Sommaire Le couplage d'une chromatographie avec écoulement continu du solvant Pyridine/éthanol/eau (442) et d'une électrophorèse en milieu alcalin (Borax 0,025 M.) sur couche mince de poudre de cellulose permet de séparer parfaitement les aminoacides ayant une faible mobilité en chromatographie de partage. Si des couches minces de taille 20×40 cm et une révélation des aminoacides par l'acide trinitrobenzène sulfonique sont utilisées, d'excellents chromato-électrogrammes sont obtenus. Ce procédé permet d'obtenir d'excellentes séparations entre amino-acides et peptides, s'il est appliqué sans écoulement continu du solvant chromatographique.
Chromato-electrophoresis of amino acids on a thin layer of cellulose powder Part 6 improvement of a procedure with high separation efficiency for neutral aminoacids with little mobility in partition chromatography
Summary A combination of chromatography with continuous flow of the eluant pyridine/ethanol/water (442) and electrophoresis in alkaline medium (Borax 0.025 M) on a thin layer of cellulose powder provides for perfect separation of amino acids with little mobility in partition chromatography. When thin layers of 20×40 cm size and development of the amino acids by trinitrobenzene-sulfonic acid are used, excellent chromato-electrograms can be obtained. This procedure will give excellent separations between amino acids and peptides if it is used without continuous flow of the chromatographic solvent.
Chromato-Elektrophorese von Aminosäuren auf einer Cellulosepulver-Dünnschicht 6. Teil: Verbesserung eines Verfahrens mit hoher Trennleistung für die neutralen Aminosäuren mit geringer Mobilität in der Verteilungs-Chromatographie
Zusammenfassung Durch Kombination von Chromatographie mit kontinuierlichem Durchsatz des Flißmittels Pyridin/Äthanol/Wasser (442) und Elektrophorese in alkalischem Medium (Borax 0,025 M) auf einer Cellulosepulver-Dünnschicht lassen sich die Aminosäuren mit schwacher Mobilität in der Verteilungschromatographie gut trennen. Wenn Dünschichten von 20×40 cm und Entwicklung der Aminosäuren durch Trinitrobenzolsulfonsäure verwendet werden, erhält man ausgezeichnete Chromato-Elektrogramme. Mit diesem Verfahren lassen sich ausgezeichnete Trennungen von Aminosäuren und Peptiden erzielen, wenn es ohne kontinuierlichen Durchsatz des chromatographischen Fließmittels angewandt wird.
Résumé Des associations d'électrophorèse et de chromatographie dans des milieux acides sur couche mince de cellulose à fibres courtes sont étudiées: acide formique 1 M.—tertbutanol ou tert-pentanol/éthanol/acide formique/eau (40:38:2:20, v/v) ou propanol/éthianol/acid formique/eau (35:35:5:20). Les relations existant entre le pouvoir séparateur et les constituants (alcools) des solvants ou les équilibres ioniques en chromatographie sont examinés. On discute des problèmes relatifs à l'optimisation des méthodes et des différences de pouvoir séparateur existant entre les nouveau procédés et les procédés antérieurement décrits.
Coupling of electrophoresis and chromatography on amorphous cellulose thin layers for the separation of amino acids. Influence of ionic equilibria and solvent components on chromatographic separations with alcohols/acid/water solvents
Summary Associations of electrophoresis and chromatography in acidic media on thin layers of cellulose with short fibres, are studied: 1 mol. dm–3 formic acid-tert. butanol or tert, pentanol/ethiano/formic acid/water (40:38:2:20, v/v) or propanol/ethano/formic acid/water 935:35:5: 20). The relationship between separation power and solvent components (alcohols) or ionic equilibria in chromatography is examined. Optimization of emthods and origins of differences in separation power between niew and previously described procedures are discussed
The combination of electron paramagnetic resonance (EPR) and mass spectrometry (MS) was used as an efficient tool to elucidate the mechanism of an ene-reaction between a dienol compound and 2-methyl-2-nitrosopropane. 相似文献
An intramolecular 6π/10π-electrocyclization from ketene-iminium salts was developed for the preparation of naphthylamines. Various substituents on the nitrogen, on the aromatic ring, and on the olefin were studied. Tricyclic skeletons were obtained in few steps and good overall yields. The electrocyclization of ketene-iminium salts has been computationally explored by means of DFT calculations and their activation barriers were compared to the parent triene as well as the corresponding dienyl allenes and dienyl ketenes. Electrocyclizations for ketene-iminium salts were shown to be highly exergonic and have much smaller barriers to activation. 相似文献
To study diffractive photon production at HERA, we compute the projection of the impact-factor on the BFKL leading-order eigenfunctions for non-zero transfer. This calculation supplements former ones performed for n = 0. We provide an expression for and check that all the other components are zero.
Received: 6 September 1999 / Revised version: 21 November 1999 / Published online: 17 March 2000 相似文献
Laying the groundwork : The interfacial self‐assembly properties of an amyloid peptide were used to develop crystalline nanostructures at air–water interfaces, which were studied by both AFM microscopy and X‐ray diffraction (see image). These structures generate regular arrays of functional groups and pave the way to controlled deposition of inorganic materials like that observed in biomineralization.
The complex structure of the marine metabolic diazonamide A comprises a dichlorinated indole bis-oxazole heteroaromatic fragment, and a [b]-fused dihydrobenzofuran-dihydroindole unit containing an animal carbon, all incorporated within a strained double macrocyclic array. This review details the synthetic studies on this fascinating natural product starting from early studies on the original structure (1991-2001), through the synthesis of the originally proposed structure and the subsequent structural revision, to the eventual successful syntheses of the natural product itself. Throughout we focus on the innovative ways in which synthetic chemists have approached the challenges posed by this natural product. 相似文献
Résumé On a étudié la réaction de divers chlorures d'amines aliphatiques [-chloroéthyldiisopropylamine, N-(-chloroéthyl)-pipéridine, N--chloro-éthylpyrrolidine, -chloroéthyl-diméthylamine] avec l'alcali-cellulose. Grâce à l'étude détaillée des courbes de neutralisation des celluloses basiques obtenues et de la triméthylaminoéthyl cellulose (TMAE-cellulose), on a pu mettre en évidence les différences de réactivité des chlorures d'amine pour la formation de liaisons éther avec la cellulose et pour la quaternisation des groupes amine. Dans le cas de la -chloroéthyldi-isopropylamine et de la N-(-chloroéthyl)-pipéridine, on obtient des celluloses à groupes amine tertiaire: respectivement, la di-isopropylamino-éthylcellulose (DIPAE-cellulose) et la Pipéridine-N-éthyl-cellulose (Pipé-NE-cellulose). Dans le cas de la N-(-chloroéthyl)-pyrrolidine, la cellulose basique obtenue a une courbe de neutralisation qui correspond à un échangeur d'ions ayant des groupes amine tertiaire et des groupes ammonium quaternaire. Il en est de même dans le cas du produit de réaction de l'alcali-cellulose avec la -chloroéthyldiméthylamine (cellulose modifiée de capacité supérieure à 0,3 m.équiv./g.).Les propriétés chromatographiques de ces nouveaux échangeurs d'anions hydrophiles ont été étudiées; certains d' entre eux donnent des résultants très intérensants, spécialement, dans le domaine de la chromatographie des protéines. Pour la chromatographie des protéines la Pipéridine-N-éthyl-cellulose qui a une structure fibreuse compacte a un pouvoir séparateur aussi élevé que celui obtenu avec la DEAE-cellulose à structure fibres gélifiées réticulées.
New hydrophilic ion-exchangers for chromatography of proteins: Piperidine N-ethylcellulose and di-isopropylaminoethyl cellulose
Summary Reaction of different aliphatic amine chlorides [-chloroethyldiisopropylamine, N-(-chloroethyl)-piperidine, N (-chloroethylpyrrolidine, -chloroethyldimethylamine) with alkalicellulose has been investigated. Detailed investigation of titration curves of the basic cellulose thus obtained and of trimethylaminoethylcellulose (TMAE-cellulose) has shown that the reactivity of various amine chlorides varies in the case of formation of ether bonds with cellulose as well as in the case of quaternization of amino-groups. With -chlorethyldiisopropylamine and N-(-chloroethyl-)piperidine, celluloses with tertiary amino-groups were obtained, namely, di-isopropylamino ethyl cellulose (DIPAE-cellulose) and piperidine-N-ethyl-cellulose (Pipe-NE-cellulose). Basic cellulose obtained with N-(-chloroethyl)-pyrrolidine gives a titration curve corresponding to an ion exchanger carrying tertiary amino and quaternary ammonium groups. The same is true for the reaction product of -chloroethyl-dimethylamine with alkali-cellulose (modified cellulose with an exchange capacity greater than 0.3 m.equiv g–1). Chromatographic behaviour of these new hydrophilic anion exchangers has been investigated. Some of them give very interesting results, mainly in the chromatography of proteins; thus, piperidine-N-ethylcellulose with a dense fibrous texture, has a separating power as great as that of DEAE cellulose with fibres of crosslinked gel type.
Biodegradable cationic nanoparticles (cNP) made of poly(lactide) (PLA) have been shown to be promising carrier systems for in vivo DNA delivery and immunization. In previous work, we have described a versatile approach for the elaboration of cationic PLA cNP based on the use of pre-formed particles and subsequent adsorption of a model polycation, the poly(ethylenimine) (PEI). Here, we evaluated two more polycations, chitosan and poly(2-dimethyl-amino)ethyl methacrylate (pDMAEMA)) to determine the most suitable one for the development of PLA cNP as DNA carriers. Cationic PLA-PEI, PLA-chitosan and PLA-pDMAEMA nanoparticles were compared for interaction with plasmid DNA and, more importantly, with regards to the biological properties of bound DNA. pDMAEMA coating yielded the most positively charged nanoparticles with the highest DNA binding capacity (32 mg/g). Loaded with DNA, all three cNP were in the same size range ( approximately 500 nm) and had a negative zeta potential (-50 mV). PLA-chitosan was the only cNP that released DNA at pH 7; the two others required higher pH. Adsorption and release from cNP did not alter structural and functional integrity of plasmid DNA. Moreover, DNA coated onto cNP was partially protected from nuclease degradation, although this protection was less efficient for PLA-chitosan than others. The highest transfection efficiency in cell culture was obtained with PLA-pDMAEMA carriers. We have shown that at least three different cationic polymers (chitosan, PEI, pDMAEMA) can be used for the production of PLA-based particulate DNA carriers and most probably other cationic polymers can also be used in the same purpose. PLA-pDMAEMA cNP were the most promising system for DNA delivery in this in vitro study. Our future work will focus on the in vivo evaluation of these gene delivery systems. 相似文献
