Publications

Année Type Filtrer >


1
SANTARELLI, Xavier;
Binding and Elution Properties of Mixed-Mode Chromatography and Its Applications for Purification
Current protein & peptide science, 2019, 20, 3-3
2 […]
SANTARELLI, Xavier; CABANNE, Charlotte;
Mixed Mode Chromatography: A Novel Way Toward New Selectivity
Current protein & peptide science, 2019, 20, 14-21
Mixed mode chromatography offers a diversity of ligands, each providing a new selectivity. This allows the design of novel purification processes with reduced column steps. Structure of ligands is based on both hydrophobic and ionic groups. Thanks to its salt tolerance, crude extracts or post-IEX samples can be loaded directly without conditioning. The selectivity could be enhanced by modulating elution parameters or by using additives. More importantly, mixed mode chromatography could be as effective as affinity chromatography for mAb purification processes. Mixed mode chromatography opens the way to short and economical processes.
3 […]
CABANNE, Charlotte; SANTARELLI, Xavier;
Mixed Mode Chromatography, Complex Development for Large Opportunities
Current protein & peptide science, 2019, 20, 22-27
Mixed mode chromatography resins with salt tolerance, large design space and orthogonal selectivity requires a slightly more complex development than traditional resins. It is important to screen several ligands and several binding and elution conditions. This allows taking full advantage of these resins. High-Throughput Screening (HTS) for Process Development should be done with the help of Design of Experiment (DoE). It could be performed in filter plates or Robocolumns, and assisted by liquid handling automated workstation. Modeling of the results allows the choice of optimal parameters that can then be validated and scaled up. All this leads to a better knowledge and robustness of the purification step.
4 […]
OUK, Tan Sothea;
Synthesis, characterization, and antibacterial activities of a new lignocellulosic material carrying aryl triazole moiety
Polymers for Advanced Technologies, 2019, 30, 344-350
Contamination of surfaces by bacteria and the emergence of antimicrobial resistant strains are very worrying issues. One of ways to limit the bacterial proliferation is to develop antimicrobial materials. We reported herein the development of new antimicrobial support by grafting different aryl azide onto propargylated Kraft Pulp, using the copper (I)-catalyzed alkyne-azide 1,3-dipolar cycloaddition (CuAAC) reaction, forming 1,2,3-triazole aryl. These novel materials have been investigated for their antibacterial properties against Escherichia coli and Staphylococcus aureus. The developed materials acquire its antimicrobial potential only after grafting via triazole link. Depending on the substituent of the grafted aryl, the elaborated materials showed a bacteriostatic or even bactericidal activity.
5 […]
BRESSOLLIER, Philippe;
Identification and role of Opuntia ficus indica constituents in the flocculation mechanism of colloidal solutions
Separation and Purification Technology, 2019, 209, 892-899
Opuntia ficus indica has been identified for its bioflocculant properties in water treatment; however, its underlying mechanism and active compounds have not been clearly identified. Flocculent molecules of cactus solid material (CSM) under alkaline conditions were extracted at pH 10 and then precipitated under neutral conditions (pH 7). The precipitate was fractionated by ultrafiltration systems and analyzed using inverted phase chromatography and enzymatic treatments. This approach revealed that quercetin and starch constitute the active agents found in the fractionated parts at <= 3,000 and >= 10,000 Da, respectively. The use of quercetin or (potato) starch alone at 18 mg/L yielded 72% +/- 2% and 54% +/- 3% of turbidity removal, respectively. With a combination of both these components, a higher flocculation activity (84% +/- 2%) could be obtained. From these experimental results, a flocculation model based on identified active constituents is being proposed in order to improve process knowledge.
6 […]
SIMON, Anne; FAURE, Chrystel;
Cu2+-loaded cellulose micro-beads applied to the direct patterning of metallic surfaces using a fast and convenient process
Carbohydrate Polymers, 2019, 207, 492-501
In this paper, we propose both a new application for cellulose micro-beads and a new concept in colloidal lithography to directly deposit and template a metal from ions transported by the organized colloidal particles, using the colloidal particles themselves. To do so, 5 mu m-sized cellulose micro-beads (C mu Bs) were first surface-functionalized by trimellitic anhydride to introduce carboxylate ligands before decorating them with Cu2+ ions by complexation of the carboxylate groups with a CuCl2 solution. The Cu2+-loaded C mu Bs, dispersed in an aqueous phase, were organized in compact monolayer at the vicinity of a planar electrode. The release of cupric ions and subsequent copper deposition were triggered by an electric field delivered by a tension generator. 2D non-close-packing arrays of copper dots assemblies displaying hexagonal symmetry were generated below or around the micro-beads - depending on the ions concentration in the aqueous phase - leading respectively to copper dots deposited circularly or concentrated in rings. The Cu2+-loaded cellulose beads allowed the covering of 2 cm(2)-surfaces by copper patterns in less than 45 min, using an easy and cheap process.
7 […]
JOSEPH, Cécile; SAVOIRE, Raphaelle; MONTEIL, Julien; LEAL-CALDERON, Fernando; FAURE, Chrystel;
O/W Pickering emulsions stabilized by cocoa powder: Role of the emulsification process and of composition parameters
Food research international (Ottawa, Ont.), 2019, 116, 755-766
We fabricated oil-in-water emulsions stabilized by delipidated commercial cocoa powder. The emulsions were characterized in terms of droplets and particles size distribution and interfacial coverage by cocoa powder by developing methods to separate droplets from adsorbed and unadsorbed cocoa particles. Three different processes were compared for their ability to produce fine and stable emulsions: rotor/stator turbulent mixing, sonication and microfluidization. Among those techniques, microfluidization was the most performing one. In this case, micron-sized emulsions with narrow size distributions could be obtained with >90 wt% of the powder insoluble material anchored to the interfaces, and they were still stable after 90 days. It was demonstrated that the mixing process did not generate finer cocoa particles but provoked disentanglement of the large primary particles, providing them an open, expanded structure that facilitated emulsification. It was also shown that the finer insoluble fraction of the powder and the soluble fraction had no significant impact on emulsification and on kinetic stability. In the poor particles regime, the oil-water interfacial area varied linearly with the amount of adsorbed powder, suggesting that the final droplet size was controlled by the so-called limited coalescence process, as already observed in conventional Pickering emulsions stabilized by spherical solid particles.
8 […]
HARTE, Etienne; ALVES, Isabel; ELEZGARAY, Juan;
Thickness determination in anisotropic media with plasmon waveguide resonance imaging
Opt Express, 2019, 27, 3264-3275
This paper describes a simple procedure to determine the local thickness of a thin anisotropic layer. It also discriminates between isotropic and anisotropic regions, provided a smoothness hypothesis on the refractive index distribution is satisfied. The procedure is based on the analysis of surface plasmon resonance (SPR) data acquired in an imaging mode. The general arrangement of the setup is the Kretschmann configuration. We show, on an azobenzene modified polymer layer, good agreement between atomic force microscopy and optical measurements of thickness variation.
9 […]
SALVADOR, Dimitri; GLAVIER, Marie; TAVEAU, Jean-Christophe; LECOMTE, Sophie; LAMBERT, Olivier;
Minimal nanodisc without exogenous lipids for stabilizing membrane proteins in detergent-free buffer
Biochimica et biophysica acta. Biomembranes, 2019, 1861, 852-860
Membrane protein stabilization after detergent solubilization presents drawbacks for structural and biophysical studies, in particular that of a reduced stability in detergent micelles. Therefore, alternative methods are required for efficient stabilization. Lipid nanodisc made with the membrane scaffold protein MSP is a valuable system but requires a fine optimization of the lipid to protein ratio. We present here the use of the scaffold protein MSP without added lipids as a minimal system to stabilize membrane proteins. We show that this method is applicable to alpha-helical and beta-strands transmembrane proteins. This method allowed cryo-electron microscopy structural study of the bacterial transporter MexB. A protein quantification indicates that MexB is stabilized by two MSP proteins. This simplified and efficient method proposes a new advance in harnessing the MSP potential to stabilize membrane proteins.
10 […]
BONNEU, Marc;
Metabolomics and proteomics identify the toxic form and the associated cellular binding targets of the anti-proliferative drug AICAR
The Journal of biological chemistry, 2019, 294, 805-815
5-Aminoimidazole-4-carboxamide 1-beta-d-ribofuranoside (AICAR, or acadesine) is a precursor of the monophosphate derivative 5-amino-4-imidazole carboxamide ribonucleoside 5'-phosphate (ZMP), an intermediate in de novo purine biosynthesis. AICAR proved to have promising anti-proliferative properties, although the molecular basis of its toxicity is poorly understood. To exert cytotoxicity, AICAR needs to be metabolized, but the AICAR-derived toxic metabolite was not identified. Here, we show that ZMP is the major toxic derivative of AICAR in yeast and establish that its metabolization to succinyl-ZMP, ZDP, or ZTP (di- and triphosphate derivatives of AICAR) strongly reduced its toxicity. Affinity chromatography identified 74 ZMP-binding proteins, including 41 that were found neither as AMP nor as AICAR or succinyl-ZMP binders. Overexpression of karyopherin-beta Kap123, one of the ZMP-specific binders, partially rescued AICAR toxicity. Quantitative proteomic analyses revealed 57 proteins significantly less abundant on nuclei-enriched fractions from AICAR-fed cells, this effect being compensated by overexpression of KAP123 for 15 of them. These results reveal nuclear protein trafficking as a function affected by AICAR.
11 […]
VALLADE, Maëlle; JEWGINSKI, Michal; BURATTO, Jérémie; BATHANY, Katell; SCHMITTER, Jean-Marie; STUPFEL, Marine; GODDE, Frédéric; HUC, Ivan;
Assessing Interactions between Helical Aromatic Oligoamide Foldamers and Protein Surfaces: A Tethering Approach
Bioconjugate Chemistry, 2019, 30, 54-62
Helically folded aromatic foldamers may constitute suitable candidates for the ab initio design of ligands for protein surfaces. As preliminary steps toward the exploration of this hypothesis, a tethering approach was developed to detect interactions between a protein and a foldamer by confining the former at the surface of the latter. Cysteine mutants of two therapeutically relevant enzymes, CypA and IL4, were produced. Two series of ten foldamers were synthesized bearing different proteinogenic side chains and either a long or a short linker functionalized with an activated disulfide. Disulfide exchange between the mutated cysteines and the activated disulfides yielded 20 foldamer-IL4 and 20 foldamer-CypA adducts. Effectiveness of the reaction was demonstrated by LC-MS, by MS analysis after proteolytic digestion, and by 2D NMR. Circular dichroism then revealed diastereoselective interactions between the proteins and the foldamers confined at their surface which resulted in a preferred handedness of the foldamer helix. Helix sense bias occurred sometimes with both the short and the long linkers and sometimes with only one of them. In a few cases, helix handedness preference is found to be close to quantitative. These cases constitute valid candidates for structural elucidation of the interactions involved.
12 […]
HASTOY, Benoit; SCOTTI, Pier; MILOCHAU, Alexandra; BATHANY, Katell; DESBAT, Bernard; CASTANO, Sabine; ODA, Reiko; LANG, Jochen;
The transmembrane domain of the SNARE protein VAMP2 is highly sensitive to its lipid environment
Biochimica et biophysica acta. Biomembranes, 2019, 1861, 670-676
Neurotransmitter and hormone exocytosis depends on SNARE protein transmembrane domains and membrane lipids but their interplay is poorly understood. We investigated the interaction of the structure of VAMP2, a vesicular transmembrane SNARE protein, and membrane lipid composition by infrared spectroscopy using either the wild-type transmembrane domain (TMD), VAMP2TM22, or a peptide mutated at the central residues G100/C103 (VAMP2TM22VV) previously identified by us as being critical for exocytosis. Our data show that the structure of VAMP2TM22, in terms of alpha-helices and beta-sheets is strongly influenced by peptide/lipid ratios, by lipid species including cholesterol and by membrane surface charges. Differences observed in acyl chain alignments further underscore the role of the two central small amino acid residues G100/C103 within the transmembrane domain during lipid rearrangements in membrane fusion. Copyright © 2018 Elsevier B.V. All rights reserved.
13 […]
MARTINEZ, Denis; LOQUET, Antoine; HABENSTEIN, Birgit;
Avidity-driven polarity establishment via multivalent lipid-GTPase module interactions
The EMBO journal, 2019, 38,
While Rho GTPases are indispensible regulators of cellular polarity, the mechanisms underlying their anisotropic activation at membranes have been elusive. Using the budding yeast Cdc42 GTPase module, which includes a guanine nucleotide exchange factor (GEF) Cdc24 and the scaffold Bem1, we find that avidity generated via multivalent anionic lipid interactions is a critical mechanistic constituent of polarity establishment. We identify basic cluster (BC) motifs in Bem1 that drive the interaction of the scaffold-GEF complex with anionic lipids at the cell pole. This interaction appears to influence lipid acyl chain ordering, thus regulating membrane rigidity and feedback between Cdc42 and the membrane environment. Sequential mutation of the Bem1 BC motifs, PX domain, and the PH domain of Cdc24 lead to a progressive loss of cellular polarity stemming from defective Cdc42 nanoclustering on the plasma membrane and perturbed signaling. Our work demonstrates the importance of avidity via multivalent anionic lipid interactions in the spatial control of GTPase activation.
14 […]
MARTINEZ, Denis; HABENSTEIN, Birgit; LOQUET, Antoine;
Molecular mechanisms for the destabilization of model membranes by islet amyloid polypeptide
Biophysical chemistry, 2019, 245, 34-40
Misfolding of human islet amyloid polypeptide (hIAPP) into insoluble aggregates is associated with Type 2 diabetes. It has been suggested that hIAPP toxicity may be due to its accumulation in pancreatic islets, causing membrane disruption and cell permeabilization, however the molecular basis underlying its lipid association are still unclear. Here, we combine solid-state NMR, fluorescence and bright field microscopy to investigate hIAPP - lipid membrane interactions. Real-time microscopy highlights a time-dependent penetration of hIAPP oligomers toward the most buried layers of the lipid vesicles until the membrane disrupts. Deuterium NMR was conducted on liposomes at different hIAPP concentration to probe lipid internal order and thermotropism. The gel-to-fluid phase transition of the lipids is decreased by the presence of hIAPP, and site-specific analysis of the order parameter showed a significant increase of lipid order for the first eight positions of the acyl chain, suggesting a partial insertion of the peptide inside the bilayer. These results offer experimental insight into the membrane destabilization of hIAPP on model membrane vesicles.
15 […]
GRELARD, Axelle; DUFOURC, Erick;
Heat-Triggered Crystallization of Liquid Crystalline Macrocycles Allowing for Conductance Switching through Hysteretic Thermal Phase Transitions
Chemistry-an Asian Journal, 2019, 14, 141-148
A polymesomorphic thermal phase-transition of a macrocyclic amphiphile consisting of aromatic groups and oligoethylene glycol (OEG) chains is reported. The macrocyclic amphiphile exists in a highly-ordered liquid crystal (LC) phase at room temperature. Upon heating, this macrocycle shows phase-transition from columnar-lamellar to nematic LC phases followed by crystallization before melting. Spectroscopic studies suggest that the thermally induced crystallization is triggered by a conformational change at the OEG chains. Interestingly, while the macrocycle returns to the columnar-lamellar phase after cooling from the isotropic liquid, it retains the crystallinity after cooling from the thermally-induced crystal. Thanks to this bistability, conductance switching was successfully demonstrated. A different macrocyclic amphiphile also shows an analogous phase-transition behavior, suggesting that this molecular design is universal for developing switchable and memorizable materials, by means of hysteretic phase-transition processes.
16 […]
MOLINARI, Michael;
Real Time and Quantitative Imaging of Lignocellulosic Films Hydrolysis by Atomic Force Microscopy Reveals Lignin Recalcitrance at Nanoscale
Biomacromolecules, 2019, 20, 515-527
Lignocellulosic biomass is considered as a sustainable source of energy and chemicals, but its recalcitrance to bioconversion still limits its use. In this paper, a strategy based on two aspects was developed to improve our knowledge on the lignin recalcitrance to enzymatic hydrolysis. First, lignocellulosic films of cellulose nanofibrils (CNFs) with increasing content of lignin (up to 40%) were prepared. Thanks to in situ real time Atomic Force Microscopy (AFM) measurements during the hydrolysis and by comparison with biochemical assays, the use of such films allows to fully assess the importance of the lignin content and of the arrangement between CNFs and lignin on the hydrolysis efficiency. In a second time, contrary to other studies by AFM which only followed a specific structure during enzymatic processes mostly on simple systems (CNFs or cellulose nanocrystals), a quantitative analysis of in-situ time-lapse measurements was developed. It enables to accurately address lignocellulosic biomass recalcitrance mechanisms mediated by lignin at nanoscale. Such analysis could pave the way for the use of a quantitative criteria to visualize in situ deconstruction of complex lignocellulosic substrates. Coupling the use of lignocellulosic films and dynamical AFM quantitative analysis to follow the evolution of the structure at nanoscale might lead to an effective targeting of new promising bioconversion strategies.
17 […]
URDACI, Maria;
(EN) Probiotic Strains for Treating and/or Preventing Diarrhea
, 2019, 0,
The present invention relates to a method of selecting or identifying probiotic strains capable of acting on the absorption of water in the colon, and use thereof as medicinal products in the treatment and/or prevention of diarrhea. The invention relates in particular to the strain of Bacillus subtilis CU1 for use in the treatment and/or prevention of diarrhea.
18 […]
BRESSOLLIER, Philippe;
(EN) PSEUDOTSUGA MENZIESII EXTRACT, METHOD FOR OBTAINING SAME AND USE THEREOF (FR) EXTRAIT DE PSEUDOTSUGA MENZIESII, PROCEDE D'OBTENTION ET UTILISATIONS
, 2019, 0,
(EN) The invention concerns a method for simultaneously extracting at least one lipophilic molecule and at least one polyphenolic compound from Pseudotsuga menziesii, comprising at least one step of extraction by percolation diffusion of a pressurised solvent in a fixed bed reactor carried out from a raw material derived from Pseudotsuga menziesii. The invention also concerns the concentrate obtained during the implementation of the method, and the extracts obtained and the uses of same. (FR) L'objet de l'invention est un procédé d'extraction simultanée d'au moins une molécule lipophile et d'au moins un composé polyphénolique de Pseudotsuga menziesii, comprenant au moins une étape d'extraction par percolation diffusion d'un solvant sous pression en réacteur à lit fixe réalisée à partir d'une matière première dérivée de Pseudotsuga menziesii. L'invention vise aussi le concentrât obtenu pendant la mise en œuvre du procédé, ainsi que les extraits obtenus et leurs utilisations.
19 […]
FAURE, Chrystel; JOSEPH, Cécile; LEAL-CALDERON, Fernando; CANSELL, Maud;
EN) METHOD FOR PRODUCING PICKERING EMULSIONS FROM BIOSOURCED PARTICLES (FR) PROCÉDÉ DE PRÉPARATION D'ÉMULSIONS DE PICKERING À PARTIR DE PARTICULES BIOSOURCÉES
, 2019, 0,
(EN) The present invention relates to a method for producing a Pickering emulsion, comprising the steps of: a) producing a plant powder of at least one oleaginous species; b) adding said plant powder, either to an aqueous phase to obtain a suspension (S) or to an oil phase to obtain a suspension (S'), followed by incorporating either oil into suspension (S) to obtain an oil-in-water type emulsion, or water into suspension (S') to obtain a water-in-oil type emulsion; and c) stirring the emulsion that was obtained at the end of the previous step. (FR) La présente invention concerne un procédé de préparation d'une émulsion de Pickering comprenant les étapes suivantes : a) la préparation d'une poudre végétale d'au moins une espèce oléagineuse; b) l'addition de ladite poudre végétale - soit dans une phase aqueuse pour obtenir une suspension (S), - soit dans une phase huileuse pour obtenir une suspension (S'), suivie de l'incorporation - soit d'huile dans la suspension (S) pour obtenir une émulsion de type huile- dans-eau, - soit d'eau dans la suspension (S') pour obtenir une émulsion de type eau- dans-huile; et c) l'agitation de l'émulsion obtenue à l'issue de l'étape précédente.
20 […]
FAURE, Chrystel; JOSEPH, Cécile; LEAL-CALDERON, Fernando; CANSELL, Maud;
(EN) METHOD FOR PRODUCING DRY EMULSIONS FROM BIOSOURCED PARTICLES (FR) PROCÉDÉ DE PRÉPARATION D'ÉMULSIONS SÈCHES À PARTIR DE PARTICULES BIOSOURCÉES
, 2019, 0,
(EN) The present invention relates to a method of producing a dry emulsion, involving a step of drying an oil-in-water Pickering emulsion that contains particles of plant powder. The invention also relates to the dry emulsions which can be obtained by following said method. (FR) La présente invention concerne un procédé de préparation d'une émulsion sèche, comprenant une étape de séchage d'une émulsion de Pickering huile-dans- eau contenant des particules de poudre végétale. Elle concerne également les émulsions sèches susceptibles d'être obtenues selon ledit procédé.
21 […]
GUICHARD, Gilles; FREMAUX, Juliette; VENIN, Claire;
PRO-DRUG PEPTIDE WITH IMPROVED PHARMACEUTICAL PROPERTIES
, 2019, 0,
The present disclosure relates to a pro-drug peptide, or a salt thereof, having improvement for at least one biological property relative to a parent peptide or peptidomimetic, wherein the biological property is selected from the group consisting of therapeutic index, stability, solubility, toxicity, adsorption, and pre-systemic metabolism. The pro-drug peptide comprising the following structure: Z-pep, wherein: pep is the parent peptide or peptidomimetic; Z is a sequence of n amino acids, Z is cleaved in vivo releasing pep; n≥2 amino acids. The present disclosure also relates to methods of making and using the pro-drug peptide of the present disclosure. For example, the present disclosure describes a pro-drug peptide that may be used to prevent, treat, or ameliorate at least one symptom of hypoglycemia or a hypoglycemia-related disease or disorder.
22 […]
PEDROSA, Catarina; KHAN, Irfan; DURRIEU, Marie-Christine;
Controlled Nanoscale Topographies for Osteogenic Differentiation of Mesenchymal Stem Cells
Acs Applied Materials & Interfaces, 2019, 11, 8858-8866
Nanotopography with length scales of the order of extracellular matrix elements offers the possibility of regulating cell behavior. Investigation of the impact of nanotopography on cell response has been limited by the inability to precisely control geometries, especially at high spatial resolutions and across practically large areas. In this paper, we demonstrate well-controlled and periodic nanopillar arrays of silicon and investigate their impact on osteogenic differentiation of human mesenchymal stem cells (hMSCs). Silicon nanopillar arrays with critical dimensions in the range of 40-200 nm, exhibiting standard deviations below 15% across full wafers, were realized using the self-assembly of block copolymer colloids. Immunofluorescence and quantitative polymerase chain reaction measurements reveal clear dependence of osteogenic differentiation of hMSCs on the diameter and periodicity of the arrays. Further, the differentiation of hMSCs was found to be dependent on the age of the donor. While osteoblastic differentiation was found to be promoted by the pillars with larger diameters and heights independent of donor age, they were found to be different for different spacings. Pillar arrays with smaller pitch promoted differentiation from a young donor, while a larger spacing promoted those of an old donor. These findings can contribute for the development of personalized treatments of bone diseases, namely, novel implant nanostructuring depending on patient age.
23 […]
GERBOD-GIANNONE, Marie-Christine; DALLET, Laurence; NAUDIN, Grégoire; SAHIN, Annelise; POUSSARD, Sylvie; LAMBERT, Olivier;
Involvement of caveolin-1 and CD36 in native LDL endocytosis by endothelial cells
Biochimica et biophysica acta. General subjects, 2019, 1863, 830-838
Atherosclerosis is a lipid disease characterized by accumulation of low density lipoprotein (LDL) in the artery wall. The transport of LDL across the endothelium of coronary artery is an initiating event of atherosclerosis, whose mechanism remains poorly understood. In the last decade, it has been shown that in caveolin-1 (Cav-1) deficient mice, LDL infiltration in aorta wall is decreased and CD36 expression in aortas is down-regulated, leading to regression of atherosclerotic lesions. In the present study, we show that native LDL endocytosis is decreased in endothelial cells deficient in Cav-1 or CD36. We demonstrate that Cav-1 and CD36 interact in caveolae-rich domains by different biochemical approaches. In addition, confocal microscopy reveals some colocalization of Cav-1 with CD36. These findings indicate that caveolae and CD36 are involved in native LDL endocytosis and suggest that CD36 might be a good candidate for the transport of native LDL across the endothelium, an early event in atherosclerosis.
24 […]
WANG, Xiang; GAN, Quan; WICHER, Barbara; FERRAND, Yann; HUC, Ivan;
Directional Threading and Sliding of a Dissymmetrical Foldamer Helix on Dissymmetrical Axles
Angewandte Chemie (International ed. in English), 2019, 58, 4205-4209
We have investigated the self-assembly of a dissymmetrical aromatic oligoamide helix on linear amido-carbamate rods. A dissymmetric sequence bearing two differentiated ends is able to wrap around dissymmetric dumbbell guest molecules. Structural and thermodynamic investigations allowed us to decipher the mode of binding of the helix that can bind specifically to the amide and carbamate groups of the rod. In parallel kinetic studies of threading and sliding of the helix along linear axles were also monitored by 1 H NMR. Results show that threading of a dissymmetrical host can be kinetically biased by the nature of the guest terminus allowing a preferential sense of sliding of the helix. The study presented below further demonstrates the valuable potential of foldaxanes to combine designed molecular recognition patterns with fine control of self-assembly kinetics to conceive complex supramolecular events. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
25 […]
LOMBARDO, Caterina Maria; DOUAT, Céline; GUICHARD, Gilles;
Design and Structure Determination of a Composite Zinc Finger Containing a Nonpeptide Foldamer Helical Domain
Journal of the American Chemical Society, 2019, 141, 2516-2525
A number of foldamer backbones have been described as useful mimics of protein secondary structure elements, enabling for example the design of synthetic oligomers with the ability to engage specific protein surfaces. Synthetic folded backbones can also be used to create artificial proteins in which a folded peptide segment (e.g., an alpha-helix, a loop) is replaced by its unnatural counterpart, with the expectation that the resulting molecule would maintain its ability to fold while manifesting new exploitable features. The similarities in screw sense, pitch, and polarity between peptide alpha-helices and oligourea 2.5-helices suggest that a tertiary structure could be retained when swapping the two backbones in a protein sequence. In the present work, we move a step toward the creation of such composite proteins by replacing the 10-residue long original alpha-helical segment in the Cys2His2 zinc finger 3 of transcription factor Egrl (also known as Zif268) by an oligourea sequence bearing two appropriately spaced imidazole side chains for zinc coordination. We show by spectroscopic techniques and mass spectrometry analysis under native conditions that the ability of the peptide/oligourea hybrid to coordinate the zinc ion is not affected by the foldamer replacement. Moreover, detailed NMR analysis provides evidence that the engineered zinc finger motif adopts a folded structure in which the native beta-sheet arrangement of the peptide region and global arrangement of DNA-binding side chains are preserved. Titration in the presence of the Egrl target DNA sequence supports binding to GC bases as reported for the wild type zinc finger.
26 […]
FREMAUX, Juliette; VENIN, Claire; MAURAN, Laura; GUICHARD, Gilles;
Peptide-oligourea hybrids analogue of GLP-1 with improved action in vivo
Nature Communications, 2019, 10,
Peptides have gained so much attention in the last decade that they are now part of the main strategies, with small molecules and biologics, for developing new medicines. Despite substantial progress, the successful development of peptides as drugs still requires a number of limitations to be addressed, including short in vivo half-lives and poor membrane permeability. Here, we describe the use of oligourea foldamers as tool to improve the pharmaceutical properties of GLP-1, a 31 amino acid peptide hormone involved in metabolism and glycemic control. Our strategy consists in replacing four consecutive amino acids of GLP-1 by three consecutive ureido residues by capitalizing on the structural resemblance of oligourea and alpha-peptide helices. The efficacy of the approach is demonstrated with three GLP-1-oligourea hybrids showing prolonged activity in vivo. Our findings should enable the use of oligoureas in other peptides to improve their pharmaceutical properties and may provide new therapeutic applications.
27 […]
JOBIN, Marie-Lise; ALVES, Isabel;
The Contribution of Differential Scanning Calorimetry for the Study of Peptide/Lipid Interactions
Methods Mol Biol, 2019, 1964, 3-15
Membrane-active peptides include a variety of molecules such as antimicrobial (AMP), cell-penetrating (CPP), viral, and amyloid peptides that are implicated in several pathologies. They constitute important targets because they are either at the basis of novel therapies (drug delivery for CPPs or antimicrobial activity for AMPs) or they are the agents causing these pathologies (viral and amyloid peptides). They all share the common property of interacting with the cellular lipid membrane in their mode of action. Therefore, a better understanding of the peptide/lipid (P/L) interaction is essential to help decipher their mechanism of action. Among the different biophysical methods that can be used to fully characterize P/L interactions, differential scanning calorimetry (DSC) allows determining the peptide effect on the lipid phase transitions, a property that reflects the P/L interaction mode. A general protocol for classical DSC experiments for P/L studies will be provided.
28 […]
POUGET, Emilie; SCALABRE, Antoine;
Adsorption of Proteins on Dual Loaded Silica Nanocapsules
Journal of Physical Chemistry B, 2019, 123, 1708-1717
The design of nanocarriers containing hydrophobic and hydrophilic compounds represents a powerful tool for cocktail delivery. Water-in-oil-in-water emulsions constitute an attractive approach, as they offer dual encapsulation and provide a template for the constitution of a capsule. A limitation in the preparation of nano double emulsions is their instability resulting from high curvature radii. In this work, silica nanocapsules (NCs) stable over several months were synthesized. This was achieved by exploiting a double emulsion in which the oil phase is constituted by a combination of oils presenting several volatilities. The decrease of oil droplet size by evaporation favored the deposition of a silica layer at the nanoscale interface. The release of the payload obtained by drying the capsules was investigated by fluorescence spectroscopy. Understanding the interactions between proteins and nanocapsules is a fundamental point for many biological applications. Nanocapsules were exposed to two model proteins, which were bovine serum albumin (BSA) and lysozyme (Ly). These proteins, presenting differences in charges and size, showed distinctive arrangements onto the nanocapsules. Moreover, we have studied changes in alpha-helix and beta-sheet content, which divulged the interactions between the proteins and the nanocapsules.
29 […]
HARTE, Etienne; ALVES, Isabel; ABDULHALIM, Ibrahim;
Improved Detection of Plasmon Waveguide Resonance Using Diverging Beam, Liquid Crystal Retarder, and Application to Lipid Orientation Determination
Sensors (Basel, Switzerland), 2019, 19,
Plasmon waveguide resonance (PWR) sensors exhibit narrow resonances at the two orthogonal polarizations, transverse electric (TE) and transverse magnetic (TM), which are narrower by almost an order of a magnitude than the standard surface plasmon resonance (SPR), and thus the figure of merit is enhanced. This fact is useful for measuring optical anisotropy of materials on the surface and determining the orientation of molecules with high resolution. Using the diverging beam approach and a liquid crystal retarder, we present experimental results by simultaneous detection of TE and TM polarized resonances as well as using fast higher contrast serial detection with a variable liquid crystal retarder. While simultaneous detection makes the system simpler, a serial one has the advantage of obtaining a larger contrast of the resonances and thus an improved signal-to-noise ratio. Although the sensitivity of the PWR resonances is smaller than the standard SPR, the angular width is much smaller, and thus the figure of merit is improved. When the measurement methodology has a high enough angular resolution, as is the one presented here, the PWR becomes advantageous over other SPR modes. The possibility of carrying out exact numerical simulations for anisotropic molecules using the 4 * 4 matrix approach brings another advantage of the PWR over SPR on the possibility of extracting the orientation of molecules adsorbed to the surface. High sensitivity of the TE and TM signals to the anisotropic molecules orientation is found here, and comparison to the experimental data allowed detection of the orientation of lipids on the sensor surface. The molecular orientations cannot be fully determined from the TM polarization alone as in standard SPR, which underlines the additional advantage of the PWR technique.
Groupe de Bernard Gallois Accueil Members Publications
informations Dernière mise à jour : 20/03/2014


Le CNRS Université de Bordeaux Institut Polytechnique de Bordeaux