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  • P. Barbier Saint Hilaire, A. Warnet, Y. Gimbert, U. M. Hohenester, G. Giorgi, M. - F. Olivier, F. Fenaille, B. Colsch, C. Junot, et J. - C. Tabet, « Mechanistic study of competitive releases of H2O, NH3 and CO2 from deprotonated aspartic and glutamic acids: Role of conformation », Journal of Chromatography B, vol. 1047, p. 64-74.
    Résumé : The aims of this study were to highlight the impact of minor structural differences (e.g. an aminoacid side chain enlargement by one methylene group), on ion dissociation under collision-induced dissociation conditions, and to determine the underlying chemical mechanisms. Therefore, we compared fragmentations of deprotonated aspartic and glutamic acids generated in negative electrospray ionization. Energy-resolved mass spectrometry breakdown curves were recorded and MS3 experiments performed on an Orbitrap Fusion for high-resolution and high-mass accuracy measurements. Activated fragmentations were performed using both the resonant and non-resonant excitation modes (i.e., CID and HCD, respectively) in order to get complementary information on the competitive and consecutive dissociative pathways. These experiments showed a specific loss of ammonia from the activated aspartate but not from the activated glutamate. We mainly focused on this specific observed loss from aspartate. Two different mechanisms based on intramolecular reactions (similar to those occurring in organic chemistry) were proposed, such as intramolecular elimination (i.e. Ei-like) and nucleophilic substitution (i.e. SNi-like) reactions, respectively, yielding anions as fumarate and α lactone from a particular conformation with the lowest steric hindrance (i.e. with antiperiplanar carboxyl groups). The detected deaminated aspartate anion can then release CO2 as observed in the MS3 experimental spectra. However, quantum calculations did not indicate the formation of such a deaminated aspartate product ion without loss of carbon dioxide. Actually, calculations displayed the double neutral (NH3+CO2) loss as a concomitant pathway (from a particular conformation) with relative high activation energy instead of a consecutive process. This disagreement is apparent since the concomitant pathway may be changed into consecutive dissociations according to the collision energy i.e., at higher collision energy and at lower excitation conditions, respectively. The latter takes place by stabilization of the deaminated aspartate solvated with two residual molecules of water (present in the collision cell). This desolvated anion formed is an α lactone substituted by a methylene carboxylate group. The vibrational excitation acquired by [(D−H)−NH3]−during its isolation is enough to allow its prompt decarboxylation with a barrier lower than 8.4 kJ/mol. In addition, study of glutamic acid-like diastereomers constituted by a cyclopropane, hindering any side chain rotation, confirms the impact of the three-dimensional geometry on fragmentation pathways. A significant specific loss of water is only observed for one of these diastereomers. Other experiments, such as stable isotope labeling, need to be performed to elucidate all the observed losses from activated aspartate and glutamate anions. These first mechanistic interpretations enhance understanding of this dissociative pathway and underline the necessity of studying fragmentation of a large number of various compounds to implement properly new algorithms for de novo elucidation of unknown metabolites.
    Mots-clés : CSOB, Electrospray high-resolution mass spectrometry, POLE 3, Regioselective dissociation, Unexpected cleavage of aspartate anion.

  • J. Blass, J. Brunke, F. Emmerich, C. Przybylski, V. M. Garamus, A. Feoktystov, R. Bennewitz, G. Wenz, et M. Albrecht, « Interactions between shape-persistent macromolecules as probed by AFM », Beilstein Journal of Organic Chemistry, vol. 13, p. 938-951.

  • P. - E. Bodet, I. Salard, C. Przybylski, F. Gonnet, C. Gomila, J. Ausseil, et R. Daniel, « Efficient recovery of glycosaminoglycan oligosaccharides from polyacrylamide gel electrophoresis combined with mass spectrometry analysis », Analytical and Bioanalytical Chemistry, vol. 409, nᵒ 5, p. 1257-1269, 2017.

  • E. Darii, S. Alves, Y. Gimbert, A. Perret, et J. - C. Tabet, « Meaning and consequence of the coexistence of competitive hydrogen bond/salt forms on the dissociation orientation of non-covalent complexes », Journal of Chromatography B, vol. 1047, p. 45-58.
    Résumé : Non-covalent complexes (NCC) between hexose monophosphates (HexP) and arginine (R) were analyzed using ESI MS and MS/MS in negative mode under different (hard, HC and soft, SC) desolvation conditions. High resolution mass spectrometry (HRMS) revealed the presence of different ionic species, namely, homo- and heteromultimers of R and HexP. Deprotonated heterodimers and corresponding sodiated species were enhanced under HC likely due to a decrease in available charge number associated with the reduction of H+/Na+ exchange. The quantum calculations showed that the formation of covalent systems is very little exothermic, therefore, such systems are disfavored. Desolvation dependent CID spectra of deprotonated [(HexP+R)‒H]− complexes demonstrated that they can exist within the hydrogen bond (HB) and salt bridge (SB) forms, yielding either NCC separation or covalent bond cleavages, respectively. Although HB forms are the main species, they cannot survive under HC; therefore, the minor SB forms became detectable. Energy-resolved mass spectrometry (ERMS) experiments revealed diagnostic fragment ions from both SB and HB forms, providing evidence that these isomeric forms are inconvertible. SB formation should result from the ionic interactions of highly acidic group of HexP with strongly basic guanidine group of arginine and thus requires an arginine zwitterion (ZW) form. This was confirmed by quantum calculations. Ion-ion interactions are significantly affected by the presence of sodium cation as demonstrated by the fragmentation patterns of sodiated complex species. Regarding CID data, only SB between protonated amino group of R and deprotonated phosphate group of HexP could be suggested, but the primary amine is not enough basic then, the SB must be fleeting. Nevertheless, the observation of the covalent bond cleavages suggests the presence of structures with a free negative charge able to induce fragmentations. Indeed, according to quantum calculations, solvated salt (SS) systems involving Na+/COO− salt solvated by neutral phosphate and negative charge on sugar ring are preferentially formed.
    Mots-clés : CSOB, POLE 3.

  • G. A. Garcia, H. Dossmann, L. Nahon, S. Daly, et I. Powis, « Identifying and Understanding Strong Vibronic Interaction Effects Observed in the Asymmetry of Chiral Molecule Photoelectron Angular Distributions », ChemPhysChem, vol. 18, nᵒ 5, p. 500-512.
    Résumé : Electron–ion coincidence imaging is used to study chiral asymmetry in the angular distribution of electrons emitted from randomly-oriented enantiomers of two molecules, methyloxirane and trifluoromethyloxirane, upon ionization by circularly polarized VUV synchrotron radiation. Vibrationally-resolved photoelectron circular dichroism (PECD) measurements of the outermost orbital ionization reveal unanticipated large fluctuations in the magnitude of the forward–backward electron scattering asymmetry, including even a complete reversal of direction. Identification and assignment of the vibrational excitations is supported by Franck–Condon simulations of the photoelectron spectra. A previously proposed quasi-diatomic model for PECD is developed and extended to treat polyatomic systems. The parametric dependence of the electronic dipole matrix elements on nuclear geometry is evaluated in the adiabatic approximation. It provokes vibrational level dependent shifts in amplitude and phase, to which the chiral photoelectron angular distributions are especially sensitive. It is shown that single quantum excitation of those vibrational modes, which experience only a relatively small displacement of the ion equilibrium geometry along the normal coordinate and which are then only weakly excited in the Franck–Condon limit, can be accompanied by big shifts in scattering phase; hence the observed big fluctuations in PECD asymmetry for such modes.
    Mots-clés : circular dichroism, CSOB, photoelectron circular dichroism, photoelectron spectroscopy, photoionization, Photophysics, POLE 3.

  • D. Gatineau, A. Memboeuf, A. Milet, R. B. Cole, H. Dossmann, Y. Gimbert, et D. Lesage, « Experimental bond dissociation energies of benzylpyridinium thermometer ions determined by threshold-CID and RRKM modeling », International Journal of Mass Spectrometry.

  • M. N. Godoi, F. de Azambuja, P. D. G. Martinez, N. H. Morgon, V. G. Santos, T. Regiani, D. Lesage, H. Dossmann, R. B. Cole, M. N. Eberlin, et C. R. D. Correia, « Revisiting the Intermolecular Fujiwara Hydroarylation of Alkynes », European Journal of Organic Chemistry, vol. 2017, nᵒ 13, p. 1794-1803.

  • B. Habchi, S. Alves, D. J. - R. Bouveresse, B. Moslah, A. Paris, Y. Lécluse, P. Gauduchon, P. Lebailly, D. N. Rutledge, et E. Rathahao-Paris, « An innovative chemometric method for processing direct introduction high resolution mass spectrometry metabolomic data: independent component–discriminant analysis (IC–DA) », Metabolomics, vol. 13, nᵒ 4, p. 45.
    Résumé : IntroductionTo perform large scale metabolomic analyses, high throughput approaches are required. The direct introduction mass spectrometry (DIMS) approach appears to be very attractive to achieve this goal. However, processing DIMS data is still very challenging due to the large number of samples and the intrinsic complexity of the mass spectra.ObjectivesThe objective of this study is to develop a computational procedure, based on an innovative chemometric method, i.e. Independent component–discriminant analysis (IC–DA), for processing DIMS data.MethodMetabolomic fingerprints were obtained by direct introduction high resolution mass spectrometry (DI-HRMS) analysis of urine samples of subjects that had been professionally exposed to pesticides. Spectral data were processed using the developed IC–DA procedure. Results obtained from this method were compared to those obtained by the conventional Partial least squares–discriminant analysis (PLS–DA). For both the IC–DA and PLS–DA methods, a validation was performed based on a permutation test.ResultIC–DA results enabled a good detection of discriminant variables and a clear discrimination of control samples and exposure classes whereas a less striking discrimination was obtained with PLS–DA. Putative annotation of these variables was performed using metabolomic databases. Targeted correlation analysis was used for the detection of ions associated with the most discriminant variables, consolidating their identity assignment.ConclusionThis study demonstrated the efficiency of IC–DA to discriminate the different exposure groups. As well the improvement of high throughput metabolomic studies was provided by combining DI–HRMS with this new chemometric tool.
    Mots-clés : CSOB, POLE 3.

  • C. K. O'Sullivan, M. Ortiz, A. , M. Debela, M. Svobodova, S. Thorimbert, D. Lesage, R. Cole, et B. Hasenknopf, « PCR Incorporation of Polyoxometalate Modified Deoxynucleotide Triphosphates and Their Application in Molecular Electrochemical Sensing of Yersinia pestis », Chemistry – A European Journal, vol. 23, nᵒ 44, p. 10597–10603.
    Résumé : Redox-labeled nucleotides are of increasing interest for the fabrication of next generation molecular tools and should meet requirements of being thermally stable, sensitive, and compatible with polymerase-mediated incorporation whilst also being electrochemically discriminable. The synthesis and characterization of Keggin and Dawson polyoxometalate-deoxynucleotide (POM-dNTP) bioconjugates linked through 7-deaza-modified purines is described. The modified POM-dNTPs were used for polymerase based amplification of a DNA sequence specific for Yersinia pestis and the amplified DNA detected via an electrochemical DNA sensor. This highlights the potential of polyoxometalates as thermally stable, sensitive and polymerase-compatible redox labels for exploitation in bioanalytical applications.
    Mots-clés : Biosensor, CHEMBIO, CSOB, Electroanalytical Chemistry, GOBS, Labelled nucleotides, PCR, POLE 3, Polyoxometalates.

  • E. Rathahao-Paris, S. Alves, L. Debrauwer, J. - P. Cravedi, et A. Paris, « An efficient data-filtering strategy for easy metabolite detection from the direct analysis of a biological fluid using Fourier transform mass spectrometry », Rapid Communications in Mass Spectrometry, vol. 31, nᵒ 6, p. 485-494.
    Résumé : Rationale High-throughput analyses require an overall analytical workflow including not only a robust and high-speed technical platform, but also dedicated data-processing tools able to extract the relevant information. This work aimed at evaluating post-acquisition data-mining tools for selective extraction of metabolite species from direct introduction high-resolution mass spectrometry data. Methods Investigations were performed on spectral data in which seven metabolites of vinclozolin, a dicarboximide fungicide containing two chloride atoms, were previously manually identified. The spectral data obtained from direct introduction (DI) and high-resolution mass spectrometry (HRMS) detection were post-processed by plotting the mass defect profiles and applying various data-filtering methods based on accurate mass values. Results Exploration of mass defect profiles highlighted, in a specific plotting region, the presence of compounds containing common chemical elements and pairs of conjugated and non-conjugated metabolites resulting from classical metabolic pathways. Additionally, the judicious application of mass defect and/or isotope pattern filters removed many interfering ions from DI-HRMS data, greatly facilitating the detection of vinclozolin metabolites. Compared with previous results obtained by manual data treatment, three additional metabolites of vinclozolin were detected and putatively annotated. Conclusions Tracking simultaneously several specific species could be efficiently performed using data-mining tools based on accurate mass values. The selectivity of the data extraction was improved when the isotope filter was used for halogenated compounds, facilitating metabolite ion detection even for low-abundance species. Copyright © 2016 John Wiley & Sons, Ltd.
    Mots-clés : CSOB, POLE 3.

  • T. S. Rodrigues, D. Lesage, W. A. da Silva, R. B. Cole, G. Ebeling, J. Dupont, H. C. B. de Oliveira, M. N. Eberlin, et B. A. D. Neto, « Charge-tagged N-heterocyclic carbenes (NHC): Direct transfer from ionic liquid solutions and long-lived nature in the gas phase », Journal of The American Society for Mass Spectrometry, vol. 28, nᵒ 6, p. 1021-1029.

  • A. Tomer, F. Wyrwalski, C. Przybylski, J. - F. Paul, E. Monflier, M. Pera-Titus, et A. Ponchel, « Facile preparation of Ni/Al 2 O 3 catalytic formulations with the aid of cyclodextrin complexes: Towards highly active and robust catalysts for the direct amination of alcohols », Journal of Catalysis, vol. 356, p. 111-124, 2017.


  • L. Bai, F. Wyrwalski, M. Safariamin, R. Bleta, J. - F. Lamonier, C. Przybylski, E. Monflier, et A. Ponchel, « Cyclodextrin-cobalt (II) molecule-ion pairs as precursors to active Co3O4/ZrO2 catalysts for the complete oxidation of formaldehyde: Influence of the cobalt source », Journal of Catalysis, vol. 341, p. 191-204.

  • M. Barbazanges, E. Caytan, D. Lesage, C. Aubert, L. Fensterbank, V. Gandon, et C. Ollivier, « Chiral Phosphate in Rhodium-Catalyzed Asymmetric [2+2+2] Cycloaddition: Ligand, Counterion, or Both? », Chemistry – A European Journal, vol. 22, nᵒ 25, p. 8553-8558.
    Résumé : Investigations based on NMR spectroscopy, mass spectrometry, and DFT calculations shed light on the metallic species generated in the rhodium-catalyzed asymmetric [2+2+2] cycloaddition reaction between diynes and isocyanates with the chiral phosphate TRIP. The catalytic mixture comprising [{Rh(cod)Cl}2], 1,4-diphenylphosphinobutane (dppb), and Ag(S)-TRIP actually gives rise to two species, both having an effect on the stereoselectivity. One is a rhodium(I) complex in which TRIP is a weakly coordinating counterion, whereas the other is a bimetallic Rh/Ag complex in which TRIP is a strongly coordinating X-type ligand.
    Mots-clés : chirality, CSOB, cycloaddition, homogeneous catalysis, ligand effects, MACO, POLE 1, POLE 3, Rhodium.

  • T. T. Boukerche, S. Alves, P. Le Faouder, A. Warnet, J. Bertrand-Michel, M. Bouchekara, M. Belbachir, et J. - C. Tabet, « Atypical cleavage of protonated N-fatty acyl amino acids derived from aspartic acid evidenced by sequential MS(3) experiments », Amino Acids, vol. 48, nᵒ 12, p. 2717-2729.
    Résumé : Lipidomics calls for information on detected lipids and conjugates whose structural elucidation by mass spectrometry requires to rationalization of their gas phase dissociations toward collision-induced dissociation (CID) processes. This study focused on activated dissociations of two lipoamino acid (LAA) systems composed of N-palmitoyl acyl coupled with aspartic and glutamic acid mono ethyl esters (as LAA(*D) and LAA(*E)). Although in MS/MS, their CID spectra show similar trends, e.g., release of water and ethanol, the [(LAA(*D/*E)+H)-C2H5OH](+) product ions dissociate via distinct pathways in sequential MS(3) experiments. The formation of all the product ions is rationalized by charge-promoted cleavages often involving stepwise processes with ion isomerization into ion-dipole prior to dissociation. The latter explains the maleic anhydride or ketene neutral losses from N-palmitoyl acyl aspartate and glutamate anhydride fragment ions, respectively. Consequently, protonated palmitoyl acid amide is generated from LAA(*D), whereas LAA(*E) leads to the [*E+H-H2O](+) anhydride. The former releases ammonia to provide acylium, which gives the C n H(2n-1) and C n H(2n-3) carbenium series. This should offer structural information, e.g., to locate either unsaturation(s) or alkyl group branching present on the various fatty acyl moieties of lipo-aspartic acid in further studies based on MS (n) experiments.
    Mots-clés : CSOB, ESI/MS n, Ion–dipole, N-fatty-acyl amino-acid, POLE 3, Regioselectivity.

  • J. E. Boulicault, S. Alves, et R. B. Cole, « Negative Ion MALDI Mass Spectrometry of Polyoxometalates (POMs): Mechanism of Singly Charged Anion Formation and Chemical Properties Evaluation », Journal of the American Society for Mass Spectrometry, vol. 27, nᵒ 8, p. 1301-1313.
    Résumé : MALDI-MS has been developed for the negative ion mode analysis of polyoxometalates (POMs). Matrix optimization was performed using a variety of matrix compounds. A first group of matrixes offers MALDI mass spectra containing abundant intact singly charged anionic adduct ions, as well as abundant in-source fragmentations at elevated laser powers. A relative ranking of the ability to induce POM fragmentation is found to be: DAN > CHCA > CNA > DIT> HABA > DCTB > IAA. Matrixes of a second group provide poorer quality MALDI mass spectra without observable fragments. Sample preparation, including the testing of salt additives, was performed to optimize signals for a model POM, POMc12, the core structure of which bears four negative charges. The matrix 9-cyanoanthracene (CNA) provided the best signals corresponding to singly charged intact POMc12 anions. Decompositions of these intact anionic species were examined in detail, and it was concluded that hydrogen radical-induced mechanisms were not prevalent, but rather that the observed prompt fragments originate from transferred energy derived from initial electronic excitation of the CNA matrix. Moreover, in obtained MALDI mass spectra, clear evidence of electron transfer to analyte POM species was found: a manifestation of the POMs ability to readily capture electrons. The affinity of polyanionic POMc12 toward a variety of cations was evaluated and the following affinity ranking was established: Fe3+ > Al3+ > Li+ > Ga3+ > Co2+ > Cr3+ > Cu2+ > [Mn2+, Mg2+] > [Na+, K+]. Thus, from the available cationic species, specific adducts are preferentially formed, and evidence is given that these higher affinity POM complexes are formed in the gas phase during the early stages of plume expansion.Graphical Abstractᅟ
    Mots-clés : CSOB, POLE 3.

  • M. C. Bridoux, A. Schwarzenberg, S. Schramm, et R. B. Cole, « Combined use of direct analysis in real-time/Orbitrap mass spectrometry and micro-Raman spectroscopy for the comprehensive characterization of real explosive samples », Analytical and Bioanalytical Chemistry, vol. 408, nᵒ 21, p. 5677-5687.
    Résumé : Direct Analysis in Real Time (DART™) high-resolution Orbitrap™ mass spectrometry (HRMS) in combination with

    Raman microscopy was used for the detailed molecular level characterization of explosives including not only the charge but also the complex matrix of binders, plasticizers, polymers, and other possible organic additives. A total of 15 defused military weapons including grenades, mines, rockets, submunitions, and mortars were examined. Swabs and wipes were used to collect trace (residual) amounts of explosives and their organic constituents from the defused military weapons and micrometer-size explosive particles were transferred using a vacuum suction-impact collection device (vacuum impactor) from wipe and swap samples to an impaction plate made of carbon. The particles deposited on the carbon plate were then characterized using micro-Raman spectroscopy followed by DART-HRMS providing fingerprint signatures of orthogonal nature. The optical microscope of the micro-Raman spectrometer was first used to localize and characterize the explosive charge on the impaction plate which was then targeted for identification by DART-HRMS analysis in both the negative and positive modes. Raman spectra of the explosives TNT, RDX and PETN were acquired from micrometer size particles and characterized by the presence of their characteristic Raman bands obtained directly at the surface of the impaction plate nondestructively without further sample preparation. Negative mode DART-HRMS confirmed the types of charges contained in the weapons (mainly TNT, RDX, HMX, and PETN; either as individual components or as mixtures). These energetic compounds were mainly detected as deprotonated species [M–H]−, or as adduct [M + 35Cl]−, [M + 37Cl]−, or [M + NO3]− anions. Chloride adducts were promoted in the heated DART reagent gas by adding chloroform vapors to the helium stream using an “in-house” delivery method. When the polarity was switched to positive mode, DART-HRMS revealed a very complex distribution of polymeric binders (mainly polyethylene glycols and polypropylene glycols), plasticizers (e.g., dioctyl sebacate, tributyl phosphate), as well as wax-like compounds whose structural features could not be precisely assigned. In positive mode, compounds were identified either as protonated molecules or ammonium adduct species. These results clearly demonstrate the complementarity of micro-Raman microscopy combined with DART-MS. The former technique provides structural information on the type of explosives present at the surface of the sample, whereas the latter provides not only a confirmation of the nature of the explosive charge but also useful additional information regarding the nature of the complex organic matrix of binders, plasticizers, polymers, oils, and potentially other organic additives and contaminants present in the sample. Combining these two techniques provides a powerful tool for the screening, comprehensive characterization, and differentiation of particulate explosive samples for forensic sciences and homeland security applications.Graphical AbstractComprehensive characterization of explosive particles collected from swipe samples by micro-Raman and DART™-HRMS
    Mots-clés : CSOB, POLE 3.

  • Q. Dumont, M. Bárcenas, H. Dossmann, I. Bailloux, C. Buisson, N. Mechin, A. Molina, F. Lasne, N. S. Rannulu, et R. B. Cole, « Improved Steroids Detection and Evidence for Their Regiospecific Decompositions Using Anion Attachment Mass Spectrometry », Analytical Chemistry, vol. 88, nᵒ 7, p. 3585-3591.
    Résumé : Nonpolar anabolic steroids are doping agents that typically do not provide strong signals by electrospray ionization-mass spectrometry (ESI-MS) owing especially to the low polarity of the functional groups present. We have investigated the addition of anions, in ammonium salt form, to anabolic steroid samples as ionization enhancers and have confirmed that lower instrumental limits of detection (as low as 10 ng/mL for fluoxymesterone-M) are obtained by fluoride anion attachment mass spectrometry, as compared to ESI(+)/(−) or atmospheric pressure photoionization (APPI)(+). Moreover, collision-induced decomposition (CID) spectra of precursor fluoride adducts of the bifunctional steroid “reduced pregnenolone” (containing two hydroxyl groups) and its d4-analogue provide evidence of regiospecific decompositions after attachment of fluoride anion to a specific hydroxyl group of the steroid. This type of charting of specific CID reaction pathways can offer value to selected reaction monitoring experiments (SRM) as it may result in a gain in selectivity in detection as well as in improvements in quantification.
    Mots-clés : CSOB, POLE 3.

  • B. Guan et R. B. Cole, « The Background to Electrospray », in The Encyclopedia of Mass Spectrometry, Boston: Elsevier, p. 132-140.
    Résumé : This article traces the development of electrospray back to its earliest beginnings. Many readers may be surprised to learn that descriptions of the electrostatic attraction of liquids to surfaces appear in the scientific literature as early as the year 1600, and that true electrospray experiments are documented to have been performed in the eighteenth century. Progress in the development of electrospray is detailed through these earliest observations and subsequent ingenious applications, mathematical descriptions, and, finally, coupling to mass analyzer instrumentation.
    Mots-clés : CSOB, Electrospray development, Electrospray history, Geoffrey Taylor, Harold Ransburg, Jean-Antoine Nollet, John Ellicott, John William Strutt, John Zeleny, Lord Kelvin, Lord Rayleigh, Malcolm Dole, POLE 3, Sir Thomas Browne, Stephen Gray, W. A. Macky, William Gilbert, William Henley, William Thomson.

  • B. Habchi, S. Alves, A. Paris, D. N. Rutledge, et E. Rathahao-Paris, « How to really perform high throughput metabolomic analyses efficiently? », TrAC Trends in Analytical Chemistry, vol. 85, Part C, p. 128-139.
    Résumé : High-throughput analyses are based on technologies characterized by their rapidity, simplicity, sensitivity, robustness, low cost and high efficiency. They offer the potential for screening a large number of samples per day, which cannot be done using classical methods. High-throughput analyses have shown their feasibility and efficiency in multidisciplinary fields such as drug screening, bioassays of compound against mycobacteria. Another successful application is based on direct introduction mass spectrometry for the analysis of very complex organic materials in petroleomics. High-throughput analyses appear to be very attractive in metabolomics, which aims to study the interface between the chemical universe and biology, to detect general metabolic disruptions induced by external factors through a metabolite profiling approach. In this review, we focus on high-throughput metabolomics using high resolution mass spectrometry (HRMS). Specifically, performances and limits of available analytical techniques dedicated to high-throughput analyses, including sample introduction methods, HRMS and data processing tools are discussed.
    Mots-clés : CSOB, Data processing, DIMS, FTMS, High-throughput analyses, metabolomics, POLE 3.

  • F. Jaroschik, A. Simonneau, G. Lemière, K. Cariou, N. Agenet, H. Amouri, C. Aubert, J. - P. Goddard, D. Lesage, M. Malacria, Y. Gimbert, V. Gandon, et L. Fensterbank, « Assessing Ligand and Counterion Effects in the Noble Metal Catalyzed Cycloisomerization Reactions of 1,6-Allenynes: a Combined Experimental and Theoretical Approach », ACS Catalysis, vol. 6, nᵒ 8, p. 5146-5160.
    Résumé : 1,6-Allenynes are useful mechanistic probes in noble-metal catalysis, since they can give rise to very distinct products in a highly selective fashion. Various cycloisomerization reactions have been described, and discrete mechanisms have been postulated. Of particular interest, whereas Alder-ene types of products can be obtained in a variety of ways using noble-metal catalysts (Au, Pt, Rh, ...), hydrindienes have been reported solely with gold and platinum under specific conditions. It was shown in a previous study that this intriguing transformation required the presence of chloride ligands at the active catalytic species. Herein, the factors governing the fate of 1,6-allenynes under cycloisomerization conditions have been studied more thoroughly, revealing a much more complex scenario. The nature of ligands, counterions, and metals was examined, showing that hydrindienes can be isolated in the absence of halides, using electron-rich, bulky triorganophosphines or carbene ligands. This crucial finding could also be used to access hydrindienes in high yields, not only with gold or platinum but also with silver. On the basis of mass spectrometry, NMR spectroscopy, and computations, refined mechanistic scenarios have been put forward, also rationalizing counterion effects. Notably, a metal vinylidene intermediate has been proposed for the formation of the hydrindiene derivatives. Finally, in the presence of tris((triphenylphosphine)gold)oxonium tetrafluoroborate as catalyst, a new pathway has been unveiled, involving gold alkyne σ,π complexes and leading to previously unobserved [2 + 2] cycloaddition compounds.
    Mots-clés : ARC, CSOB, MACO, POLE 1, POLE 2, POLE 3.

  • D. Lesage, J. Blu, J. - C. Tabet, et Y. Gimbert, « Intermolecular versus intramolecular Pauson-Khand reaction in gas phase: Limitation and feasibility », Journal of Organometallic Chemistry, vol. 809, p. 7-13.

  • A. Lombana, C. Rinfray, F. Volatron, G. Izzet, N. Battaglini, S. Alves, P. Decorse, P. Lang, et A. Proust, « Surface Organization of Polyoxometalate Hybrids Steered by a 2D Supramolecular PTCDI/Melamine Network », The Journal of Physical Chemistry C, vol. 120, nᵒ 5, p. 2837-2845.
    Résumé : A 2D supramolecular honeycomb network built on hydrogen bonding of perylene-3,4,9,10-tetracarboxylic acid diimide (PTCDI) and 1,3,5-triazine-2,4,6-triamine (Melamine) has been self-assembled on Au(111) by a solution processed method. The ability of the porous network to host functional molecular oxides or polyoxometalates (POMs) has been investigated using a functionalized species [PW11O39Ge{p-C6H4-C≡C–C6H4-NHC(O) (CH2)4{-CH(CH2)2S-S-}}]4– (KWGe[S-S]): this inorganic/organic hybrid built on a Keggin-type POM core and an organic tether incorporating a thioctic acid function has been designed to enhance the host–guest interaction by the formation of covalent Au–S bonds. XPS analysis confirmed the presence of the POMs that are covalently held onto the surface. Probed by STM operating under ambient conditions, the spatial organization of the POMs display some reminiscence of the organic template, while monitoring the POM deposition at various immersion times by PM-IRRAS showed that the POM raising at the substrate is fostered.
    Mots-clés : CSOB, E-POM, POLE 2, POLE 3.

  • C. Przybylski, J. M. Benito, V. Bonnet, C. O. Mellet, et J. M. García Fernández, « Deciphering of polycationic carbohydrate based non-viral gene delivery agents by ESI-LTQ-Orbitrap using CID/HCD pairwise tandem mass spectrometry », RSC Adv., vol. 6, nᵒ 82, p. 78803-78817.

  • C. Przybylski, J. M. Benito, V. Bonnet, C. O. Mellet, et J. M. García Fernández, « Toward a suitable structural analysis of gene delivery carrier based on polycationic carbohydrates by electron transfer dissociation tandem mass spectrometry », Analytica Chimica Acta, vol. 948, p. 62-72.

  • E. Rathahao-Paris, S. Alves, C. Junot, et J. - C. Tabet, « High resolution mass spectrometry for structural identification of metabolites in metabolomics », Metabolomics, vol. 12, nᵒ 1, p. 10.
    Résumé : High resolution mass spectrometry (HRMS) is increasingly used to produce metabolomics data. Thanks to its high mass resolution and mass measurement accuracy, it is also very useful for metabolite identification. Nevertheless, a rigorous methodology is required. This manuscript describes different steps involved in the structural elucidation of metabolites and demonstrates the utility of HRMS for such purpose. After a brief overview of HRMS performances in terms of mass measurement accuracy, peak resolution, isotopic clusters/patterns and the instrumentation used, the first section is devoted to the data processing generally performed to reduce the data set size. Based on the mass accuracy measurements, different post-acquisition data processing procedures have been developed for complex mixture analysis and can be used in metabolomics. The second section describes protocols used to process putative metabolite annotations or identifications with HRMS data, based on elemental composition determined from accurately measured m/z value and mass spectral databases. Non-classical approaches are also proposed for tentative structure elucidation of unknown metabolites. Finally, limitations of the proposed workflow for metabolite structure elucidation are discussed and possible improvements are proposed.
    Mots-clés : CSOB, POLE 3.

  • C. Rinfray, V. Brasiliense, G. Izzet, F. Volatron, S. Alves, C. Combellas, F. Kanoufi, et A. Proust, « Electron Transfer to a Phosphomolybdate Monolayer on Glassy Carbon: Ambivalent Effect of Protonation », Inorganic Chemistry, vol. 55, nᵒ 14, p. 6929-6937.
    Résumé : The polyoxomolybdate hybrid TBA3[PMo11O39{Sn(C6H4)C≡C(C6H4)N2}] KMoSn[N2+] was prepared through Sonogashira-type coupling between TBA4[PMo11O39{Sn(C6H4)I}] KMoSn[I] and an excess of 3,3-diethyl-1-(4-ethynylphenyl)triaz-1-ene bearing a protected diazonium function, followed by its deprotection by the addition of trifluoroacetic acid (TFA). This enlarges the family of organic–inorganic polyoxomolybdate-based hybrids, which has been far less investigated than their related polyoxotungstates. The diazonium function allows for the electrochemical grafting on glassy carbon, and the KMoSn-modified electrode was further probed by cyclic voltammetry. The PMo11Sn core was found to be highly sensitive to protonation, and five bielectronic proton-coupled electron transfer processes were detected in the presence of an excess of TFA, thus corresponding to the injection of up to 10 electrons in the potential range between 0.15 and −0.45 V/SCE. The gain observed in the thermodynamic potentials is however detrimental to the apparent kinetics of the electron transfer, which drops from 500 s–1 in the absence of acid to 12 s–1 in the presence of an excess of TFA.
    Mots-clés : CSOB, E-POM, POLE 2, POLE 3.

  • S. Sladkevich, A. - L. Dupont, M. Sablier, D. Seghouane, et R. B. Cole, « Understanding paper degradation: identification of products of cellulosic paper decomposition at the wet-dry “tideline” interface using GC-MS », Analytical and Bioanalytical Chemistry, vol. 408, nᵒ 28, p. 8133-8147.
    Résumé : Cellulose paper degradation products forming in the “tideline” area at the wet-dry interface of pure cellulose paper were analyzed using gas chromatography-electron ionization-mass spectrometry (GC-EI-MS) and high-resolution electrospray ionization-mass spectrometry (ESI-MS, LTQ Orbitrap) techniques. Different extraction protocols were employed in order to solubilize the products of oxidative cellulose decomposition, i.e., a direct solvent extraction or a more laborious chromophore release and identification (CRI) technique aiming to reveal products responsible for paper discoloration in the tideline area. Several groups of low molecular weight compounds were identified, suggesting a complex pathway of cellulose decomposition in the tidelines formed at the cellulose-water-oxygen interface. Our findings, namely the appearance of a wide range of linear saturated carboxylic acids (from formic to nonanoic), support the oxidative autocatalytic mechanism of decomposition. In addition, the identification of several furanic compounds (which can be, in part, responsible for paper discoloration) plus anhydro carbohydrate derivatives sheds more light on the pathways of cellulose decomposition. Most notably, the mechanisms of tideline formation in the presence of molecular oxygen appear surprisingly similar to pathways of pyrolytic cellulose degradation. More complex chromophore compounds were not detected in this study, thereby revealing a difference between this short-term tideline experiment and longer-term cellulose aging.
    Mots-clés : CSOB, POLE 3.


  • A. M. Debela, M. Ortiz, V. Beni, S. Thorimbert, D. Lesage, R. B. Cole, C. K. O'Sullivan, et B. Hasenknopf, « Biofunctionalization of Polyoxometalates with DNA Primers, Their Use in the Polymerase Chain Reaction (PCR) and Electrochemical Detection of PCR Products », Chemistry – A European Journal, vol. 21, nᵒ 49, p. 17721-17727.
    Résumé : The bioconjugation of polyoxometalates (POMs), which are inorganic metal oxido clusters, to DNA strands to obtain functional labeled DNA primers and their potential use in electrochemical detection have been investigated. Activated monooxoacylated polyoxotungstates [SiW11O39{Sn(CH2)2CO}]8− and [P2W17O61{Sn(CH2)2CO}]6− have been used to link to a 5′-NH2 terminated 21-mer DNA forward primer through amide coupling. The functionalized primer was characterized by using a battery of techniques, including electrophoresis, mass spectrometry, as well as IR and Raman spectroscopy. The functionality of the POM-labeled primers was demonstrated through hybridization with a surface-immobilized probe. Finally, the labeled primers were successfully used in the polymerase chain reaction (PCR) and the PCR products were characterized by using electrophoresis.
    Mots-clés : CHEMBIO, CSOB, DNA, DNA Primers, Electrochemistry, GOBS, Nucleic Acid Hybridization, POLE 3, polymerase chain reaction, Polyoxometalates, Redox chemistry, Tungsten Compounds.

  • K. Jeanne Dit Fouque, H. Lavanant, S. Zirah, J. Lemoine, S. Rebuffat, J. - C. Tabet, A. Kulesza, C. Afonso, P. Dugourd, et F. Chirot, « Gas-phase conformations of capistruin – comparison of lasso, branched-cyclic and linear topologies », Rapid Communications in Mass Spectrometry, vol. 29, nᵒ 15, p. 1411-1419.
    Résumé : Rationale Capistruin is a peptide synthesized by Burkholderia thailandensis E264, which displays a lasso topology. This knot-like structure confers interesting properties to peptides (e.g. antibacterial). Therefore, it is important to evaluate the sensitivity of structural characterization methods to such topological constraints. Methods Ion mobility mass spectrometry (IMS-MS) experiments, using both drift tube and travelling wave instruments, were performed on lasso capistruin and on peptides with the same sequence, but displaying a branched-cyclic (un-threaded) or linear topology. Molecular dynamics (MD) simulations were then performed to further interpret the IMS results in terms of conformation. Results The collision cross sections (CCSs) measured via IMS for the different forms of capistruin were found to be similar, despite their different topologies for the doubly charged species, but significant differences arise as the charge state is increased. MD simulations for the doubly charged linear peptide were consistent with the hypothesis that salt bridges are present in the gas phase. Moreover, through CCS measurements for peptides with site-specific mutations, the arginine residue at position 11 was found to play a major role in the stabilization of compact structures for the linear peptide. Conclusions Differences in peptide topologies did not yield marked signatures in their respective IMS spectra. Such signatures were only visible for relatively high charge states, that allow Coulomb repulsion to force unfolding. At low charge states, the topologically unconstrained linear form of capistruin was found to adopt charge solvation-constrained structures, possibly including salt bridges, with CCSs comparable to those measured for the topologically constrained lasso form. Copyright © 2015 John Wiley & Sons, Ltd.
    Mots-clés : CSOB, POLE 3.

  • Y. Jiang, J. A. Madsen, V. Farutin, J. C. Lansing, et R. B. Cole, « High fidelity approach for proteomic scale enrichment and identification of N-termini », International Journal of Mass Spectrometry, vol. 391, p. 115-122, nov. 2015.
    Résumé : A novel workflow was designed for the large-scale identification of protein N-terminal sequences. The workflow started with converting lysine to homoarginine, followed by reaction with sulfonation of N-termini by 4-sulfophenyl isothiocyanate (SPITC). Upon trypsin digestion, the SPITC modified N-terminal peptides were enriched by electrostatic repulsion hydrophilic interaction (ERLIC) chromatography in which the internal and C-terminal peptides eluted at the void volume, and the SPITC peptides were retained in the column due to the hydrophilicity and electrostatic attraction of the sulfonyl group to the stationary phase. Upon higher-energy collisional induced dissociation (HCD) SPITC peptides in ESI generated predominately y-type ion series; such simplification of spectra enables the identification of N-termini with high confidence. The appearance of b1 + SPITC product ions upon HCD further boosts the confidence for N-terminal identifications. This method was applied to an Escherichia coli cell lysate, thus allowing the identification of 358 high confidence N-terminal peptides representing 274 distinct E. coli proteins as certain proteins were found to have multiple N-terminal peptides due to cleavage from various cellular enzymes. Confidence in N-terminal assignments is further heightened since 224 of the unique proteins identified from N-terminal peptides were also identified in the analysis of flow-through fractions.
    Mots-clés : CSOB, ERLIC enrichment, N-termini proteomics, POLE 3, SPITC modification.

  • D. Lesage, G. Barozzino-Consiglio, R. Duwald, C. Fressigné, A. Harrison-Marchand, K. F. Faull, J. Maddaluno, et Y. Gimbert, « A Lithium Amide Protected Against Protonation in the Gas Phase: Unexpected Effect of LiCl », The Journal of Organic Chemistry, vol. 80, nᵒ 12, p. 6441-6446.
    Résumé : In cold THF and in the presence of LiCl, a lithium pyrrolidinylamide forms a 1:1 mixed aggregate, which is observed directly by ESI-MS. Gas-phase protonation of this species leads to selective transfer of H+ to the chlorine, suggesting that LiCl shields the amide nitrogen and prevents its direct protonation.
    Mots-clés : CSOB, POLE 3.

  • J. - P. Mbakidi, F. Brégier, T. - S. Ouk, R. Granet, S. Alves, E. Rivière, S. Chevreux, G. Lemercier, et V. Sol, « Magnetic Dextran Nanoparticles That Bear Hydrophilic Porphyrin Derivatives: Bimodal Agents for Potential Application in Photodynamic Therapy », ChemPlusChem, vol. 80, nᵒ 9, p. 1416-1426.
    Résumé : This study reports the chemical synthesis of a class of dextran superparamagnetic nanoparticles that bear hydrophilic porphyrin units covalently grafted by a click chemistry reaction in aqueous solution. Magnetic nanoparticles are used in magnetic resonance imaging (MRI) and hyperthermia, and the grafting of hydrophilic photosensitizers (PS) leads to elaborate new multifunctional platforms for potential diagnostic and targeted photodynamic therapy (PDT). The therapeutic potential for PDT of these nanoparticles is evaluated in vitro against the HaCaT cell line. The results show that these new multicharged nanomagnets—in particular, those that bear cationic porphyrins—show a significant uptake and an interesting photocytotoxic activity toward HaCaT cells. The whole series of these synthesized PS are massively incorporated inside HaCat cells and associated with mitochondria.
    Mots-clés : click chemistry, CSOB, Magnetic properties, nanoparticles, photodynamic therapy, POLE 3, porphyrinoids.

  • M. Pérot-Taillandier, C. Afonso, Q. Enjalbert, R. Antoine, P. Dugourd, R. B. Cole, J. - C. Tabet, S. Rebuffat, et S. Zirah, « Electron detachment/photodetachment dissociation of lasso peptides », International Journal of Mass Spectrometry, vol. 390, p. 91-100.
    Résumé : Lasso peptides are bioactive peptides produced by bacteria, characterized by a mechanically interlocked topology where the C-terminal tail of the peptide is threaded through and trapped within an N-terminal macrolactam ring. The structural characterization of lasso peptides and differentiation from their unthreaded topoisomers by mass spectrometry are challenging tasks. We previously explored the fragmentation mechanisms of lasso peptides in positive ion mode and showed several signatures of the lasso topology under collision induced dissociation (CID) and electron capture dissociation. Here we analyzed the dissociation of the multiply-deprotonated microcin J25 (MccJ25), a 21-residue lasso peptide produced by Escherichia coli, together with its non-lasso topoisomer and several variants generated by site-directed mutagenesis, under different modes of activation. The fragmentation patterns obtained by CID for the threaded and unthreaded structures were very similar. By contrast, electron detachment dissociation (EDD) as well as activated-electron photodetachment dissociation (a-EPD) revealed very different dissociation pathways for the two topoisomers. The doubly deprotonated topoisomers showed a different deprotonation pattern, Tyr20 residue being deprotonated for MccJ25 only, yielding the singly charged [c19−C2H4O] product ion. MccJ25 also triggered several two-peptide product ions diagnostic of the lasso topology, including the [(c8)*(z2)] species, which could be maintained by either a covalent or a non-covalent linkage.
    Mots-clés : CSOB, Electron detachment dissociation, Electron photodetachment dissociation, Lasso peptides, POLE 3.

  • B. P. Pozniak et R. B. Cole, « Perspective on Electrospray Ionization and Its Relation to Electrochemistry », Journal of The American Society for Mass Spectrometry, vol. 26, nᵒ 3, p. 369-385.
    Résumé : The phenomenon of electrospraying of liquids is presented from the perspective of the electrochemistry involved. Basics of current and liquid flow in the capillary and spray tip are discussed, followed by specifics of charging and discharging of the sprayed liquid surface. Fundamental theories and numerical modeling relating electrospray current to solution and spray parameters are described and then compared with our own experimentally obtained data. The method of mapping potentials and currents inside the electrospray capillary by using an inserted electrically-isolated small wire probe electrode is discussed in detail with illustrations from new and published data. Based on these experimentally obtained results, a new mathematical model is derived. The introduced “nonlinear resistor electrospray capillary model” divides the electrospray capillary into small sections, adds their contributions, and then, by transition to infinitely small section thickness, produces analytical formulas that relate current and potential maps to other properties of the electrospraying liquid: primarily conductivity and current density. The presentation of the model is undertaken from an elementary standpoint, and it offers the possibility to obtain quantitative information regarding operating parameters from typical analytical systems subjected to electrospray. The model stresses simplicity and ease of use; examples applying experimental data are shown and some predictions of the model are also presented. The developed nonlinear resistor electrospray capillary model is intended to provide a new quantitative basis for improving the understanding of electrochemical transformations occurring in the electrospray emitter. A supplemental material section gives full derivation of the model and discusses other consequences.Graphical Abstractᅟ
    Mots-clés : CSOB, POLE 3.

  • B. Quéméner, J. Vigouroux, E. Rathahao, J. C. Tabet, A. Dimitrijevic, et M. Lahaye, « Negative electrospray ionization mass spectrometry: a method for sequencing and determining linkage position in oligosaccharides from branched hemicelluloses », Journal of Mass Spectrometry, vol. 50, nᵒ 1, p. 247-264.
    Résumé : Xyloglucans of apple, tomato, bilberry and tamarind were hydrolyzed by commercial endo β-1-4-D-endoglucanase. The xylo-gluco-oligosaccharides (XylGos) released were separated on CarboPac PA 200 column in less than 15 min, and, after purification, they were structurally characterized by negative electrospray ionization mass spectrometry using a quadrupole time-of-flight (ESI-Q-TOF), a hybrid linear ion trap (LTQ)/Orbitrap and a hybrid quadrupole Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometers. In order to corroborate the fragmentation routes observed on XylGos, some commercial galacto-manno-oligosaccharides (GalMOs) and glucurono-xylo-oligosaccharides were also studied. The fragmentation pathways of the ionized GalMos were similar to those of XylGos ones. The product ion spectra were mainly characterized by prominent double cleavage (D) ions corresponding to the entire inner side chains. The directed fragmentation from the reducing end to the other end was observed for the main glycosylated backbone but also for the side-chains, allowing their complete sequencing. Relevant cross-ring cleavage ions from 0,2Xj -type revealed to be diagnostic of the 1-2-linked- glycosyl units from XylGos together with the 1-2-linked glucuronic acid unit from glucuronoxylans. Resonant activation in the LTQ Orbitrap allowed not only determining the type of all linkages but also the O-acetyl group location on fucosylated side-chains. Moreover, the fragmentation of the different side chains using the MSn capabilities of the LTQ/Orbitrap analyzer also allowed differentiating terminal arabinosyl and xylosyl substituents inside S and U side-chains of XylGos, respectively. The CID spectra obtained were very informative for distinction of isomeric structures differing only in their substitution pattern. These features together makes the fragmentation in negative ionization mode a relevant and powerful technique useful to highlight the subtle structural changes generally observed during the development of plant organs such as during fruit ripening and for the screening of cell wall mutants with altered hemicellulose structure. Copyright © 2015 John Wiley & Sons, Ltd.
    Mots-clés : CSOB, endo β-1-4 endoglucanase, hemicellulose, HPAEC, negative ESI-MS, POLE 3, xyloglucans.

  • S. Schramm, D. Léonço, C. Hubert, J. - C. Tabet, et M. Bridoux, « Development and validation of an isotope dilution ultra-high performance liquid chromatography tandem mass spectrometry method for the reliable quantification of 1,3,5-Triamino-2,4,6-trinitrobenzene (TATB) and 14 other explosives and their degradation products in environmental water samples », Talanta, vol. 143, p. 271-278.
    Résumé : A comprehensive method for the determination and characterization of 15 common explosive compounds in water samples by ultra-high pressure liquid chromatography–atmospheric pressure chemical ionization-tandem mass spectrometry (APCI-MS/MS) is presented. The method allows the determination of 10 nitroaromatics, two nitroamines and three nitrate ester compounds. Among these, 1,3,5-Triamino-2,4,6-trinitrobenzene (TATB) was quantified and detected for the first time in our knowledge at trace levels (0.2 µg/L). Furthermore, the collision induced dissociation (CID) mass spectrum of TATB is discussed and a fragmentation mechanism is proposed. The signal for each explosive was normalized by isotopically-enriched congeners used as internal standards. The limits of detection (LOD) reached 20 ng/L, depending on the type of energetic molecule, which are adequate for water samples and the linearity was verified from 1.4 to 2 orders of magnitude. The sensitivity of the UHPLC–APCI-MS/MS approach allows direct injection of aqueous samples without preceding extraction for concentration. Besides, the method displays a good reliability with low signal suppression in various matrices such as spring water, mineral water, acidified water or ground water. The effectiveness of the method is demonstrated by the analysis of underground water samples containing traces of explosives from test fields in France.
    Mots-clés : Chromatography, CSOB, Explosive, mass spectrometry, Nitroaromatic compounds, POLE 3, TATB.

  • A. Schwarzenberg, J. - C. Tabet, R. B. Cole, X. Machuron-Mandard, et H. Dossmann, « New insights into dissociation of deprotonated 2,4-dinitrotoluene by combined high-resolution mass spectrometry and density functional theory calculations », Rapid Communications in Mass Spectrometry, vol. 29, nᵒ 1, p. 29-34.
    Résumé : RATIONALE 2,4-Dinitrotoluene (2,4-DNT) is a nitroaromatic explosive which is commonly found in environmental samples close to training points, firing places, and manufacturers. Mass spectrometry analysis of this compound shows one main product ion that distinguishes it from the other isomers of DNT. We present here a detailed mechanistic study on the formation of this ion. METHODS 2,4-DNT was analyzed using negative electrospray ionization high-resolution mass spectrometry (ESI-HRMS) using a linear ion trap quadrupole LTQ-Orbitrap XL mass spectrometer. Collision-induced dissociation (CID) experiments were performed on the [M–H]– ion obtained. Density functional theory (DFT) calculations were used to support experimental observations. RESULTS Fragmentation of deprotonated 2,4-DNT [M–H]– (m/z 181) yields a main product ion at m/z 116. The mechanism of formation of this diagnostic product ion is not obvious and it has never been rationalized. Calculations were performed to probe different mechanistic variants, which are discussed in this work. CONCLUSIONS Analysis of possible pathways to form the m/z 116 ion from the m/z 181 precursor shows that its formation is likely to proceed first via NO• loss, followed by eliminations of H2O and then HO•. Copyright © 2014 John Wiley & Sons, Ltd.
    Mots-clés : CSOB, POLE 3.

  • J. Shraberg, S. W. Rick, N. Rannulu, et R. B. Cole, « A study of procyanidin binding to Histatin 5 using Electrospray Ionization Tandem Mass Spectrometry (ESI-MS/MS) and molecular simulations », Physical Chemistry Chemical Physics, vol. 17, nᵒ 18, p. 12247-12258.
    Résumé : Tannins act as antioxidants, anticarcinogens, cardio-protectants, anti-inflammatory and anti-microbial agents and bind to salivary peptides by hydrophilic and hydrophobic mechanisms. Electrospray Ionization Mass Spectrometry (ESI-MS) has been used to assess both hydrophilic and hydrophobic components of noncovalent binding in protein complexes. In the present study, direct infusion Electrospray-Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (ES-FTICR MS) is used to assess relative binding affinities of procyanidin tannin stereoisomers for salivary peptides arising from aqueous solutions. The condensed tannins procyanidin B1, B2, B3, and B4 demonstrate significantly different binding affinities for the salivary peptide Histatin 5. Rigid docking combined with molecular dynamics optimization is used to investigate procyanidin–Histatin 5 binding mechanisms and as a basis to rationalize trends found in the corresponding ES-FTICR MS experiments. The relative binding affinities of the four procyanidin rotamers are different in the gas and liquid phases. The simulation results indicate that many of the same contact points are made in both phases, but there is a increase in strong electrostatic interactions and an decrease in π–π contacts upon transfer from the liquid to the gas phase. The simulations reveal that the tannin interactions can make close contacts with a variety of amino acid residues on the peptide.
    Mots-clés : CSOB, POLE 3.

  • V. P. Stankov-Jovanović, M. D. Ilić, V. D. Mitić, T. M. Mihajilov-Krstev, S. R. Simonović, S. D. Nikolić Mandić, J. C. Tabet, et R. B. Cole, « Secondary metabolites of Seseli rigidum: Chemical composition plus antioxidant, antimicrobial and cholinesterase inhibition activity », Journal of Pharmaceutical and Biomedical Analysis, vol. 111, p. 78-90.
    Résumé : Extracts of different polarity obtained from various plant parts (root, leaf, flower and fruit) of Seseli rigidum were studied by different antioxidant assays: DPPH and ABTS radical scavenging activity, by total reducing power method as well as via total content of flavonoids and polyphenols. Essential oils of all plant parts showed weak antioxidant characteristics. The inhibitory concentration range of the tested extracts, against bacteria Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus cereus, and fungi Candida albicans and Aspergillus niger was 0.01–1.50 mg/mL and of a microbicidal 0.02–3.00 mg/mL. In the interaction with cholinesterase, all essential oils proved effective as inhibitors. The highest percentage of inhibition versus human and horse cholinesterase was shown by root essential oil (38.20% and 48.30%, respectively) among oils, and root hexane extract (40.56% and 50.65% respectively). Essential oils and volatile components of all plant parts were identified by GC, GC–MS and headspace/GC–MS. Statistical analysis of the ensemble of results showed that the root essential oil composition differed significantly from essential oils of other parts of the plant. Taking into account all of the studied activities, the root hexane extract showed the best overall properties. By means of high performance liquid chromatography coupled to high resolution mass spectrometry, the 30 most abundant constituents were identified in extracts of different polarity. The presence of identified constituents was linked to observed specific biological activities, thus designating compounds potentially responsible for each exhibited activity.
    Mots-clés : Antimicrobial activity, antioxidant activity, Cholinesterase inhibition, CSOB, POLE 3, Secondary metabolites, Seseli rigidum.

  • T. Tripković, C. Charvy, S. Alves, A. D. Lolić, R. M. Baosić, S. N. Nikolić-Mandic, et J. C. Tabet, « Electrospray ionization linear trap quadrupole Orbitrap in analysis of old tempera paintings: application to nineteenth-century Orthodox icons », European Journal of Mass Spectrometry, vol. 21, nᵒ 4, p. 679-692.

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