The effect of nitrogen (III) oxide on direct synthesis of concentrated nitric acid

The effect of nitrogen (III) oxide on the process of dinitrogen tetroxide separation in a dephlegmator during preparation of a "crude mixture" (HNO3–N2O4–N2O3–NO2–NO–H2O) in the production of concentrated nitric acid by direct synthesis was studied in this work. The dependence of crystallization onset on the composition of the N2O4–N2O3 mixture and temperature was determined. The refrigerant capable of maintaining the optimal temperature of the N2O4 extraction was suggested. The absence of nitrogen (III) oxide and nitrogen (I) oxide in the autoclave acid was confirmed.

Complexity of the eukaryotic dolichol-linked oligosaccharide scramblase suggested by activity correlation profiling mass spectrometry

The oligosaccharide required for asparagine (N)-linked glycosylation of proteins in the endoplasmic reticulum (ER) is donated by the glycolipid Glc3Man9GlcNAc2-PP-dolichol. Remarkably, whereas glycosylation occurs in the ER lumen, the initial steps of Glc3Man9GlcNAc2-PP-dolichol synthesis generate the lipid intermediate Man5GlcNAc2-PP-dolichol (M5-DLO) on the cytoplasmic side of the ER. Glycolipid assembly is completed only after M5-DLO is translocated to the luminal side. The membrane protein (M5-DLO scramblase) that mediates M5-DLO translocation across the ER membrane has not been identified, despite its importance for N-glycosylation. Building on our ability to recapitulate scramblase activity in proteoliposomes reconstituted with a crude mixture of ER membrane proteins, we developed a mass spectrometry-based 'activity correlation profiling' approach to identify scramblase candidates in the yeast Saccharomyces cerevisiae. Data curation prioritized six polytopic ER membrane proteins as scramblase candidates, but reconstitution-based assays and gene disruption in the protist Trypanosoma brucei revealed, unexpectedly, that none of these proteins is necessary for M5-DLO scramblase activity. Our results instead strongly suggest that M5-DLO scramblase activity is due to a protein, or protein complex, whose activity is regulated at the level of quaternary structure.

Toward a New Way for the Valorization of Miscanthus Biomass Produced on Metal-Contaminated Soils Part 2: Miscanthus-Based Biosourced Catalyst: Design, Preparation, and Catalytic Efficiency in the Synthesis of Moclobemide

The conception of two biosourced catalysts (biocatalysts) using stems of miscanthus from the first part of this study are described herein. The temperature and the process used to extract metals from plant as mixture of Lewis acids were investigated in detail and proved to be essential in the design of the biosourced catalysts and their catalytic efficiency. One part of the crude mixture of Lewis acids extracted from the aerial parts of miscanthus plants was used without further treatment as a homogeneous biocatalyst (M1), and the other part was supported on montmorillonite K10 to provide a heterogeneous biocatalyst (MM1). M1 and MM1 were next tested in the synthesis of moclobemide (main ingredient of a drug used to treat depression) and led to excellent yield. Additional comparative experiments with different commercial metallic salts (NaCl, KCl, CaCl2, MgCl2, CuCl2, ZnCl2, FeCl2, FeCl3, MnCl2, and AlCl3) and their mixtures were carried out and underlined the importance of the multimetallic synergy on catalytic activity. Finally, a comparison of this new synthetic method assisted by the biosourced catalyst with the previously described procedures to access moclobemide was realized by calculating their green chemistry metrics. This study revealed that the use of the biosourced catalyst led to one of the greenest synthetic methods described today to produce moclobemide.

Characterization of Sunflower Oil Extracts from the Lichen Usnea barbata

The increasing global emergence of multidrug resistant (MDR) pathogens is categorized as one of the most important health problems. Therefore, the discovery of novel antimicrobials is of the utmost importance. Lichens provide a rich source of natural products including unique polyketides and polyphenols. Many of them display pharmaceutical benefits. The aim of this study was directed towards the characterization of sunflower oil extracts from the fruticose lichen, Usnea barbata. The concentration of the major polyketide, usnic acid, was 1.6 mg/mL extract as determined by NMR analysis of the crude mixture corresponding to 80 mg per g of the dried lichen. The total phenolics and flavonoids were determined by photometric assays as 4.4 mg/mL (gallic acid equivalent) and 0.27 mg/mL (rutin equivalent) corresponding to 220 mg/g and 13.7 mg/g lichen, respectively. Gram-positive (e.g., Enterococcus faecalis) and Gram-negative bacteria, as well as clinical isolates of infected chickens were sensitive against these extracts as determined by agar diffusion tests. Most of these activities increased in the presence of zinc salts. The data suggest the potential usage of U. barbata extracts as natural additives and mild antibiotics in animal husbandry, especially against enterococcosis in poultry.

Complexity of the eukaryotic dolichol-linked oligosaccharide scramblase suggested by activity correlation profiling mass spectrometry

The canonical pathway of N-linked protein glycosylation in yeast and humans involves transfer of the oligosaccharide moiety from the glycolipid Glc3Man9GlcNAc2-PP-dolichol to select asparagine residues in proteins that have been translocated into the lumen of the endoplasmic reticulum (ER). Synthesis of Glc3Man9GlcNAc2-PP-dolichol occurs in two stages, producing first the key intermediate Man5GlcNAc2-PP-dolichol (M5-DLO) on the cytoplasmic face of the ER, followed by translocation of M5-DLO across the ER membrane to the luminal leaflet where the remaining glycosyltransfer reactions occur to complete the structure. Despite its critical importance for N-glycosylation, the scramblase protein that mediates the translocation of M5-DLO across the ER membrane has not been identified. Building on our ability to recapitulate scramblase activity in large unilamellar proteoliposomes reconstituted with a crude mixture of ER membrane proteins, we developed a mass spectrometry-based ‘activity correlation profiling’ approach to identify scramblase candidates in the yeast Saccharomyces cerevisiae. Curation of the activity correlation profiling data prioritized six polytopic ER membrane proteins as scramblase candidates, but reconstitution-based assays and gene disruption in the protist Trypanosoma brucei revealed, unexpectedly, that none of these proteins were necessary for M5-DLO scramblase activity. Our results instead suggest the possibility that the M5-DLO scramblase may be a protein, or protein complex, whose activity is regulated at the level of quaternary structure. This key insight will aid future attempts to identify the scramblase.

Study on the Lithiation Reaction of 3-Diisopropylcarbamoyl-N-pivaloylphenylethylamine

As a continuation of our earlier studies on the lithiation-based synthesis of 8-methoxy-, 8-fluoro- and 8-chloro-3,4-dihydroisoquinoline, a similar approach was investigated for the preparation of the 8-diisopropylcarbamoyl congener. The corresponding N-pivaloyl phenylethylamine key intermediate was prepared via four new bifunctional intermediates in high overall yield. Lithiation of this intermediate followed by quenching with dimethylformamide led to a mixture: beside the desired compound containing the formyl moiety in the common ortho position of the two aromatic substituents, the isomer formylated in the other ortho position of the carbamoyl moiety was surprisingly obtained as the major product. The crude mixture could finally be transformed under acidic conditions to the target compound, 8-diisopropylcarbamoyl-substituted 3,4-dihydroisoquinoline, albeit in a low yield.

Considerations when quantitating protein abundance by immunoblot

The development of the immunoblot to detect and characterize a protein with an antisera, even in a crude mixture, was a breakthrough with wide-ranging and unpredictable applications across physiology and medicine. Initially, this technique was viewed as a tool for qualitative, not quantitative, analyses of proteins because of the high number of variables between sample preparation and detection with antibodies. Nonetheless, as the immunoblot method was streamlined and improved, investigators pushed it to quantitate protein abundance in unpurified samples as a function of treatment, genotype, or pathology. This short review, geared at investigators, reviewers, and critical readers, presents a set of issues that are of critical importance for quantitative analysis of protein abundance: 1) Consider whether tissue samples are of equivalent integrity and assess how handling between collection and assay influences the apparent relative abundance. 2) Establish the specificity of the antiserum for the protein of interest by providing clear images, molecular weight markers, positive and negative controls, and vendor details. 3) Provide convincing evidence for linearity of the detection system by assessing signal density as a function of sample loaded. 4) Recognize that loading control proteins are rarely in the same linear range of detection as the protein of interest; consider protein staining of the gel or blot. In summary, with careful attention to sample integrity, antibody specificity, linearity of the detection system, and acceptable loading controls, investigators can implement quantitative immunoblots to convincingly assess protein abundance in their samples.