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ESI‐MS2 and Anti‐inflammatory Studies of Cyclopropanic Triterpenes. UPLC‐ESI‐MS and MS2 Search of Related Metabolites from Donella ubanguiensis
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Louis P. Sandjo Marcus V.P. dos Santos Nascimento Layzon A.L. da Silva Antonio C.M. Munhoz Luiz A.E. Pollo Maique W. Biavatti Bonaventure T. Ngadjui Till Opatz Tania S. Fröde 《Phytochemical analysis : PCA》2017,28(1):27-41
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In this study the analysis and confirmation of flumequine enantiomers in rat plasma by ultra‐fast liquid chromatography coupled with electron spray ionization mass spectrometry (using propranolol as an internal standard [IS]) was developed and validated. Plasma samples were prepared by liquid–liquid extraction using methyl tert‐butyl ether as the extraction solvent. Direct resolution of the R‐ and S‐isomers was performed on a CHIRALCEL OJ‐RH column (4.6 × 150 mm, 5 μm) using acetonitrile / 0.1% formic acid / 1 mM ammonium acetate as the mobile phase. Detection was operated by electron spray ionization in the selected ion monitoring and positive ion mode. The target ions at m/z 262.1 and m/z 260.1 were selected for the quantification of the enantiomers and IS, respectively. The linear range was 0.5–500 ng/mL. The precisions (coefficient of variation, CV%) and recoveries were 1.43–8.68 and 94.24–106.76%, respectively. The lowest quantitation limit for both enantiomers is 0.5 ng/mL, which is sensitive enough to be applied to sample analysis in other related studies. 相似文献
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Takumi Takata Seongmin Ha Tamaki Koide Noriko Fujii 《Protein science : a publication of the Protein Society》2020,29(4):941-951
Recent studies have suggested that the isomerization/racemization of aspartate residues in proteins increases in aged tissues. One such residue is Asp151 in lens‐specific αA‐crystallin. Although many isomerization/racemization sites have been reported in various proteins, the factors that lead to those modifications in proteins in vivo remain obscure. Therefore, an in vitro system is needed to assess the mechanisms of modifications of Asp under various conditions. Deamidation of Asn to Asp in proteins occurs more rapidly than isomerization/racemization of Asp, although the reaction passes through the same intermediate in both pathways. Here, therefore, we replaced Asp151 in human lens αA‐crystallin with Asn by using site‐directed mutagenesis. The recombinant protein was expressed in Escherichia coli and used to investigate the deamidation/isomerization/racemization of Asn151 after incubation at 50°C for various durations and under different pH. After incubation, the mutant αA‐crystallin was subjected to enzymatic digestion followed by liquid chromatography–MS/MS to evaluate the ratio of modifications in Asn151‐containing peptides. The Asp151Asn αA‐crystallin mutant showed rapid deamidation to Asp with the formation of specific Asp isomers. In particular, deamidation increased greatly under basic conditions. By contrast, subunit–subunit interactions between αA‐crystallin and αB‐crystallin had little effect on the modification of Asn151. Our findings suggest that the Asp151Asn αA‐crystallin mutant represents a good in vitro model protein to assess deamidation, isomerization, and the racemization intermediates. Furthermore, our in vitro results show a different trend from in vivo data, implying the presence of specific factors that induce racemization from L‐Asp to D‐Asp residues in vivo. 相似文献
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Non‐targeted Metabolomic Profile of Fagus Sylvatica L. Leaves using Liquid Chromatography with Mass Spectrometry and Gas Chromatography with Mass Spectrometry
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Estrella Cadahía Brígida Fernández de Simón Ismael Aranda Miriam Sanz David Sánchez‐Gómez Ernani Pinto 《Phytochemical analysis : PCA》2015,26(2):171-182
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Profiling of Hura crepitans L. latex by ultra‐high‐performance liquid chromatography/atmospheric pressure chemical ionisation linear ion trap Orbitrap mass spectrometry
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Manon Trinel Valérie Jullian Anne‐Cécile Le Lamer Icram Mhamdi Kember Mejia Denis Castillo Billy Joel Cabanillas Nicolas Fabre 《Phytochemical analysis : PCA》2018,29(6):627-638
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Yina Tang Tao Yi Homing Chen Zhongzhen Zhao Zhitao Liang Hubiao Chen 《Phytochemical analysis : PCA》2013,24(4):413-422
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The aspect of time is essential in biological processes and thus it is important to be able to monitor signaling molecules through time. Proteins are key players in cellular signaling and they respond to many stimuli and change their expression in many time‐dependent processes. Mass spectrometry (MS) is an important tool for studying proteins, including their posttranslational modifications and their interaction partners—both in qualitative and quantitative ways. In order to distinguish the different trends over time, proteins, modification sites, and interacting proteins must be compared between different time points, and therefore relative quantification is preferred. In this review, the progress and challenges for MS‐based analysis of time‐resolved proteome dynamics are discussed. Further, aspects on model systems, technologies, sampling frequencies, and presentation of the dynamic data are discussed. 相似文献
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Adam J. Rabalski Jon D. Williams Ryan A. McClure Anil Vasudevan Aleksandra Baranczak 《Proteomics》2019,19(11)
Chemical proteomics enables comprehensive profiling of small molecules in complex proteomes. A critical component to understand the interactome of a small molecule is the precise location on a protein where the interaction takes place. Several approaches have been developed that take advantage of bio‐orthogonal chemistry and subsequent enrichment steps to isolate peptides modified by small molecules. These methods rely on target identification at the level of mass spectrometry making it difficult to interpret an experiment when modified peptides are not identified. Herein, an approach in which fluorescence‐triggered two‐dimensional chromatography enables the isolation of small molecule‐conjugated peptides prior to mass spectrometry analysis is described. In this study, a bromocoumarin moiety has been utilized that fluoresces and generates a distinct isotopic signature to locate and identify modified peptides. Profiling of a cellular cysteinome with the use of a bromocoumarin tag demonstrates that two‐dimensional fluorescence‐based chromatography separation can enable the identification of proteins containing reactive cysteine residues. Moreover, the method facilitates the interrogation of low abundance proteins with greater depth and sensitivity than a previously reported isotope‐targeted approach. Lastly, this workflow enables the identification of small‐molecule modified peptides from a protein‐of‐interest. 相似文献
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Simultaneous quantitative determination of multiple bioactive markers in Ocimum sanctum obtained from different locations and its marketed herbal formulations using UPLC‐ESI‐MS/MS combined with principal component analysis
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Renu Pandey Preeti Chandra Mukesh Srivastava D. K. Mishra Brijesh Kumar 《Phytochemical analysis : PCA》2015,26(6):383-394