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51.
Joly L Antoine R Broyer M Dugourd P Lemoine J 《Journal of mass spectrometry : JMS》2007,42(6):818-824
UV photodissociation (UVPD) at 262 nm has been carried out on protonated tyrosyl-containing peptides formed by trypsin digestion of apo-transferrin. Under UVPD, the main event is the fragmentation of the C(alpha)-C(beta) bond of the tyrosyl residues leading to a radical ion 107 Da below the precursor ion. The dissociation rate of this specific cleavage appears to be strongly dependent on the peptide sequence and is more prominent on the singly protonated species than on the doubly protonated state. The fragmentation spectra resulting from collisional activation of the protonated even-electron native peptides and of the odd-electron radical species prepared by UVPD are dominated by y-type backbone cleavages. A comparison of their respective y-ion pattern shows complementarities since the combination of both increases the sequence coverage of the peptide sequence. The specific detection of the neutral loss of 107 Da from peptides witnesses the content of at least one tyrosyl residue and, though preliminary, is proposed as a potential new filtering strategy during protein database searching. 相似文献
52.
Calvo F Chirot F Albrieux F Lemoine J Tsybin YO Pernot P Dugourd P 《Journal of the American Society for Mass Spectrometry》2012,23(7):1279-1288
Following a recent effort [J. Am. Soc. Mass Spectrom. 23, 386-396 (2012)], we continue to explore computational methodologies for generating molecular conformations to support collisional cross sections suggested by ion mobility measurements. Here, adaptively biased molecular dynamics (ABMD) simulations are used to sample the configuration space and to achieve flat-histogram sampling along the reaction coordinates of the first two moments of the gyration tensor. The method is tested and compared with replica-exchange simulations on triply-protonated bradykinin and on a larger 25-residue peptide. It is found to have a much higher efficiency for producing large sets of conformations in a broad range of diffusion cross-sections, whereas it does not compete with conventional replica-exchange molecular dynamics in locating the lowest-energy structure. Nevertheless, the broad sampling obtained from the ABMD method allows to quantitatively correlate the diffusion cross-section Ω with other geometric order parameters that have simpler interpretation. The strong correlations found between the diffusion cross-section and the radius of gyration, the surface area and the volume of the convex hull suggest an optimal template for accurately mimicking the variations of Ω in a broad range of conformations, using only geometrical information and doing so at a very moderate computational cost. The existence of such a correlation is confirmed on the much larger protein α-lactalbumin. 相似文献
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Lemoine J Cabanes-Macheteau M Bardor M Michalski JC Faye L Lerouge P 《Rapid communications in mass spectrometry : RCM》2000,14(2):100-104
Fluorophore-assisted carbohydrate electrophoresis (FACE) is a fast and efficient analytical method which is now widely used in glycobiology for the separation and quantification of free or glycoprotein-released oligosaccharides. However, since identification by FACE of N-glycan structures is only based on their electrophoretic mobility after labelling with 8-aminonaphthalene-1,3, 6-trisulfonic acid (ANTS), co-migration of derived glycans on gel could occur which may result in erroneous structural assignments. As a consequence, a protocol was developed for the fast and efficient matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectrometric analysis of ANTS-labelled N-glycans. N-Glycans were isolated from plant and mammalian glycoproteins, reductively aminated with the charged fluorophore 8-aminonaphthalene-1, 3, 6-trisulfonic acid (ANTS) and separated using high resolution polyacrylamide gel electrophoresis. The ANTS-labelled glycans were eluted from FACE gel slices and then analysed by MALDI-TOF mass spectrometry in negative ion mode. Using 3-aminoquinoline containing 2.5 mM citrate NH(4)(+) as matrix, neutral N-linked N-glycans, as well as labelled sialylated oligosaccharides, were found to be easily detected in the 2-10 picomole range giving rise to ?M - H(-) ions. 相似文献
56.
Jean‐Claude Daran Pascale Lemoine Bernard Viossat 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(4):m210-m212
The asymmetric unit of the title compound, [Zn(C10H6NO2)2(C12H8N2)]·1.5C3H7NO, contains one monomeric zinc complex and 1.5 disordered dimethylformamide solvate molecules. The Zn atom is coordinated to one 1,10‐phenanthroline ligand and to two isoquinolinecarboxylate anions (IQC?) via their N and O atoms. The complex exhibits a distorted octahedral geometry around the ZnII atom, with the apical positions occupied by the O atoms of the IQC? ligands. The Zn atom lies 0.049 (1) Å out of the basal plane. The crystal packing is characterized by several hydrogen bonds. 相似文献
57.
Bernhard Spengler Dieter Kirsch Raimund Kaufmann Jrme Lemoine 《Journal of mass spectrometry : JMS》1994,29(12):782-787
Post-source decay matrix-assisted laser desorption ionization (PSD-MALDI) of sodium ion-attached branched oligosaccharides derived from glycoproteins was demonstrated as a method of structure analysis by reflectron time-of-flight (TOF) mass spectrometry. Mono-, di- and triantennary structures were investigated. The fragmentation patterns of these (structurally related) substances as obtained in the positive-ion mode showed characteristic differences correlated with branching sites and linkage positions. Two-bond ring cleavages as known from fast atom bombardment/collision-induced dissociation and IR laser desorption mass spectrometry were also observed. Internal fragment ions formed by up to four consecutive cleavages were obtained with high intensity, allowing the branching structure of complex carbohydrates to be identified. PSD-MALDI of oligosaccharides is characterized by high sensitivity, very good signal-to-noise ratios and high reproducibility of fragmentation patterns and signal intensities. 相似文献
58.
Mohammad A. Halim Marion Girod Luke MacAleese Jérôme Lemoine Rodolphe Antoine Philippe Dugourd 《Journal of the American Society for Mass Spectrometry》2016,27(3):474-486
Characterization of acidic peptides and proteins is greatly hindered due to lack of suitable analytical techniques. Here we present the implementation of 213 nm ultraviolet photodissociation (UVPD) in high-resolution quadrupole-Orbitrap mass spectrometer in negative polarity for peptide anions. Radical-driven backbone fragmentation provides 22 distinctive fragment ion types, achieving the complete sequence coverage for all reported peptides. Hydrogen-deficient radical anion not only promotes the cleavage of Cα–C bond but also stimulates the breaking of N–Cα and C–N bonds. Radical-directed loss of small molecules and specific side chain of amino acids are detected in these experiments. Radical containing side chain of amino acids (Tyr, Ser, Thr, and Asp) may possibly support the N–Cα backbone fragmentation. Proline comprising peptides exhibit the unusual fragment ions similar to reported earlier. Interestingly, basic amino acids such as Arg and Lys also stimulated the formation of abundant b and y ions of the related peptide anions. Loss of hydrogen atom from the charge-reduced radical anion and fragment ions are rationalized by time-dependent density functional theory (TDDFT) calculation, locating the potential energy surface (PES) of ππ* and repulsive πσ* excited states of a model amide system. 相似文献
59.
Robé E Perlikowska W Lemoine C Diab L Vincendeau S Mikolajczyk M Daran JC Gouygou M 《Dalton transactions (Cambridge, England : 2003)》2008,(21):2894-2898
Diphosphine sulfides derived from 2,2'-biphosphole have been efficiently synthesized in an enantiomerically pure form by a four step synthetic sequence. These S,S-ligands were used for the first time in Pd-catalyzed asymmetric allylic alkylation. Good yields and enantiomeric excess up to 73% were obtained. 相似文献
60.