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About 25% of open reading frames in fully sequenced genomes are estimated to encode transmembrane proteins that represent valuable targets for drugs. However, the global analysis of membrane proteins has been proven to be problematic, e.g., because of their very amphiphilic nature. In this paper, we show that the recently published Protein Sequence Tag (PST) technology combined with an efficient sample preparation is a powerful method to perform protein analysis of highly enriched membrane fractions. The PST approach is a gel-free proteomics tool for the analysis of proteins, which relies on a "sampling" strategy by isolating N-terminal protein sequence tags from cyanogen bromide cleaved proteins. The identification of these N-terminal PST peptides is based on LC-MS/MS. The effectiveness of the technology is demonstrated for a membrane fraction, which was isolated from crude mitochondria of yeast after alkaline sodium carbonate treatment. The PST approach performed on this fraction analyzed 148 proteins, whereas 84% are identified as membrane proteins. More interestingly, among these membrane proteins 56% are predicted to be of low abundance. These encouraging results are an important step toward the development of a quantitative PST approach (qPST) for the differential display of membrane protein analysis.

A novel method for the isolation of protein sequence tags to identify proteins in a complex mixture of hydrophobic proteins is described. The PST (Protein Sequence Tag) technology deals with the isolation and MS/MS based identification of one N-terminal peptide from each polypeptide fragment generated by cyanogen bromide cleavage of a mixture of proteins. PST sampling takes place after sub-cellular fractionation of a complex protein mixture to give enrichment of mitochondrial proteins. The method presented here combines effective sample preparation with a novel peptide isolation protocol involving chemical and enzymatic cleavage of proteins coupled to chemical labeling and selective capture procedures. The overall process has been very successful for the analysis of complex mixtures of hydrophobic proteins, particularly membrane proteins. This method substantially reduces the complexity of a protein digest by "sampling" the peptides present in the digest. The sampled digest is amenable to analysis by liquid chromatography tandem mass spectrometry (LC-MS/MS). Methods of "sampling" protein digests have great value' if they can provide sufficient information to identify substantially all of the proteins in the sample while reducing the complexity of the sample to maximize the efficient usage of LC-MS/MS capacity. The validity of the process is demonstrated for mitochondrial samples from S. cerevisiae. The proteins identified by the PST technology are compared to the proteins identified by the conventional technology 2-D gel electrophoresis as a control.

A convenient, low cost, large scale synthesis of (L)-β-cyclopropylalanine is reported.

International audience; FTIR spectroscopy was applied to the investigation of the nitrosyl complexes formed with the extra-framework iron species in Fe-ferrierite (Fe-FER). To clarify the loading effect oil the nature Of file species formed. six ferrierites with Fe loadings varying between 0 and 3.7 wt % were prepared via ionic exchange and investigated. A Fe/SiO(2) and a Fe-FER sample containing iron oxide were also Studied for comparison purposes. Adsorption of NO on Fe-FER (containing no iron oxide species) gives different nitrosyl species. and different iron sites call be evidenced depending on the iron concentration. The bands are assigned to mononitrosyl oil iron whose oxidation state is determined to be +2 thanks to Mossbauer spectroscopy. In particular, one specific Fe(2+)-cation (typical of a highly loaded sample) appears to be easily converted to Fe(3+) upon oxygen treatment, which makes these sites excellent candidates for catalytically active redox sites.

Comparative proteome profiling using stable isotope peptide labelling and mass spectrometry has emerged as a promising strategy. Here, we show the broad potential of our proprietary protein sequence tag (PST) technology.* A special feature of PST is its ability to detect a wide variety of proteins including the pharmaceutically relevant membrane and nuclear proteins. This procedure addresses a similar number of proteins, compared to the multidimensional protein identification technology approach, but offers additionally a quantitative analysis with its recently developed quantitative PST version.

A novel MS/MS-based analysis strategy using isotopomer labels, referred to as "tandem mass tags" (TMTs), for the accurate quantification of peptides and proteins is described. The new tags are designed to ensure that identical peptides labeled with different TMTs exactly comigrate in all separations. The tags require novel methods of quantification analysis using tandem mass spectrometry. The new tags and analysis methods allow peptides from different samples to be identified by their relative abundance with greater ease and accuracy than other methods. The new TMTs permit simultaneous determination of both the identity and relative abundances of peptide pairs using a collision induced dissociation (CID)-based analysis method. Relative abundance measurements made in the MS/MS mode using the new tags are accurate and sensitive. Compared to MS-mode measurements, a very high signal-to-noise ratio is achieved with MS/MS based detection. The new tags should be applicable to a wide variety of peptide isolation methods.

The Sm₈Cr₂Si₆N₂O₂₄ oxynitride has an apatite-like structure. The parameters of the hexagonal unit cell are a = 9,469 (5) and c = 6,890 (4) Å ; the space group is P6₃. The structure affinement has been carried to a R factor = 0,036 for 717 independent non-zero reflexions recorded with an automated diffractometer. The two Cr (III) atoms and two samarium atoms are distributed together among two 2 b crystallographic sites instead of occupying them in an ordered way., L'oxynitrure Sm₈Cr₂Si₆N₂O₂₄ possède une structure de type apatite. Les paramètres de la maille hexagonale sont a = 9,469 (5) et c = 6,890 (4) Å ; le groupe spatial est P6₃. L'affinement de la structure a été mené jusqu'à un facteur R = 0,036 pour 717 réflexions indépendantes non nulles mesurées grâce à un difïractomètre automatique. Les deux atomes de Cr (III) et deux atomes de samarium se répartissent sur deux sites cristallographiques 2 b au lieu de les occuper de façon ordonnée., Maunaye Marcel, Hamon Christian, L'Haridon Paul, Laurent Yves. Composés à structure apatite. IV. Étude structurale de l'oxynitrure Sm8Cr2Si6N2O24. In: Bulletin de la Société française de Minéralogie et de Cristallographie, volume 99, 4, 1976. pp. 203-205.

New possibilities for synthesis result from the introduction of nitrogen in the anionic sublattice of the apatites. They have been investigated from the structure of Sm₁₀Si₆N₂O₂₄. Because the nitrogen atoms are placed in the tetrahedral environment of the silicon atoms, their number may have a higher value. New compounds can thus be obtained where lanthanides and transition elements in a high oxydation state are simultaneously present. A lot of possibilities have been studied by considering the different crystallographic sites and their environment rather than the substitution mechanisms based on chemical analogies., L'introduction d'azote dans le réseau anionique des apatites ouvre de nouvelles perspectives de synthèse. Elles ont été envisagées à partir de la structure de Sm₁₀Si₆N₂O₂₄. La participation des atomes d'azote à l'environnement du silicium permet de prévoir une augmentation importante de leur nombre. Il est alors possible de préparer des composés dans lesquels interviennent simultanément des lanthanides et des éléments de transition dans un état d'oxydation élevé. On a étudié un ensemble de possibilités en considérant les divers sites cristallographiques et leur environnement plutôt qu'uniquement des mécanismes de substitutions fondés sur des analogies chimiques., Lang Jean, Marchand Roger, Hamon Christian, L'Haridon Paul, Guyader Jean. Composés à structure apatite. II. — Cristallochimie des silico-apatites azotées. In: Bulletin de la Société française de Minéralogie et de Cristallographie, volume 98, 5, 1975. pp. 284-288.