References of "Chamot-Rooke, Julia"
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See detailIdentification and functional characterization of a novel αlpha-conotoxin (EIIA) from Conus ermineus
Quinton, Loïc ULg; Servent, Denis; Girard, Emmanuelle et al

in Analytical and Bioanalytical Chemistry (2013), 405

Nicotinic acetylcholine receptors (nAChRs) are one of the most important families in the ligand-gated ion channel superfamily due to their involvement in primordial brain functions and in several ... [more ▼]

Nicotinic acetylcholine receptors (nAChRs) are one of the most important families in the ligand-gated ion channel superfamily due to their involvement in primordial brain functions and in several neurodegenerative pathologies. The discovery of new ligands which can bind with high affinity and selectivity to nAChR subtypes is of prime interest in order to study these receptors and to potentially discover new drugs for treating various pathologies. Predatory cone snails of the genus Conus hunt their prey using venoms containing a large number of small, highly structured peptides called conotoxins. Conotoxins are classified in different structural families and target a large panel of receptors and ion channels. Interestingly, nAChRs represent the only subgroup for which Conus has developed seven distinct families of conotoxins. Conus venoms have thus received much attention as they could represent a potential source of selective ligands of nAChR subtypes. We describe the mass spectrometric based approaches which led to the discovery of a novel α-conotoxin targeting muscular nAChR from the venom of Conus ermineus. The presence of several posttranslational modifications complicated the N-terminal sequencing. To discriminate between the different possible sequences, analogs with variable N-terminus were synthesized and fragmented by MS/MS. Understanding the fragmentation pathways in the low m/z range appeared crucial to determine the right sequence. The biological activity of this novel α-conotoxin (α-EIIA) that belongs to the unusual α4/4 subfamily was determined by binding experiments. The results revealed not only its selectivity for the muscular nAChR, but also a clear discrimination between the two binding sites described for this receptor. [less ▲]

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See detailIsolation and pharmacological characterization of AdTx1, a natural peptide displaying specific insurmountable antagonism of the alpha1A-adrenoceptor
Quinton, Loïc ULg; Girard, E.; Maiga, A. et al

in British Journal of Pharmacology (2010), 159

Venoms are a rich source of ligands for ion channels, but very little is known about their capacity to modulate G-protein coupled receptor (GPCR) activity. We developed a strategy to identify novel toxins ... [more ▼]

Venoms are a rich source of ligands for ion channels, but very little is known about their capacity to modulate G-protein coupled receptor (GPCR) activity. We developed a strategy to identify novel toxins targeting GPCRs. Experimental approach: We studied the interactions of mamba venom fractions with a1-adrenoceptors in binding experiments with 3H-prazosin. The active peptide (AdTx1) was sequenced by Edman degradation and mass spectrometry fragmentation. Its synthetic homologue was pharmacologically characterized by binding experiments using cloned receptors and by functional experiments on rabbit isolated prostatic smooth muscle [less ▲]

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See detailIdentification of a novel snake peptide displaying high affinity and antagonist behaviour for the alpha2-adrenoreceptors
Rouget, Céline; Quinton, Loïc ULg; Maïga, Arhamatoulaye et al

in British Journal of Pharmacology (2010), 161

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See detailFourier transform mass spectrometry: A powerful tool for toxin analysis
Quinton, Loïc ULg; Le Caër, Jean-Pierre; Vinh, Joëlle et al

in Toxicon (2006), 47(6), 715-726

The crude venom of Conus virgo was analyzed by Fourier transform mass spectrometry (FTMS) using both nano-electrospray ionization and MALDI. The analyses were performed directly on the crude venom ... [more ▼]

The crude venom of Conus virgo was analyzed by Fourier transform mass spectrometry (FTMS) using both nano-electrospray ionization and MALDI. The analyses were performed directly on the crude venom, without chromatographic separation. The mass fingerprinting of the venom yielded 64 distinct molecular masses in the range 500-4500 Da with two major components at 1328.5142 and 1358.5592 Da. To facilitate the de novo sequencing of these compounds, the disulfide bonds of all components were reduced for the whole venom. The mass accuracy, resolution and sensitivity provided by FTMS were necessary to complete the sequencing of the two new peptides named ViVA and ViVB, that turned out to be conotoxins belonging to the T-superfamily, with the disulfide framework V. The peptides shared 80% similarity and as often observed for this class of compound, they were highly post-translationally modified: amidated C-terminus, pyroglutamic acid residue at the N-terminus and two disulfide bonds. Complementary online nano-LC-nano-ESI-FTMS experiments were undertaken. Among the 130 molecular masses found in the coupling experiments, only 45 were common with those obtained in the direct approach, which means that 21 compounds observed by nano-ESI-FTMS were not detected. This clearly shows that some discriminations against some classes of compounds occur when a chromatographic step is used before mass spectrometry. [less ▲]

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See detailCharacterization of Toxins within Crude Venoms by Combined Use of Fourier Transform Mass Spectrometry and Cloning
Quinton, Loïc ULg; Le Caër, Jean-Pierre; Phan, Gilles et al

in Analytical Chemistry (2005), 77(20), 6630-6639

The standard analytical procedure for screening the proteomic profile of a venom often relies on an appropriate combination of sample extraction, electrophoresis, reversed- phase high-performance liquid ... [more ▼]

The standard analytical procedure for screening the proteomic profile of a venom often relies on an appropriate combination of sample extraction, electrophoresis, reversed- phase high-performance liquid chromatography, mass spectrometry, and Edman degradation. We present in this study a new approach for venom screening based on Fourier transform mass spectrometry (FTMS) analysis directly on the crude venom. The venom chosen is a unique sample from Atractaspis irregularis, a species never studied at the molecular level previously. This snake belongs to the Atractaspidae family that is known to produce highly toxic venoms containing endothelin-like peptides called sarafotoxins (SRTXs). Nanoelectrospray- FTMS spectrum of the crude venom allowed the identification of 60 distinct compounds with molecular masses from 600 to 14 000 Da, which would have been impossible without the resolution of this kind of instrument. De novo sequencing within the entire venom confirmed the sequences of two new families of sarafotoxins, whose precursors had been cloned, and allowed the characterization of a third one. One particularly interesting point was that the propolypeptides appeared processed not in one unique compound, but rather in different length molecules ranging from 15 for the shorter to 30 amino acids for the longer. Moreover, our results clearly establish that in the case of A. irregularis only one copy of mature sarafotoxin emerges from each precursor, which is a totally different organization in comparison of other precursors of SRTXs. [less ▲]

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