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21.
Laurence Muhr Steve Pontvianne Katalin Selmeczi Cdric Paris Sandrine Boschi‐Muller Laetitia Canabady‐Rochelle 《Journal of separation science》2020,43(11):2031-2041
Some metal‐chelating peptides have antioxidant properties, with potential nutrition, health, and cosmetics applications. This study aimed to simulate their separation on immobilized metal ion affinity chromatography from their affinity constant for immobilized metal ion determined in surface plasmon resonance, both technics are based on peptide‐metal ion interactions. In our approach, first, the affinity constant of synthetic peptides was determined by surface plasmon resonance and used as input data to numerically simulate the chromatographic separation with a transport‐dispersive model based on Langmuir adsorption isotherm. Then, chromatographic separation was applied on the same peptides to determine their retention time and compare this experimental tR with the simulated tR obtained from simulation from surface plasmon resonance data. For the investigated peptides, the relative values of tR were comparable. Hence, our study demonstrated the pertinence of such numerical simulation correlating immobilized metal ion affinity chromatography and surface plasmon resonance. 相似文献
22.
Sandrine PerocheHélène Parrot-Lopez 《Tetrahedron letters》2003,44(2):241-245
A new series of fluorinated amphiphilic β-cyclodextrin derivatives has been synthesized. The strategy is based on the modification of the C-6 position of the mono-6-deoxy-6A-para-tolylsulfonyl, di-6A, 6D-deoxy-6A, 6D-(para-tolylsulfonyl) and heptakis-(6-deoxy-6-iodo)-β-cyclodextrin precursors. The synthesis lead to mono-perfluoroalkylthio-, di-perfluoroalkylthio- and heptakis-perfluoroalkylthio-β-cyclodextrin in excellent yields (90-99%). 相似文献
23.
Sandrine LangleFranck David-Quillot Mohamed AbarbriAlain Duchêne 《Tetrahedron letters》2003,44(8):1647-1649
Using double Stille cross-coupling reaction bromo (or chloro)benzylbromide is easily transformed into substituted styrene monomers bearing a wide range of substituents in para position 相似文献
24.
Using a double Suzuki cross-coupling reaction ortho- or para-bromobenzyl bromides are easily transformed into unsymmetrical diaryl (or heteroaryl) methanes 相似文献
25.
Sandrine Bourgoin-Voillard Carlos Afonso Denis Lesage Emilie-Laure Zins Jean-Claude Tabet P. B. Armentrout 《Journal of the American Society for Mass Spectrometry》2013,24(3):365-380
The kinetic method is a widely used approach for the determination of thermochemical data such as proton affinities (PA) and gas-phase acidities (ΔH° acid ). These data are easily obtained from decompositions of noncovalent heterodimers if care is taken in the choice of the method, references used, and experimental conditions. Previously, several papers have focused on theoretical considerations concerning the nature of the references. Few investigations have been devoted to conditions required to validate the quality of the experimental results. In the present work, we are interested in rationalizing the origin of nonlinear effects that can be obtained with the kinetic method. It is shown that such deviations result from intrinsic properties of the systems investigated but can also be enhanced by artifacts resulting from experimental issues. Overall, it is shown that orthogonal distance regression (ODR) analysis of kinetic method data provides the optimum way of acquiring accurate thermodynamic information. 相似文献
26.
Monique?SabatyEmail author Sandrine?Grosse Geraldine?Adryanczyk Séverine?Boiry Frédéric?Biaso Pascal?Arnoux David?Pignol 《BMC biochemistry》2013,14(1):28
Background
YedY, a molybdoenzyme belonging to the sulfite oxidase family, is found in most Gram-negative bacteria. It contains a twin-arginine signal sequence that is cleaved after its translocation into the periplasm. Despite a weak reductase activity with substrates such as dimethyl sulfoxide or trimethylamine N-oxide, its natural substrate and its role in the cell remain unknown. Although sequence conservation of the YedY family displays a strictly conserved hydrophobic C-terminal residue, all known studies on Escherichia coli YedY have been performed with an enzyme containing a 6 histidine-tag at the C-terminus which could hamper enzyme activity.Results
In this study, we demonstrate that the tag fused to the C-terminus of Rhodobacter sphaeroides YedY is detrimental to the enzyme’s reductase activity and results in an eight-fold decrease in catalytic efficiency. Nonetheless this C-terminal tag does not influence the properties of the molybdenum active site, as assayed by EPR spectroscopy. When a cleavable His-tag was fused to the N-terminus of the mature enzyme in the absence of the signal sequence, YedY was expressed and folded with its cofactor. However, when the signal sequence was added upstream of the N-ter tag, the amount of enzyme produced was approximately ten-fold higher.Conclusion
Our study thus underscores the risk of using a C-terminus tagged enzyme while studying YedY, and presents an alternative strategy to express signal sequence-containing enzymes with an N-terminal tag. It brings new insights into molybdoenzyme maturation in R. sphaeroides showing that for some enzymes, maturation can occur in the absence of the signal sequence but that its presence is required for high expression of active enzyme.27.
Pierre-Olivier Bussière Jérémy Peyroux Geneviève Chadeyron Sandrine Therias 《Polymer Degradation and Stability》2013
The photochemical behaviour of polymer–nanoparticles/nanocomposites has been studied depending on the geometry of the nanofiller and an overview of the studies reported in the last decade is tentatively given. Depending on their functionality, nanoparticles can impact the durability of the nanocomposite materials under light irradiation. The behaviour to UV-light exposure in presence of oxygen of various types of nanocomposites with clays, LDH and carbon nanotubes has been investigated and recent progress on the influence of functional nanoparticles on the polymer photodegradation is reported. The influence of photocatalytic (ZnO and TiO2) nanoparticles and phosphors on the photooxidation of the polymeric matrix and the durability of the material properties are characterized. From a general point of view, the stabilization strategy of polymer nanocomposites must be adapted depending on the nanofiller. 相似文献
28.
An improved capillary electrophoresis method for in vitro monitoring of the challenging early steps of Aβ1–42 peptide oligomerization: Application to anti‐Alzheimer's drug discovery 下载免费PDF全文
Dimitri Brinet Julia Kaffy Farid Oukacine Sarah Glumm Sandrine Ongeri Myriam Taverna 《Electrophoresis》2014,35(23):3302-3309
We report an improved CE method to monitor in vitro the self‐assembly of monomeric amyloid β‐peptide (42 amino acids amyloid β‐peptide, Aβ1–42) and in particular the crucial early steps involved in the formation of the neurotoxic oligomers. In order to start the kinetics from the beginning, sample preparation was optimized to provide samples containing exclusively the monomeric form. The CE method was also improved using a dynamic coating and by reducing the separation distance. Using this method, the disappearance of the monomer as well as the progressive formation of four species during the self‐assembly process can now be monitored and quantified over time. The hydrodynamic radius of the species present at the initial kinetics step was estimated around 1.8 nm by Taylor dispersion analysis while SDS‐PAGE analyses showed the predominance of the monomer. These results confirmed that the Aβ1–42 species present at this initial time was the monomer. Methylene blue, an anti‐Alzheimer disease candidate, was then evaluated. In spite of an oligomerization inhibition, the enhanced disappearance of the Aβ1–42 monomer provoked by methylene blue was demonstrated for the first time. This method, allowing the monomeric and smallest oligomeric species to be monitored, represents a new accurate and precise way to evaluate compounds for drug discovery. 相似文献
29.
Abdelhouad Oukhrib Laurence Bonnafoux Armen Panossian Sandrine Waifang Duc Hanh Nguyen Martine Urrutigoity Françoise Colobert Maryse Gouygou Frédéric R. Leroux 《Tetrahedron》2014
A new family of non-symmetrical disubstituted dibenzophospholes possessing different steric and electronic effects have been synthesized and characterized. Their preliminary evaluation in rhodium-catalyzed hydroformylation reactions is presented. 相似文献
30.
Ming Xu Sandrine Frelon Olivier Simon Ryszard Lobinski Sandra Mounicou 《Analytical and bioanalytical chemistry》2014,406(4):1063-1072
A non-denaturating isoelectric focusing (ND-IEF) gel electrophoresis protocol has been developed to study and identify uranium (U)–protein complexes with laser ablation–inductively coupled plasma mass spectrometry (LA-ICP MS) and electrospray ionization mass spectrometry (ESI-MS). The ND-IEF-LA-ICP MS methodology set-up was initiated using in vitro U–protein complex standards (i.e., U–bovine serum albumin and U–transferrin) allowing the assessment of U recovery to 64.4?±?0.4 %. This methodology enabled the quantification of U–protein complexes at 9.03?±?0.23, 15.27?±?0.36, and 177.31?±?25.51 nmol U L?1 in digestive gland cytosols of the crayfish, Procambarus clarkii, exposed respectively to 0, 0.12, and 2.5 μmol of waterborne depleted U L?1 during 10 days. ND-IEF-LA-ICP MS limit of detection was 19.3 pmol U L?1. Elemental ICP MS signals obtained both in ND-IEF electropherograms and in size exclusion chromatograms of in vivo U–protein complexes revealed interactions between U- and Fe- and Cu-proteins. Moreover, three proteins (hemocyanin, pseudohemocyanin-2, and arginine kinase) out of 42 were identified as potential uranium targets in waterborne-exposed crayfish cytosols by microbore reversed phase chromatography coupled to molecular mass spectrometry (µRPC-ESI-MS/MS) after ND-IEF separation. Figure
The paper presents the development of a non-denaturating protocol for the separation of uranium-protein complexes by isoelectric focusing gel electrophoresis (ND-IEF) before their quantitative detection by Laser Ablation coupled to Inductively Coupled Plasma Mass Spectrometry. Potential protein targets of uranium are subsequently identified by liquid chromatography - electrospray mass spectrometry 相似文献