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International audience; Phelipanche ramosa is an obligate root-parasitic weed that threatens major crops in central Europe. In order to germinate, it must perceive various structurally divergent host-exuded signals, including isothiocyanates (ITCs) and strigolactones (SLs). However, the receptors involved are still uncharacterized. Here, we identify five putative SL receptors in P. ramosa and show that PrKAI2d3 is involved in the stimulation of seed germination. We demonstrate the high plasticity of PrKAI2d3, which allows it to interact with different chemicals, including ITCs. The SL perception mechanism of PrKAI2d3 is similar to that of endogenous SLs in non-parasitic plants. We provide evidence that PrKAI2d3 enzymatic activity confers hypersensitivity to SLs. Additionally, we demonstrate that methylbutenolide-OH binds PrKAI2d3 and stimulates P. ramosa germination with bioactivity comparable to that of ITCs. This study demonstrates that P. ramosa has extended its signal perception system during evolution, a fact that should be considered for the development of specific and efficient biocontrol methods.

International audience; A library of 26 novel carboxamides deriving from natural fislatifolic acid has been prepared. The synthetic strategy involve dabio-inspired Diels-Aldercycloaddition,followed by functionalisations of the carbonyl moiety. All the compounds were evaluated on Bcl-xL, Mcl-1andBcl-2 proteins. In this series of cyclohexenyl chalcone analogues,six compounds behaved as dua lBcl-xL/Mcl-1 inhibitors in micromolar range and one exhibited sub-micromolar affinities toward Mcl-1andBcl-2.The most potent compounds evaluated on A549 and MCF7cancer cell lines showed moderate cytotoxicities

An l-proline based catalyst with a charged phenyl-pyridium substituent (1) was used to analyze intermediates of an organocatalyzed aldol reaction by infrared multi-photon dissociation (IRMPD) mass spectrometry after transfer into the gas phase via electrospray ionization (ESI). IRMPD spectra were interpreted with the aid of density functional theory (DFT) computations. A structurally restricted enamine species was used as a reference molecule for the calculated vibrational frequencies. A close correlation between theory and experiment was found for the energetically most favoured oxazolidinone structures.

International audience; The chemical difference between DNA and RNA nucleosides is their 2′-hydrogen versus 2′-hydroxyl substituents. Modification of the ribosyl moiety at the 2′-position and 2′-O-methylation in particular, is common among natural post-transcriptional modifications of RNA. 2′-Modification may alter the electronic properties and hydrogen-bonding characteristics of the nucleoside and thus may lead to enhanced stabilization or malfunction. The structures and relative glycosidic bond stabilities of the protonated forms of the 2′-O-methylated purine nucleosides, 2′-O-methyladenosine (Adom) and 2′-O-methylguanosine (Guom), were examined using two complementary tandem mass spectrometry approaches, infrared multiple photon dissociation action spectroscopy and energy-resolved collision-induced dissociation. Theoretical calculations were also performed to predict the structures and relative stabilities of stable low-energy conformations of the protonated forms of the 2′-O-methylated purine nucleosides and their infrared spectra in the gas phase. Low-energy conformations highly parallel to those found for the protonated forms of the canonical DNA and RNA purine nucleosides are also found for the protonated 2′-O-methylated purine nucleosides. Importantly, the preferred site of protonation, nucleobase orientation, and sugar puckering are preserved among the DNA, RNA, and 2′-O-methylated variants of the protonated purine nucleosides. The 2′-substituent does however influence hydrogen-bond stabilization as the 2′-O-methyl and 2′-hydroxyl substituents enable a hydrogen-bonding interaction between the 2′- and 3′-substituents, whereas a 2′-hydrogen atom does not. Further, 2′-O-methylation reduces the number of stable low-energy hydrogen-bonded conformations possible and importantly inverts the preferred polarity of this interaction versus that of the RNA analogues. Trends in the CID50% values extracted from survival yield analyses of the 2′-O-methylated and canonical DNA and RNA forms of the protonated purine nucleosides are employed to elucidate their relative glycosidic bond stabilities. The glycosidic bond stability of Adom is found to exceed that of its DNA and RNA analogues. The glycosidic bond stability of Guom is also found to exceed that of its DNA analogue; however, this modification weakens this bond relative to its RNA counterpart. The glycosidic bond stability of the protonated purine nucleosides appears to be correlated with the hydrogen-bond stabilization of the sugar moiety.

Infrared multiple-photon dissociation (IRMPD) action spectroscopy was performed on the b2 + fragment ion from the protonated PPG tripeptide. Comparison of the experimental infrared spectrum with computed spectra for both oxazolone and diketopiperazine structures indicates that the majority of the fragment ion population has an oxazolone structure with the remainder having a diketopiperazine structure. This result is in contrast with a recent study of the IRMPD action spectrum of the PP b2 + fragment ion from PPP, which was found to be nearly 100% diketopiperazine (Martens et al. Int. J. Mass Spectrom. 2015, 377, 179). The diketopiperazine b2 + ion is thermodynamically more stable than the oxazolone but normally requires a trans/cis peptide bond isomerization in the dissociating peptide. Martens et al. showed through IRMPD action spectroscopy that the PPP precursor ion was in a conformation in which the first peptide bond is already in the cis conformation and thus it was energetically favorable to form the thermodynamically-favored diketopiperazine b2 + ion. In the present case, solution-phase NMR spectroscopy and gas-phase IRMPD action spectroscopy show that the PPGprecursor ion has its first amide bond in a trans configuration suggesting that the third residue is playing an important role in both the structure of the peptide and the associated ring-closure barriers for oxazolone and diketopiperazine formation.

International audience; The deleterious cellular effects of ionizing radiation are well-known, but the mechanisms causing DNA damage are poorly understood. The accepted molecular events involve initial oxidation and deprotonation at guanine sites, triggering hydrogen atom abstraction reactions from the sugar moieties, causing DNA strand breaks. Probing the chemistry of the initially formed radical cation has been challenging. Here, we generate, spectroscopically characterize, and examine the reactivity of the Watson–Crick nucleobase pair radical cation in the gas phase. We observe rich chemistry, including proton transfer between the bases and propagation of the radical site in deoxyguanosine from the base to the sugar, thus rupturing the sugar. This first example of a gas-phase model system providing molecular-level details on the chemistry of an ionized DNA base pair paves the way toward a more complete understanding of molecular processes induced by radiation. It also highlights the role of radical propagation in chemistry, biology, and nanotechnology.

The authors acknowledge support in the form of NSERC (Canada) Discovery Grants to EF, WSH, and TBM and an EPSRC (UK) responsive mode grant to DO’H and NSK is gratefully acknowledged. Experiments have been carried out in which electrospray ionization has been used to generate ionic complexes of all-cis 1,2,3,4,5,6 hexafluorocyclohexane. These complexes were subsequently mass isolated in a quadrupole ion trap mass spectrometer and then irradiated by the tunable infrared output of a free electron laser in the 800-1600 cm−1 range. From the frequency dependence of the fragmentation of the complexes, vibrational signatures of the complexes were obtained. Computational work carried out in parallel reveals that the complexes formed are very strongly bound and are among the most strongly bound complexes of Na+ and Cl− ever observed with molecular species. The dipole moment calculated for the heaxafluorocyclohexane is very large (~7 D) and it appears that the bonding in each of the complexes has a significant electrostatic contribution. Postprint

International audience; Lasso peptides are natural products characterized by a mechanically interlocked topology. The conformation of lasso peptides has been probed in the gas phase using ion mobility–mass spectrometry (IM–MS) which showed differences in the lasso and their unthreaded branched-cyclic topoisomers depending on the ion charge states. To further characterize the evolution of gas phase conformations as a function of the charge state and to assess associated changes in the hydrogen bond network, infrared multiple photon dissociation (IRMPD) action spectroscopy was carried out on two representative lasso peptides, microcin J25 (MccJ25) and capistruin, and their branched-cyclic topoisomers. For the branched-cyclic topoisomers, spectroscopic evidence of a disruption of neutral hydrogen bonds were found when comparing the 3+ and 4+ charge states. In contrast, for the lasso peptides, the IRMPD spectra were found to be similar for the two charge states, suggesting very little difference in gas phase conformations upon addition of a proton. The IRMPD data were thus found consistent and complementary to IM–MS, confirming the stable and compact structure of lasso peptides in the gas phase.

The gas-phase structures of cytosine–Ag+ [CAg]+ and cytosine–Ag+–H2O [CAg–H2O]+ complexes have been studied by mass-selected infrared multiphoton dissociation (IRMPD) spectroscopy in the 900–1800 cm−1 spectral region using the Free Electron Laser facility in Orsay (CLIO). The IRMPD experimental spectra have been compared with the calculated IR absorption spectra of the different low-lying isomers (computed at the DFT level using the B3LYP functional and the 6-311G++(d,p) basis set for C, H, N and O atoms and the Stuttgart effective core potential for Ag). For the [CAg]+ complex, only one isomer with cytosine in the keto-amino (KA) tautomeric form and Ag+ interacting simultaneously with the C(2)[double bond, length as m-dash]O(7) group and N(3) of cytosine was observed. However, the mono-hydration of the complex in the gas phase leads to the stabilization of a two quasi-isoenergetic structure of the [CAg–H2O]+ complex, in which Ag+ interacts with the O atom of the water molecule and with the N(3) or C(2)[double bond, length as m-dash]O(7) group of cytosine. The relative populations of the two isomers determined from the IRMPD kinetics plot are in good agreement with the calculated values. Comparison of these results with those of protonated cytosine [CH]+ and its mono-hydrated complex [CH–H2O]+ shows some interesting differences between H+ and Ag+. In particular, while a single water molecule catalyzes the isomerization reaction in the case of [CH–H2O]+, it is found that in the case of [CAg–H2O]+ the addition of water leads to the stabilization of two isomers separated by small energy barrier (0.05 eV). Fil: Berdakin, Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina Fil: Steinmetz, Vincent. Université Paris Sud; Francia Fil: Maitre, Philippe. Université Paris Sud; Francia Fil: Pino, Gustavo Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina

Diethyl carbonate and dimethyl carbonate are prototype examples of eco-friendly solvents used in lithium-ion batteries. Nevertheless, their degradation products affect both the battery performance and its safety. Therefore, it is of paramount importance to understand the reaction mechanisms involved in the ageing processes. Among those, redox processes are likely to play a critical role. Here we show that radiolysis is an ideal tool to generate the electrolytes degradation products. The major gases detected after irradiation (H2, CH4, C2H6, CO and CO2) are identified and quantified. Moreover, the chemical compounds formed in the liquid phase are characterized by different mass spectrometry techniques. Reaction mechanisms are then proposed. The detected products are consistent with those of the cycling of Li-based cells. This demonstrates that radiolysis is a versatile and very helpful tool to better understand the phenomena occurring in lithium-ion batteries., The degradation of organic solvents used in lithium-ion batteries reduces battery performance. Here, the authors present a radiolysis technique which is not only more efficient than conventional thermally activated ageing methods, but also allows mechanistic analysis of the degradation process.

International audience; Guanine radical cations are formed upon oxidation of DNA. Deoxyguanosine (dG) is used as a model, and the gas-phase infrared (IR) spectroscopic signature and gas-phase unimolecular and bimolecular chemistry of its radical cation, dG˙+, A, which is formed via direct electrospray ionisation (ESI/MS) of a methanolic solution of Cu(NO3)2 and dG, are examined. Quantum chemistry calculations have been carried out on 28 isomers and comparisons between their calculated IR spectra and the experimentally-measured spectra suggest that A exists as the ground-state keto tautomer. Collision-induced dissociation (CID) of A proceeds via cleavage of the glycosidic bond, while its ion–molecule reactions with amine bases occur via a number of pathways including hydrogen-atom abstraction, proton transfer and adduct formation. A hidden channel, involving isomerisation of the radical cation via adduct formation, is revealed through the use of two stages of CID, with the final stage of CID showing the loss of CH2O as a major fragmentation pathway from the reformed radical cation, dG˙+. Quantum chemistry calculations on the unimolecular and bimolecular reactivity are also consistent with A being present as a ground-state keto tautomer.

International audience; Combining electron capture dissociation mass spectrometry and infrared multiple photon dissociation action spectroscopy allows the formation, selection and characterisation of reduced metal complexes containing non-innocent ligands. Zinc complexes containing diazafluorenone ligands have been studied and the localisation of the single electron on the metal atom in the mono-ligated complex has been demonstrated.

Phenylalkylamines of the general formula C6H5(CH2)nNH2 (n = 1-4) have been delivered to the gas phase as protonated species using electrospray ionization. The ions thus formed have been assayed by IRMPD spectroscopy in two different spectroscopic domains, namely, the 600-1800 and the 3000-3500 cm(-1) regions using either an IR free electron laser or a tabletop OPO/OPA laser source. The interpretation of the experimental spectra is aided by density functional theory calculations of candidate species and vibrational frequency analyses. Protonated benzylamine presents a relatively straightforward instance of a single stable conformer, providing a trial case for the adopted approach. Turning to the higher homologues, C6H5(CH2)nNH3(+) (n = 2-4), more conformations become accessible. For each C6H5(CH2)nNH3(+) ion (n = 2-4), the most stable geometry is characterized by cation-π interactions between the positively charged ammonium group and the aromatic π-electronic system, permitted by the folding of the polymethylene chain. The IRMPD spectra of the sampled ions confirm the presence of the folded structures by comparison with the calculated IR spectra of the various possible conformers. An inspection of the NH stretching region is helpful in this regard.

A comprehensive ab initio investigation has been performed on the structure and stability of the isomers of cycloserine and its protonated forms in the unsolvated state. Many conformers of cycloserine in the ketonic (K), enolic (E4 and E2 ), and zwitterionic (Z7 and Z2 ) forms have been characterized. Enols E2 are only a few kilocalories per mole less stable than the K isomers. Enols E4 , as well as Z7 and Z2 zwitterions, are several tens of kilocalories per mole less stable than K. All the above isomeric structures exhibit pronounced isoxazolidine ring puckering, which generates very rich conformeric landscapes. The relative stability of the conformers of K, E2 , and E4 responds essentially to a complex balance between the attractive and repulsive electrostatic interactions among their functional groups. The preferred site of protonation of cycloserine in the gas phase has been also investigated computationally and experimentally by IR multiphoton dissociation (IRMPD) spectroscopy. The most basic center of cycloserine is the N(7) nitrogen atom (proton affinity (PA)=215.3 kcal mol-1 ). Another important basic site is the O(6) oxygen atom (PA=213.0 kcal mol-1 ). Their most populated conformers have been identified by IRMPD spectroscopy. Their predominance responds to the electrostatic interactions among the functional groups of the protonated molecule.

The ESI-formed protonated 2′-deoxycytidine, cytidine, cytarabine, and gemcitabine have been probed using infrared multiphoton dissociation (IRMPD) spectroscopy performed in the 900–2000 cm−1 region at CLIO, the Orsay Free Electron Laser facility, and in the 2800–3800 cm−1 region using a YAG-laser coupled to a table-top optical parametric oscillator/amplifier (OPO/OPA). The IRMPD spectra are compared of the protonated nucleosides with the IR spectra of their B3LYP/6-311++G(d,p)-optimized isomeric forms. The stability at room temperature of some conformers has been investigated by means of ab initio molecular dynamics simulations. The IRMPD spectra are consistent with the formation in the ESI source of both the N3- and the O2-protonated nucleosides. The most favoured members of both families are characterized by the pyrimidine base oriented anti to the furanose moiety. Concerning the O2-protonated nucleosides, IRMPD spectra and thermochemical considerations support the predominant formation of the structures with the proton oriented up relative to the furanose moiety.

The vibrational spectra of ciprofloxacin complexes with monovalent (Li +, Na+, K+, Ag+) and polyvalent (Mg2+, Al3+) metal ions are recorded in the range 1000-1900 cm-1 by means of infrared multiple-photon dissociation (IRMPD) spectroscopy. The IRMPD spectra are analyzed and interpreted in the light of density functional theory (DFT)-based quantum chemical calculations in order to identify the possible structures present under our experimental conditions. For each metal-ciprofloxacin complex, four isomers are predicted, considering different chelation patterns. A good agreement is found between the measured IRMPD spectrum and the calculated absorption spectrum of the most stable isomer for each complex. Metal ion size and charge are found to drive the competition among the different coordination motifs: small size and high charge density metal ions prefer to coordinate the quinolone between the two carbonyl oxygen atoms, whereas large-size metal ions prefer the carboxylate group as a coordination site. In the latter case, an intramolecular hydrogen bond compensates the weaker interaction established by these cations. The role of the metal cation on the stabilization of ionic and nonionic structures of ciprofloxacin is also investigated. It is found that large-size metal ions preferentially stabilize charge separated motifs and that the increase of metal ion charge has a stabilizing effect on the zwitterionic form of ciprofloxacin. © 2012 American Chemical Society.

In this paper, some terms of Artificial Intelligence are defined. Some present and potential applications of knowledge based systems are presented in the field of wine-making. Areas of concern were: multi sensor fusion, prediction by model cooperation, and diagnosis. Artificial intelligence techniques can indeed be applied for aiding the wine-maker in his choices. They facilitate the combination between experience and recent progress in technology. When associated with statistical processing, they allow knowledge sources to be used more effectively. Beyond wine-making, the prospects of artificial intelligence are promising for research and food industry, especially for improving the robustness of measurement systems (multi-sensors, sensors interpreted or validated by models), and for process diagnosis (risk prediction, action proposal)., Certains termes d'Intelligence Artificielle (IA) sont définis dans cette publication. Quelques applications en cours ou potentielles de systèmes fondés sur la connaissance sont présentés dans le domaine de la vinification. Les domaines d'étude sont : la fusion multi-capteurs, la prédiction par coopération de modèles, et le diagnostic. Les techniques IA peuvent aider le vinificateur dans ses choix par une symbiose entre expérience et progrès technologiques. En association avec des traitements statistiques, ces techniques permettent une utilisation plus efficace des sources de connaissances. Au-delà de la vinification, les perspectives de l'intelligence artificielle sont prometteuses en industrie alimentaire, en particulier pour améliorer la robustesse d'un système de mesure (fusion de capteurs, validation d'un capteur par un modèle) ou pour élaborer un diagnostic sur l'évolution d'un procédé (prédiction de risques, proposition d'intervention).