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1.
Francis Canon Franck Paté Emmanuelle Meudec Thérèse Marlin Véronique Cheynier Alexandre Giuliani Pascale Sarni-Manchado 《Analytical and bioanalytical chemistry》2009,395(8):2535-2545
Numerous protein–polyphenol interactions occur in biological and food domains particularly involving proline-rich proteins,
which are representative of the intrinsically unstructured protein group (IUP). Noncovalent protein–ligand complexes are readily
detected by electrospray ionization mass spectrometry (ESI-MS), which also gives access to ligand binding stoichiometry. Surprisingly,
the study of interactions between polyphenolic molecules and proteins is still an area where ESI-MS has poorly benefited,
whereas it has been extensively applied to the detection of noncovalent complexes. Electrospray ionization mass spectrometry
has been applied to the detection and the characterization of the complexes formed between tannins and a human salivary proline-rich
protein (PRP), namely IB5. The study of the complex stability was achieved by low-energy collision-induced dissociation (CID)
measurements, which are commonly implemented using triple quadrupole, hybrid quadrupole time-of-flight, or ion trap instruments.
Complexes composed of IB5 bound to a model polyphenol EgCG have been detected by ESI-MS and further analyzed by MS/MS. Mild
ESI interface conditions allowed us to observe intact noncovalent PRP–tannin complexes with stoichiometries ranging from 1:1
to 1:5. Thus, ESI-MS shows its efficiency for (1) the study of PRP–tannin interactions, (2) the determination of stoichiometry,
and (3) the study of complex stability. We were able to establish unambiguously both their stoichiometries and their overall
subunit architecture via tandem mass spectrometry and solution disruption experiments. Our results prove that IB5·EgCG complexes
are maintained intact in the gas phase.
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2.
Pyochelin is a siderophore and virulence factor common to Burkholderia cepacia and several Pseudomonas strains. It is isolated from bacterial media as a mixture of two epimers, which readily equilibrate in most solvents. Experiments based on high-performance liquid chromatography/electrospray ionization mass spectrometry are reported here, allowing the investigation of the different Fe(III)-chelating properties of pyochelin diastereomers in solution without the need for labourious isolation. It is demonstrated in this study that only one of the two pyochelin diastereomers is able to chelate Fe(III); no Fe(III) complexes of the other diastereomer could be detected. The Fe(III)–pyochelin complex exhibited a 1:1 metal-to-siderophore ratio and no evidence for other stoichiometries was found.
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3.
Blo G Ceccarini A Conato C Contado C Fagioli F Fuoco R Pagnoni A Dondi F 《Analytical and bioanalytical chemistry》2006,384(4):922-930
Direct hyphenation of electrothermal atomic-absorption spectroscopy (ETAAS) to sedimentation field-flow fractionation (SdFFF)
has been developed to enable elemental characterization of submicron particles as a function of size. This hyphenation is
particularly suitable for characterizing colloidal particles of environmental interest, for example water-borne particles.
The interface is an automatic capillary injection device (CID) which enables direct introduction of large and variable volumes
of colloidal particle suspensions into a hot graphite furnace, thus preconcentrating the colloidal particles on the furnace
walls. The method was validated by determination of Fe in certified submicron Fe2O3. The procedure was set up by first optimizing the SdFFF fractionation under programmed field conditions, thus enabling optimum
fractionation of particle size. The ETAAS procedure was then tested to determine whether it could be used for direct analysis
of Fe2O3 slurries without the need for a mineralization step. CID coupled to ETAAS was subsequently exploited for its ability to enhance
the sensitivity, because of the increased injection volume. Statistical tests and data handling were conducted to prove the
suitability of the ETAAS-CID module. Finally, off-line and on-line ETAAS-CID-SdFFF hyphenation were investigated. These experiments
emphasized the advantages of the on-line coupling, because it enables synchronized sampling, enrichment, and elemental analysis
of the flowing eluate. The benefits of the proposed hyphenation are the high specificity of analytical detection, increased
sensitivity, reduction of analysis time, and minimum sample handling and contamination.
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4.
Pérez Pavón JL García Pinto C Guerrero Peña A Moreno Cordero B 《Analytical and bioanalytical chemistry》2008,391(2):599-607
In the present work we report the results obtained with a methodology based on direct coupling of a headspace generator to
a mass spectrometer for the identification of different types of petroleum crudes in polluted soils. With no prior treatment,
the samples are subjected to the headspace generation process and the volatiles generated are introduced directly into the
mass spectrometer, thereby obtaining a fingerprint of volatiles in the sample analysed. The mass spectrum corresponding to
the mass/charge ratios (m/z) contains the information related to the composition of the headspace and is used as the analytical signal for the characterization
of the samples. The signals obtained for the different samples were treated by chemometric techniques to obtain the desired
information. The main advantage of the proposed methodology is that no prior chromatographic separation and no sample manipulation
are required. The method is rapid, simple and, in view of the results, highly promising for the implementation of a new approach
for oil spill identification in soils.
Figure PCA score plots illustrate clear discrimination of types of crude oil in polluted soil samples (e.g. results are shown for
vertisol) 相似文献
5.
We have developed an iterative procedure for predicting the retention times of polycyclic aromatic hydrocarbons (PAHs) and
n-alkanes during separations by temperature-programmed gas chromatography. The procedure is based on estimates of two thermodynamic
properties for each analyte (the differences in enthalpy and entropy associated with movements between the stationary and
mobile phases) derived from data acquired experimentally in separations under isothermal conditions at temperatures spanning
the range covered by the temperature programs in ten-degree increments. The columns used for this purpose were capillary columns
containing polydimethylsiloxane-based stationary phases with three degrees of phenyl substitution (0%, 5%, and 50%). Predicted
values were mostly within 1% of experimentally determined values, implying that the method is stable and precise.
Figure Predicted values were mostly within 1 % of experimentally determined values, thus implying that the method is stable and precise 相似文献
6.
Magnetic Fe3O4-C18 composite nanoparticles of approximately 5–10 nm in size were synthesized and characterized by IR spectroscopy, atomic
absorption spectroscopy, X-ray diffraction, and transmission electron microscopy. The magnetic Fe3O4-C18 composite nanoparticles were applied for cleanup and enrichment of organophosphorous pesticides. Comparative studies
were carried out between magnetic Fe3O4-C18 composite nanoparticles and common C18 materials. Residues of organophosphorous pesticides were determined by gas chromatography
in combination with a nitrogen/phosphorus detector. The cleanup and enrichment properties of magnetic Fe3O4-C18 composite nanoparticles are comparable with those of common C18 materials for enrichment of organophosphorous pesticides,
but the cleanup and enrichment are faster and easier to perform.
Figure Presumed mechanism for the adhesion of the OPs to the Fe3O4-C18 magnetic nanoparticles 相似文献
7.
Herschbach H Hosomizu K Hahn U Leize E Van Dorsselaer A Imahori H Nierengarten JF 《Analytical and bioanalytical chemistry》2006,386(1):46-51
The electrospray mass spectrometric characterization of neutral dendrons with a carboxylic acid function or a t-butyl ester moiety at the central point and up to eight peripheral C60 subunits has been performed and is described in detail. Molecules bearing a carboxylic acid group at the center turned out
to be preferentially ionized by deprotonation, whereas those with a t-butyl ester head group were ionized by reduction of the C60 units in the infusion capillary of the electrospray source.
Electronic supplementary material Supplementary material is available for this article at and is accessible for authorized users. 相似文献
8.
Yan Xiong Jing Xu Jian-Wei Wang Ya-Feng Guan 《Analytical and bioanalytical chemistry》2009,394(3):919-923
We have prepared a novel fiber-optic evanescent wave sensor (FEWS) for dissolved oxygen (DO) detection. The sensor fabrication
was based on coating a decladded portion of an optical fiber with a microporous coating, which was prepared from 3,3,3-trifluoropropyltrimethoxysilane
and n-propyltrimethoxysilane. The fluorophores were immobilized in the porous coating and excited by the evanescent wave field
produced on the core surface of the optical fiber. The sensitivity of the sensor was quantified by the ratio of the fluorescence
intensities in pure deoxygenated (I
0) and in pure oxygenated environments (I). Results show that the quenching response of DO is increased with the enhancement of the coating surface hydrophobicity
using the presented hybrid fluorinated ORMOSILs. The calibration curve of I
0/I to [O2] is linear from 0 to 40 ppm and the detection limit is 0.05 ppm (3σ) with a short response time of 15 s for DO detection.
Figure 相似文献
9.
10.
Webb A 《Analytical and bioanalytical chemistry》2007,388(3):525-528
Figure Schematic diagram of a typical arrangement used for hyphenating chemical microseparations (e.g. capillary HPLC, CE, or CEC)
with microcoil NMR detection 相似文献
11.
Ortner K Sivanandam VN Buchberger W Müller N 《Analytical and bioanalytical chemistry》2007,388(1):173-177
Enzymatically cleaved glycans from sub-milligram quantities of erythropoietin (EPO) and ovalbumin have been analyzed, without
further purification, by two-dimensional diffusion-ordered nuclear magnetic resonance spectroscopy. At NMR sample concentrations
below 50 μmol L−1 the major components of the oligosaccharide fractions could be distinguished by their anomeric proton chemical shift and
their size-dependent diffusion coefficients.
Figure
1H NMR diffusion decay curves of anomeric protons in the EPO glycan fraction 相似文献
12.
The integration of a range of technologies including microfluidics, surface-enhanced Raman scattering and confocal microspectroscopy
has been successfully used to characterize in situ single living CHO (Chinese hamster ovary) cells with a high degree of spatial (in three dimensions) and temporal (1 s per spectrum) resolution. Following the introduction of a continuous flow of ionomycin, the real time spectral response
from the cell was monitored during the agonist-evoked Ca2+ flux process. The methodology described has the potential to be used for the study of the cellular dynamics of a range of
signalling processes.
Figure Spectral mapping of a single CHO cell 相似文献
13.
14.
The detection and identification of dilute bacterial samples by surface-enhanced Raman spectroscopy has been explored by mixing
aqueous suspensions of bacteria with a suspension of nanocolloidal silver particles. An estimate of the detection limit of
E. coli was obtained by varying the concentration of bacteria. By correcting the Raman spectra for the broad librational OH band
of water, reproducible spectra were obtained for E. coli concentrations as low as approximately 103 cfu/mL. To aid in the assignment of Raman bands, spectra for E. coli in D2O are also reported.
Figure Light scattering apparatus used to detect bacteria 相似文献
15.
Pisonero J Kroslakova I Günther D Latkoczy C 《Analytical and bioanalytical chemistry》2006,386(1):12-20
The spatial distribution and concentration of impurities in metallurgical-grade silicon (MG-Si) samples (97–99% w/w Si) were investigated by use of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The spatial resolution
(120 μm) and low limits of detection (mg kg−1) for quality assurance of such materials were studied in detail. The volume-dependent precision and accuracy of non-matrix-matched
calibration for quantification of minor elements, using NIST SRM 610 (silicate standard), indicates that LA-ICP-MS is well
suited to rapid process control of such materials. Quantitative results from LA-ICP-MS were compared with previously reported
literature data obtained by use of ICP-OES and rf-GD-OES. In particular, the distribution of element impurities and their
relationship to their different segregation coefficients in silicon is demonstrated.
Dedicated to Professor Klaus G. Heumann 相似文献
16.
Gurcel C Vercoutter-Edouart AS Fonbonne C Mortuaire M Salvador A Michalski JC Lemoine J 《Analytical and bioanalytical chemistry》2008,390(8):2089-2097
The O-linked β-N-acetylglucosamine (O-GlcNAc) modification is an abundant post-translational modification in eukaryotic cells. This dynamic glycosylation plays
a fundamental role in the activity of many nuclear and cytoplasmic proteins and is associated with pathologies like type II
diabetes, Alzheimer’s disease or some cancers. However the exact link between O-GlcNAc-modified proteins and their function in cells is largely undefined for most cases. Here we report a strategy based
on the 1,3-dipolar cycloaddition, called click chemistry, between unnatural N-acetylglucosamine (GlcNAc) analogues (substituted with an azido or alkyne group) and the corresponding biotinylated probe
to specifically detect, enrich and identify O-GlcNAc-modified proteins. This bio-orthogonal conjugation confirms that only azido analogue of GlcNAc is metabolized by the
cell. Thanks to the biotin probe, affinity purification on streptavidin beads allowed us to identify 32 O-GlcNAc-azido-tagged proteins by LC-MS/MS analysis in an MCF-7 cellular model, 14 of which were previously unreported. This
work illustrates the use of the click-chemistry-based strategy combined with a proteomic approach to get further insight into
the pattern of O-GlcNAc-modified proteins and the biological significance of this post-translational modification.
Figure Detection of biotinylated O-GlcNAz proteins in MCF-7 cells
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Caroline Gurcel and Anne-Sophie Vercoutter-Edouart contributed equally to this work. 相似文献
17.
Klejdus B Vacek J Benesová L Kopecký J Lapcík O Kubán V 《Analytical and bioanalytical chemistry》2007,389(7-8):2277-2285
A rapid-resolution HPLC/UV-VIS DAD separation method (which takes <1 min) for the determination and identification of genistin,
genistein, daidzein, daidzin, glycitin, glycitein, ononin, formononetin, sissotrin and biochanin A in fmol quantities in submicroliter
sample volumes was optimized. A linear gradient elution (0 min 22% B, 1.0 min 80% B, 1.4 min 100% B, 1.8 min 22% B) using
a mobile phase containing 0.2 % (v/v) acetic acid (solvent A) and methanol (solvent B) was applied on a Zorbax SB C18 column (1.8 μm particle size) at 80 °C. The method was verified using samples of bits of soy and methanolic extracts from
Trifolium pratense, Iresine herbstii and Ononis spinosa plants. Pseudobaptigenin glucoside, irilone, prunetin, texasin, tlatlancuayin and other isoflavones, in addition to aglycones
of isoflavones and their β-glucosides and malonyl and acetyl derivatives, were identified by UV-VIS DAD and electrospray mass
spectrometric (ESI-MS) detection in the extracts.
Figure Rapid resolution HPLC for determination and identification of isoflavones in soy preparations and plant extracts 相似文献
18.
The solubility of 1,4-naphthoquinone, plumbagin, lawsone, and juglone in supercritical carbon dioxide was determined spectroscopically at 40°C, and in the pressure range 8–18 MPa. Their solubilities at 12 MPa were between 0.3 and 10 g L−1. Plumbagin from Plumbago scandens L. roots was extracted at 40°C and 20 MPa. The extracted plumbagin mass fraction was up to 0.2% in fresh roots but down to about 0.006% in aged roots. n-Hexane and chloroform extraction of such aged roots indicates that the older and dryer the roots are, the stronger they bind plumbagin. Reversed-phase HPLC indicated a relatively pure plumbagin extract with supercritical carbon dioxide.
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19.
20.
A new kind of magnetic dextran microsphere (MDMS) with uniform shape and narrow diameter distribution has been prepared from
magnetic iron nanoparticles and dextran. Horseradish peroxidase (HRP) was successfully immobilized on the surface of an MDMS-modified
glassy-carbon electrode (GCE), and the immobilized HRP displayed excellent electrocatalytic activity in the reduction of H2O2 in the presence of the mediator hydroquinone (HQ). The effects of experimental variables such as the concentration of HQ,
solution pH, and the working potential were investigated for optimum analytical performance. This biosensor had a fast response
to H2O2 of less than 10 s and an excellent linear relationship was obtained in the concentration range 0.20 μmol L−1–0.68 mmol L−1, with a detection limit of 0.078 μmol L−1 (S/N = 3) under the optimum conditions. The response showed Michaelis–Menten behavior at larger H2O2 concentrations, and the apparent Michaelis–Menten constant was estimated to be 1.38 mmol L−1. Moreover, the selectivity, stability, and reproducibility of the biosensor were evaluated, with satisfactory results.
Figure Amperometric response of the biosensor to successive additions of H2O2 and the plot of amperometric response vs. H2O2 concentration 相似文献