Search results for "chromatography"
showing 10 items of 5037 documents
External Influences on Invertebrate Brain Histamine and Related Compounds via an Automated Derivatization Method for Capillary Electrophoresis.
2017
8 pages; International audience; Histamine has been shown to modulate visual system and photic behavior in arthropods. However, few methods are available for the direct quantification of histamine and its precursor and metabolites in arthropod brain. In this work, a method for the separation of histamine, its precursor histidine, and its metabolite N-methyl-histamine from brain extracts of a freshwater crustacean has been developed using capillary electrophoresis with laser-induced fluorescence detection. Molecules were tagged on their primary amine function with naphthalene-2,3-dicarboxaldehyde, but derivatized histamine and N-methyl-histamine exhibited poor stability in contrast to deriva…
Direct identification of microorganisms from thioglycolate broth by MALDI-TOF MS.
2017
We developed an easy MALDI-TOF MS-based assay to identify microorganisms directly from thioglycolate broth. A total of 101 positive thioglycolate broths inoculated with 15 different kinds of samples were evaluated. In 91 samples (90.1%), direct MALDI-TOF MS identifications were the same as those obtained after conventional laboratory procedures including subcultures. In 10 samples misidentified by direct processing, yeasts or mixed cultures grew in the thioglycolate subcultures, or high cellular debris hampered a correct analysis. This rapid method can provide a fast, clinically- relevant species-level identification without disturbing the daily workflow in clinical microbiology laboratorie…
Determination of melatonin in Acyrthosiphon pisum aphids by liquid chromatography-tandem mass spectrometry.
2015
Melatonin is a hormone mainly involved in the regulation of circadian and seasonal rhythms in both invertebrates and vertebrates. Despite the identification of melatonin in many insects, its involvement in the insect seasonal response remains unclear. A liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed for melatonin analysis in aphids (Acyrthosiphon pisum) for the first time. After comparing two different procedures and five extraction solvents, a sample preparation procedure with a mixture of methanol/water (50:50) was selected for melatonin extraction. The method was validated by analyzing melatonin recovery at three spiked concentrations (5, 50 and 100 p…
MetProc: Separating Measurement Artifacts from True Metabolites in an Untargeted Metabolomics Experiment
2019
High-throughput metabolomics using liquid chromatography and mass spectrometry (LC/MS) provides a useful method to identify biomarkers of disease and explore biological systems. However, the majority of metabolic features detected from untargeted metabolomics experiments have unknown ion signatures, making it critical that data should be thoroughly quality controlled to avoid analyzing false signals. Here, we present a postalignment method relying on intermittent pooled study samples to separate genuine metabolic features from potential measurement artifacts. We apply the method to lipid metabolite data from the PREDIMED (PREvención con DIeta MEDi-terránea) study to demonstrate clear remova…
Insights into the Structure of the Vip3Aa Insecticidal Protein by Protease Digestion Analysis
2017
Vip3 proteins are secretable proteins from Bacillus thuringiensis whose mode of action is still poorly understood. In this study, the activation process for Vip3 proteins was closely examined in order to better understand the Vip3Aa protein stability and to shed light on its structure. The Vip3Aa protoxin (of 89 kDa) was treated with trypsin at concentrations from 1:100 to 120:100 (trypsin:Vip3A, w:w). If the action of trypsin was not properly neutralized, the results of SDS-PAGE analysis (as well as those with Agrotis ipsilon midgut juice) equivocally indicated that the protoxin could be completely processed. However, when the proteolytic reaction was efficiently stopped, it was revealed t…
Protein denaturation caused by heat inactivation detrimentally affects biomolecular corona formation and cellular uptake
2018
Adsorption of blood proteins to the surface of nanocarriers is known to be the critical factor influencing cellular interactions and eventually determining the successful application of nanocarriers as drug carriers in vivo. There is an increasing number of reports summarizing large data sets of all identified corona proteins. However, to date our knowledge about the multiple mechanisms mediating interactions between proteins and nanocarriers is still limited. In this study, we investigate the influence of protein structure on the adsorption process and focus on the effect of heat inactivation of serum and plasma, which is a common cell culture procedure used to inactivate the complement sy…
Cell Type-Specific Tandem Affinity Purification of the Mouse Hippocampal CB1 Receptor-Associated Proteome
2016
G protein coupled receptors (GPCRs) exert their effects through multiprotein signaling complexes. The cannabinoid receptor type 1 (CB1) is among the most abundant GPCRs in the mammalian brain and involved in a plethora of physiological functions. We used a combination of viral-mediated cell type-specific expression of a tagged CB1 fusion protein (CB1-SF), tandem affinity purification (TAP) and proteomics on hippocampal mouse tissue to analyze the composition and differences of CB1 protein complexes in glutamatergic neurons and in GABAergic interneurons. Purified proteins underwent tryptic digestion and were identified using deep-coverage data-independent acquisition with ion mobility separa…
Multicentric study of the effect of pre-analytical variables in the quality of plasma samples stored in biobanks using different complementary proteo…
2016
12 páginas, 7 figuras.-- Jesús Mateos ... et al.
Self-packed core shell nano liquid chromatography columns and silica-based monolithic trap columns for targeted proteomics.
2016
Self-preparation of nano liquid chromatography (nLC) columns has advantages regarding cost and flexibility. For targeted proteomics, we evaluated several approaches for particle-packing nLC columns and manufacturing fritless silica-based monolithic trap columns (50μm inner diameter). Our preferred approach for nLC column preparation was to magnetically stir Accucore core shell particles (C18 stationary phase) in ACN/water (80/20, v/v) suspensions during pressure-driven filling of polymer-fritted standard fused silica capillaries. The columns were ready for use about one hour after preparation had begun. They had comparable peak capacities (peptides) to commercial columns, and satisfactory w…
Orange proteomic fingerprinting: From fruit to commercial juices.
2015
Combinatorial peptide ligand library technology, coupled to mass spectrometry, has been applied to extensively map the proteome of orange pulp and peel and, via this fingerprinting, to detect its presence in commercial orange juices and drinks. The native and denaturing extraction protocols have captured 1109 orange proteins, as identified by LC-MS/MS. This proteomic map has been searched in an orange concentrate, from a Spanish juice manufacturer, as well as in commercial orange juices and soft drinks. The presence of numerous orange proteins in commercial juices has demonstrated the genuineness of these products, prepared by using orange fruits as original ingredients. However, the low nu…