Search results for "Electrospray Ionization"
showing 10 items of 275 documents
Proteomic analysis of the acid-soluble nacre matrix of the bivalve Unio pictorum: detection of novel carbonic anhydrase and putative protease inhibit…
2010
10 pages; International audience; The matrix extracted from mollusc shell nacre is a mixture of proteins and glycoproteins that is thought to play a major role in controlling biomineral synthesis and in increasing its mechanical properties. We investigated the nacreous shell of the freshwater mussel Unio pictorum, to which we applied a proteomics approach adapted to mollusc shell proteins. On one hand, the acid-soluble nacre matrix was fractionated by SDS-PAGE and the five main protein bands (P95, P50, P29, P16, and P12) were digested with trypsin and analyzed by nanoLC-MS/MS followed by de novo sequencing. On the other hand, the acid-soluble nacre matrix was analyzed in a similar manner, w…
Tryptophan promotes morphological and physiological differentiation in Streptomyces coelicolor.
2015
The molecular mechanisms regulating tryptophan biosynthesis in actinomycetes are poorly understood; similarly, the possible roles of tryptophan in the differentiation program of microorganism life-cycle are still underexplored. To unveil the possible regulatory effect of this amino acid on gene expression, an integrated study based on quantitative teverse transcription-PCR (qRT-PCR) and proteomic approaches was performed on the actinomycete model Streptomyces coelicolor. Comparative analyses on the microorganism growth in a minimal medium with or without tryptophan supplementation showed that biosynthetic trp gene expression in S. coelicolor is not subjected to a negative regulation by the …
Surfactant self-assembly in the gas phase: Bis(2-ethylhexyl)sulfosuccinate- alkaline metal ion aggregates
2008
Molecular dynamics (MD) simulations were conducted for systems in vacuo consisting of n AOT anions (bis(2-ethylhexyl)sulfosuccinate ions) and n 1 or n Na+ ions up to n = 20. For n = 15, positively charged systems with Li+, K+, and Cs+ cations were also considered. All systems were observed to form reverse micelle-like aggregates whose centre is occupied by cations and polar heads in a very compact solid-like way, while globally the aggregate has the form of an elongated and rather flat ellipsoid. Various types of statistical analyses were carried out on the systems to enlighten structural and dynamical properties including gyration radius, atomic pair correlation functions, atomic B-factor …
New perspectives on diastereoselective determination of hexabromocyclododecane traces in fish by ultra high performance liquid chromatography-high re…
2014
a b s t r a c t A new analytical method is presented for diastereoisomer-specific identification and quantitation of hexabromocyclododecanes (HBCD) in fish samples. The method is based on extraction of the target analytes from samples with a mixture of organic solvents, with further three-stage clean-up includ- ing destructive removal of matrix components with sulphuric acid and acid-impregnated silica gel, and Florisil adsorption column chromatography. Ultra high performance liquid chromatography (UPLC) cou- pled with high resolution (HR) Orbitrap mass spectrometry featuring heated electrospray ionization (HESI-II) interface operated in negative ion mode was employed for the identification…
Chemoenzymatic Synthesis of Functional Sialyl LewisX Mimetics with a Heteroaromatic Core
2014
Functional mimetics of the sialyl Lewis(X) tetrasaccharide were prepared by the enzymatic sialylation of a 1,3-diglycosylated indole and a glycosyl azide, which was subsequently transformed into a 1,4-diglycosylated 1,2,3-triazole, by using the trans-sialidase of Trypanosoma cruzi. These compounds inhibited the binding of E-, L-, and P-selectin-coated nanoparticles to polyacrylamide-bound sialyl-Lewis(X) -containing neighboring sulfated tyrosine residues (sTyr/sLe(X) -PAA) at low or sub-millimolar concentrations. Except for E-selectin, the mimetics showed higher activities than the natural tetrasaccharide.
Levansucrases from Pseudomonas syringae pv. tomato and P. chlororaphis subsp. aurantiaca: Substrate specificity, polymerizing properties and usage of…
2011
Levansucrases of Pseudomonas syringae pv. tomato DC3000 (Lsc3) and Pseudomonas chlororaphis subsp. aurantiaca (also Pseudomonas aurantiaca) (LscA) have 73% identity of protein sequences, similar substrate specificity and kinetic properties. Both enzymes produce levan and fructooligosaccharides (FOS) of varied length from sucrose, raffinose and sugar beet molasses. A novel high-throughput chip-based nanoelectrospray mass spectrometric method was applied to screen alternative fructosyl acceptors for levansucrases. Lsc3 and LscA could both transfructosylate D-xylose, D-fucose, L- and D-arabinose, D-ribose, D-sorbitol, xylitol, xylobiose, D-mannitol, D-galacturonic acid and methyl-α-D-glucopyra…
Self-assembly and intra-cluster reactions of erbium and ytterbium bis(2-ethylhexyl)sulfosuccinates in the gas phase.
2014
RATIONALE: The study of surfactant organization in vacuum allows surfactant–surfactant interaction to be unveiled in the absence of surrounding solvent molecules. Knowledge on their chemical-physical properties may also lead to the definition of more efficient gas-phase carriers, air-cleaning agents and nanoreactors. In addition, the presence of lanthanide-group ions adds unique photochemical properties to surfactants. METHODS: The structural features, stability and fragmentation patterns of charged aggregates formed by lanthanide- functionalized surfactants, ytterbium and erbium bis(2-ethylhexyl)sulfosuccinate ((AOT) 3 Yb and (AOT) 3 Er), have been investigated by electrospray ionization m…
Entrapment of amino acids in gas phase surfactant assemblies: The case of tryptophan confined in positively charged (1R,2S)-dodecyl (2-hydroxy-1-meth…
2017
The ability of positively charged aggregates of the surfactant (1R,2S)‐dodecyl (2‐hydroxy‐1‐methyl‐2‐phenylethyl))dimethylammonium bromide (DMEB) to incorporate D-tryptophan or L-tryptophan in the gas phase has been investigated by electrospray ion mobility mass spectrometry (ESIâIMâMS). Strongly impacted by the pH of the electrosprayed solutions, both protonated (T+) and deprotonated (T-) tryptophan are effectively included into the aggregates, whereas, tryptophan in zwitterionic (T0) form is practically absent in singly charged DMEB aggregates but can be found in multiply charged ones. The ability to incorporate tryptophan increases with the aggregation number and charge state of aggr…
HPLC-DAD-ESI-MS2analytical profile of extracts obtained from purple sweet potato after green ultrasound-assisted extraction
2016
International audience; Ultrasound pre-treatment (UAE) was applied to assist the extraction of valuable compounds (polyphenols (especially anthocyanins), and proteins) from purple sweet potato (PSP). Under optimum conditions (ultrasound time (40 min); supplementary hot extraction (80 °C) up to 120 min; pH: 2.5; ethanol concentration: 58%), the highest concentrations of polyphenols (3.877 mg/g), anthocyanins (0.293 mg/g), and proteins (0.753 mg/g) were found, with minimal specific energy consumption (8406 J/mg).Moreover, anthocyanin and non-anthocyanin polyphenols in PSP extract from optimized extraction temperature were identified using HPLC-DAD-ESI-MS2. The major identified anthocyanins we…
LC–ESI–FT–MSn Metabolite Profiling of Symphytum officinale L. Roots Leads to Isolation of Comfreyn A, an Unusual Arylnaphthalene Lignan
2020
Preparations of comfrey (Symphytum officinale L.) roots are used topically to reduce inflammation. Comfrey anti-inflammatory and analgesic properties have been proven in clinical studies. However, the bioactive compounds associated with these therapeutic activities are yet to be identified. An LC&ndash