protein-coupled receptors (GPCRs) constitute the largest family of transmembrane proteins. Although implicated in almost all physiological processes in the human body, most of them remain unexploited, mostly because of the lack of specific ligands. The objective of this work is to develop a new mass-spectrometry-based technique capable of identifying new peptide ligands for GPCRs. The strategy is based on the incubation of cellular membranes overexpressing GPCRs with a mixture of peptides that contains potential ligands. Peptide ligands bind to the receptors, whereas other peptides remain in the binding buffer. Bound peptides are eluted from membranes and directly detected, identified, and characterized by MALDI TOF–TOF. The results reveal the efficacy of the procedure for selecting a specific ligand of GPCRs in both simple and complex mixtures of peptides. This new approach may offer direct purification, identification, and characterization of the new ligand in a single workflow. The proposed method is labeling-free and, unlike radio-binding and other techniques, it does not require a previously known labeled ligand of the studied GPCR. All these properties greatly reduce the experimental constraints. Moreover, because it is not based on the principle of a competitive specific binding, this technique constitutes a new tool to discover new ligands not only for known GPCRs, but also for orphan GPCRs [less ▲]

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See detailFrom Valeriana officinalis to cancer therapy: the success of a bio-sourced compound
Hamaïdia, Malik ULg; Barez, Pierre-Yves ULg; Carpentier, Alexandre ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2016), 20

Over the centuries, bio-sourced compounds isolated from plants, insects and microorganisms have been a potent source of drugs for the treatment of human diseases. In this review, we recapitulate the story ... [more ▼]

Over the centuries, bio-sourced compounds isolated from plants, insects and microorganisms have been a potent source of drugs for the treatment of human diseases. In this review, we recapitulate the story of one of these compounds, 2-propylpentanoic acid, derived from the Valeriana officinalis flowering plant and its path to validation as a cancer treatment. [less ▲]

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See detailContribution of Capillary Electrophoresis and Ion Mobility Spectrometry to probe conformational change during desolvation
Far, Johann ULg; Delvaux, Cédric ULg; Kune, Christopher ULg et al

Conference (2016, January 28)

The transfer of ions from the solution to the gas phase is a critical step to produce « native species ». Coming from a highly solvating medium, ionic species will tend to find a new equilibrium ... [more ▼]

The transfer of ions from the solution to the gas phase is a critical step to produce « native species ». Coming from a highly solvating medium, ionic species will tend to find a new equilibrium conformation in the gas phase. The pathway to reach the thermodynamically stable conformation involves crossing potential barriers of different heights. When these barriers are too high compared to the internal energy of the ions, it will result in “partial memories” (as structural preservation) of the conformation in solution. In order to evaluate the effect of the solvent evaporation and of the various collision processes encountered by the ions in the mass spectrometer, we developed two strategies: The first strategy consists in comparing in a single experiment the shape of the ions in solution and in the gas phase. Data are obtained by coupling Capillary Electrophoresis (CE) with Ion Mobility Mass Spectrometry (IMS). Drift times in solution and in the gas phase are directly compared. Deviations from their correlation points out changes in folding upon desolvatation. Preliminary results show that some of peptides issued from tryptic digest of BSA clearly change their conformation during desolvatation. The second strategy consists to monitor the shape of the different conformers observed for the intact cytochrome C during native runs in capillary electrophoresis and “native” ion mobility mass spectrometry, both using a physiological TRIS acetic pH7 buffer compared to a “MS friendly” ammonium acetate pH7 buffer. Finally as preliminary study, we proposed to use homopolymers for better understanding about the folding behavior in gas phase and the resulting shape of these ions using ion mobility spectrometry. [less ▲]

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See detailDe novo sequencing using MELD proteolysis coupled to a "sequence assembly" algorithm
Mazzucchelli, Gabriel ULg; Zimmerman, Tyler A; Smargiasso, Nicolas ULg et al

Poster (2016, January 22)

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See detailEffet inflammatoire des extraits de Cupressus sempervirens planté dans l’Est de l’Algérie : du modèle murin à la stimulation des cellules BEAS-2B par l’allergène majeur Cup s 1
Bouguenoun, Imene; De Pauw-Gillet, Marie-Claire ULg; Bensakhri, Z et al

in Revue Française d'Allergologie (2016), 56

Cupressus sempervirens est l’une des espèces les plus répandues en Algérie ayant une capacité allergénique très élevée. Nous avons étudié,d’abord, comment l’instillation nasale des différentes fractions ... [more ▼]

Cupressus sempervirens est l’une des espèces les plus répandues en Algérie ayant une capacité allergénique très élevée. Nous avons étudié,d’abord, comment l’instillation nasale des différentes fractions de l’extrait pollinique de cette espèce peut moduler la réponse immunitaire chez les souris, et, ensuite, la stimulation des cellules épithéliales bronchiques humaines (BEAS-2B) par l’allergène majeur, identifié par spectrométrie de masse et purifié par chromatographie échangeuse d’ions. La sensibilisation des souris a révélé, d’une part, une diminution du nombre de neutrophiles et une augmentation des éosinophiles, et, d’autre part, une augmentation significative du total cellulaire dans le liquide du lavage bronchoalvéolaire.L’étude histologique des poumons a montré une présence d’infiltrat inflammatoire et d’oedème péri-bronchique. La spectrométrie de masse nous a permis de mettre en évidence la présence de l’allergène majeur Cup s 1 dans toutes les fractions avec une présence spécifique du Cup s 3 et Cupa 1 dans la fraction 4. Cet allergène avait le potentiel pour stimuler la libération de l’IL-8 et l’IL-6 par la ligné cellulaire, BEAS-2B, in vitro d’une manière dose-dépendante [less ▲]

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See detailAn Improved Molecular Histology Method for Ion Suppression Monitoring and Quantification of Phosphatidyl Cholines During MALDI MSI Lipidomics Analyses.
Jadoul, Laure ULg; Smargiasso, Nicolas ULg; Pamelard, Fabien et al

in OMICS : A Journal of Integrative Biology (2016), 20(2), 110-21

Tissue lipidomics is one of the latest omics approaches for biomarker discovery in pharmacology, pathology, and the life sciences at large. In this context, matrix-assisted laser desorption/ionization ... [more ▼]

Tissue lipidomics is one of the latest omics approaches for biomarker discovery in pharmacology, pathology, and the life sciences at large. In this context, matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) is the most versatile tool to map compounds within tissue sections. However, ion suppression events occurring during MALDI MSI analyses make it impossible to use this method for quantitative investigations without additional validation steps. This is especially true for lipidomics, since different lipid classes are responsible for important ion suppression events. We propose here an improved lipidomics method to assess local ion suppression of phospatidylcholines in tissues. Serial tissue sections were spiked with different amounts of PC(16:0 d31/18:1) using a nebulization device. Settings for standard nebulization were strictly controlled for a detection similar to when using spiked tissue homogenates. The sections were simultaneously analyzed by MALDI MSI using a Fourier transform ion cyclotron resonance analyzer. Such a spray-based approach allows taking into account the biochemical heterogeneity of the tissue for the detection of PC(16:0 d31/18:1). Thus, here we present the perspective to use this method for quantification purposes. The linear regression lines are considered as calibration curves and we calculate PC(16:0/18:1) quantification values for different ROIs. Although those values need to be validated by a using a different independent approach, the workflow offers an insight into new quantitative mass spectrometry imaging (q-MSI) methods. This approach of ion suppression monitoring of phosphocholines in tissues may be highly interesting for a large range of applications in MALDI MSI, particularly for pathology using translational science workflows. [less ▲]

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See detailComparison of serum fractionation methods by data independent label-free proteomics
Baiwir, Dominique ULg; Mazzucchelli, Gabriel ULg; Smargiasso, Nicolas ULg et al

in EuPA Open Proteomics (2015), 9

Off-line sample prefractionations applied prior to biomarker discovery proteomics are options to enable more protein identifications and detect low-abundance proteins. This work compared five commercial ... [more ▼]

Off-line sample prefractionations applied prior to biomarker discovery proteomics are options to enable more protein identifications and detect low-abundance proteins. This work compared five commercial methods efficiency to raw serum analysis using label-free proteomics. The variability of the protein quantities determined for each process was similar to the unprefractionated serum. A 49% increase in protein identifications and 12.2% of reliable quantification were obtained. A 61 times lower limit of protein quantitation was reached compared to protein concentrations observed in raw serum. The concentrations of detected proteins were confronted to estimated reference values. [less ▲]

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See detailGender differences in responses in Gammarus pulex exposed to BDE-47: a gel-free proteomic approach
Gismondi, Eric ULg; Mazzucchelli, Gabriel ULg; De Pauw, Edwin ULg et al

in Ecotoxicology & Environmental Safety (2015), 122

Very few ecotoxicological studies have considered differences in toxic effects on male and female organisms. Here, we investigated protein expression differences in caeca of Gammarus pulex males and ... [more ▼]

Very few ecotoxicological studies have considered differences in toxic effects on male and female organisms. Here, we investigated protein expression differences in caeca of Gammarus pulex males and females under control conditions (unexposed) and after 96 h exposure to BDE-47. Using gel-free proteomic analysis, we have identified 45 proteins, of which 25 were significantly differently expressed according to sex and/or BDE-47 exposure. These proteins were involved in several biological processes such as energy metabolism, chaperone proteins, or transcription/translation. In unexposed amphipods, 11 proteins were significantly over-expressed in females, and 6 proteins were over-expressed in males. Under BDE-47 stress, 7 proteins were differently impacted according to sex. For example, catalase was over-expressed in exposed females and under-expressed in exposed males, as compared to respective controls. Conversely, proteins involved in energy metabolism were up-regulated in males and down-regulated in females. Our proteomic study showed differences in responses of males and females to BDE-47 exposure, emphasizing that sex is a confounding factor in ecotoxicological assessment. However, due to the limited information existing in databases on Gammarids, it was difficult to define a BDE-47 mechanism of action. The gel-free proteomic seems to be a promising method to develop in future ecotoxicological studies and thus, to improve our understanding of the mechanism of action of xenobiotics. [less ▲]

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See detailImpact of Regiella insecticola infection on EBF production in Acyrthosiphon pisum Harris
Bauwens, Julien ULg; Mazzucchelli, Gabriel ULg; De Pauw, Edwin ULg et al

Conference (2015, November 06)

Symbionts of aphids influence their host from many points of view. We investigate the potential influence of bacterial symbionts on the production and emission of the aphid alarm pheromone, E-β-franesene ... [more ▼]

Symbionts of aphids influence their host from many points of view. We investigate the potential influence of bacterial symbionts on the production and emission of the aphid alarm pheromone, E-β-franesene. Some trends could be observed in the total EβF production. Particularly, aphid strains infected by Buchnera only seemed to produce less alarm pheromone. By contrast, the presence of Regiella insecticola seemed to increase EβF production. Mevalonate pathway was investigated by RT-qPCR. This analysis showed a slightly lower transcription level o mIPPS in Regiella-infected strains. This enzyme is involved in the last step of EβF production. By contrast, two enzymes involved respectively in the linkage and release of farnesyl moeities on proteins c-terminal ends. Escape tests were conducted to assay if these results were traduced by differential behavior in front of a predator. Preliminary results showed significantly higher dropping behavior for Regiella-infected strains. [less ▲]

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See detailHigh-throughput sequencing of toxins with pharmacological interest: proof of concept and first applications
Echterbille, Julien ULg; Degueldre, Michel ULg; Boulanger, Madeleine ULg et al

Conference (2015, September 28)

Animal venoms are complex chemical cocktails, comprising wide ranges of biologically active reticulated peptides that target with high selectivity and efficacy varieties of membrane receptors. Assuming ... [more ▼]

Animal venoms are complex chemical cocktails, comprising wide ranges of biologically active reticulated peptides that target with high selectivity and efficacy varieties of membrane receptors. Assuming the fact that each of the 170,000 venomous species reported can produce more than 250 bioactive toxins, at least 40,000,000 bioactive peptides and proteins may be discovered. Among the four described species of mambas, Eastern Jameson’s mamba (Dendroaspis jamesonii kaimosae) venom is the less characterized since only 9 peptides are referenced in database. This work aims at developing a new strategy devoted to the deep analysis of animal venoms. Our approach consists in a first separation of the venom using cation exchange chromatography. Each primary fraction is then purified a second time by classical RP-HPLC. A total of 328 fractions, containing amongst 1 and 4 toxins, are finally collected. MALDI-MS analysis of each fraction is done in order (1) to obtain information about masses and (2) to obtain sequences of toxins thanks to MALDI-In Source Decay (ISD) dissociation coupled with on MALDI target plate reduction of the peptides. ISD has already been demonstrated efficient for toxin sequencing1, and especially when using 1,5-DAN as reducing matrix2. ISD yields to sequences that cover more than 50% of peptide sequences by series of singly charged c-type ions. Thanks to this methodology, we were able to obtain 85% of satisfactory results i.e. spectra giving quite long tags of amino acids (up to 20 residues). As a way to validate our method, a tag coming from ISD spectrum interpretation has found a match in database for an Eastern Jameson’s mamba toxin. The global sequence has then been obtained by extrapolation on the ISD spectrum. Since ISD spectra are simpler than classical MS/MS spectra, automation of spectra interpretation, difficult with other fragmentation techniques (CID, ETD…), is implementable. In the near future, sequences obtained with this approach will be used to direct tests of biological activity through sequence homologies with already known ligands for different kinds of membrane receptors. [less ▲]

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See detailProbing the conformational changes during desolvation of ions using orthogonal mobility methods (CE-IMS)
Far, Johann ULg; Kune, Christopher ULg; Delvaux, Cédric ULg et al

Poster (2015, July 29)

The transfer of ions from the solution to the gas phase is a critical step to produce « native species ». Coming from a highly solvating medium, ionic species will tend to find a new equilibrium ... [more ▼]

The transfer of ions from the solution to the gas phase is a critical step to produce « native species ». Coming from a highly solvating medium, ionic species will tend to find a new equilibrium conformation in the gas phase. The pathway to reach the thermodynamically stable conformation involves crossing potential barriers of different heights. When these barriers are too high compared to the internal energy of the ions, it will result in “partial memories” (as structural preservation) of the conformation in solution. In order to evaluate the effect of the solvent evaporation and of the various collision processes encountered by the ions in the mass spectrometer, we developed two strategies: The first strategy consists in comparing in a single experiment the shape of the ions in solution and in the gas phase. Data are obtained by coupling capillary electrophoresis with Ion Mobility Mass Spectrometry. Drift times in solution and in the gas phase are directly compared. Deviations from their correlation points out changes in folding upon desolvatation. Preliminary results show that among peptides issued from tryptic digest of BSA some of them clearly change their conformation during desolvatation. The second strategy consists in probing changes of conformation once the ions are in the gas phase. The ions are rapidly heating by collisions ions during their transfer to the IMS. The heating is obtained by increasing their collision energy, rapidly followed by thermalisation in the IMS cell. The ions may be kinetically trapped in their new conformations. This allows comparing barriers between different ions geometries. In summary this work intends to evaluate the extent of conformational “memory” of the ions of different nature for best experimental condition allowing “native mass spectrometry” [less ▲]

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See detailCONTRIBUTION OF ION MOBILITY FOR STRUCTURAL ANALYSIS AND ANALYTICAL CHEMISTRY: THE USE OF PROBE LIGANDS AND SELECTIVE IMS SHIFT REAGENTS
Kune, Christopher ULg; Far, Johann ULg; Delvaux, Cédric ULg et al

Conference (2015, July 28)

Ion mobility is a gas phase separation technique sensitive to the Collisional Cross Section (CCS) difference of ions (as CCS/ΔCCS). It discriminates isobaric and isomeric ions when CCS difference is ... [more ▼]

Ion mobility is a gas phase separation technique sensitive to the Collisional Cross Section (CCS) difference of ions (as CCS/ΔCCS). It discriminates isobaric and isomeric ions when CCS difference is larger than the instrumental resolution (roughly 50). To overcome the usual resolution of ion mobility (IM), it is necessary to use new strategies in addition to the optimization of the ion mobility parameters. This work proposes a new method to bypass this limitation while providing additional structural information by the use of Selective Shift Reagents (SSR). A SSR can specifically bind with a target ion depending of their physicochemical properties like chemical groups, steric hindrance, polarity, space charge effects… In this strategy, the choice of SSR is fundamental. SSR could be empirically selected or assisted and designed by computational chemistry prediction. SSR can be used as a chemical probe which can support physicochemical properties and help or confirm hypotheses for structural elucidation. They can also drastically change the CCS of a target ion present in a complex mixture (e.g. biological origin sample) as shifting reagent for e.g. quantification purpose. Models used for the proof of concept have been selected in order to lead to an expected or predictive result. Firstly crown ethers have been used as SSR in IMS to shift the protonated valine drift time from the protonated proline drift time according to their chemical groups and especially amino groups. The selectivity of SSR leads to an improved separation between valine and proline. Secondly three structural isomers of diaminonaphthalene were investigated experimentally and theoretically using computational chemistry support after the addition of different crown ethers or β-cyclodextrin as SSR to improve the separation of these isomers by IMS. Finally, the concept of SSR was successfully applied to biological origin samples to elucidate structure and allows the quantification of selenium (Se) containing compounds present in an aqueous extract of Se rich yeast. [less ▲]

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See detailTravelling-wave ion mobility time-of-flight mass spectrometry as an alternative strategy for screening of multi-class pesticides in fruits and vegetables
Goscinny, Séverine ULg; Joly, Laure; De Pauw, Edwin ULg et al

in Journal of Chromatography. A (2015), 1405

This paper reports a novel approach to screening multi-class pesticides by ion mobility timeof- flight mass spectrometry detection. Nitrogen was selected as mobility gas. After optimization of the ... [more ▼]

This paper reports a novel approach to screening multi-class pesticides by ion mobility timeof- flight mass spectrometry detection. Nitrogen was selected as mobility gas. After optimization of the different ion mobility parameters, determination of matrix effect on the drift times was conducted using different matrix extracts. The results showed that drift time values are not influenced by the matrix and also are independent of the concentration within the working range for 100 pesticides tested, making drift time a powerful additional identification tool. Based on statistics, 2% variation criteria provides a good fit for all the pesticides targeted, and could be considered as a maximum acceptable criteria associated with the drift time parameter for identification purpose. This 2% value is in agreement with already reported criteria, for instance, for GC or LC retention time in European documents. Finally, the well-known feature of mobility to separate complex mixtures was also tested to obtain purified extracted mass spectra of pesticides in fruit extract. [less ▲]

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See detailEnergetics and Structural Characterization of Isomers Using Ion Mobility and Gas-phase H/D Exchange: Learning from Lasso Peptides
Hanozin, Emeline ULg; Morsa, Denis ULg; De Pauw, Edwin ULg

in Proteomics (2015), early view

State-of-the-art characterization of proteins using mass spectrometry namely relies on fragmentation methods which allows exploring featured dissociative reaction pathways. These pathways are often ... [more ▼]

State-of-the-art characterization of proteins using mass spectrometry namely relies on fragmentation methods which allows exploring featured dissociative reaction pathways. These pathways are often initiated by a series of potentially informative mass-constant conformational changes that are nonetheless frequently overlooked by lack of adequate investigation techniques. In the present study, we propose a methodology to readily address both structural and energetic aspects of stereoisomerization reactions using ion mobility coupled with mass spectrometry. To this end, a commercial spectrometer was used as a reactor comprising an energy resolved collisional activation step intended at promoting controlled conformational changes and a structural assignment step dedicated to the identification of the generated isomers. This identification relies on ion mobility and other on-line coupled techniques, namely an originally designed gas-phase H/D exchange experiment. We here apply this methodology to characterize the isomerization kinetics of capistruin, a 19-residue long lasso-folded peptide. We expect this approach to bring insights into the physical origin of global dissociation thresholds monitored in tandem mass spectrometry experiments and to set a promising basis for quantitative investigations of the stability of different molecular folds. [less ▲]

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