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  • 1
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Cell and Developmental Biology 18 (2002), S. 289-314 
    ISSN: 1081-0706
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract Membrane fusion is a fundamental biochemical reaction and the final step in all vesicular trafficking events. It is crucial for the transfer of proteins and lipids between different compartments and for exo- and endocytic traffic of signaling molecules and receptors. It leads to the reconstruction of organelles such as the Golgi or the nuclear envelope, which decay into fragments during mitosis. Hence, controlled membrane fusion reactions are indispensible for the compartmental organization of eukaryotic cells; for their communication with the environment via hormones, neurotransmitters, growth factors, and receptors; and for the integration of cells into multicellular organisms. Intracellular pathogenic bacteria, such as Mycobacteria or Salmonellae, have developed means to control fusion reactions in their host cells. They persist in phagosomes whose fusion with lysosomes they actively suppress-a means to ensure survival inside host cells. The past decade has witnessed rapid progress in the elucidation of parts of the molecular machinery involved in these membrane fusion reactions. Whereas some elements of the fusion apparatus are remarkably similar in several compartments, there is an equally striking divergence of others. The purpose of this review is to highlight common features of different fusion reactions and the concepts that emerged from them but also to stress the differences and challenge parts of the current hypotheses. This review covers only the endoplasmic fusion reactions mentioned above, i.e., reactions initiated by contacts of membranes with their cytoplasmic faces. Ectoplasmic fusion events, which depend on an initial contact of the fusion partners via the membrane surfaces exposed to the surrounding medium are not discussed, nor are topics such as the entry of enveloped viruses, formation of syncytia, gamete fusion, or vesicle scission (a fusion reaction that leads to the fission of, e.g., transport vesicles).
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillian Magazines Ltd.
    Nature 436 (2005), S. 410-414 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The question concerning whether all membranes fuse according to the same mechanism has yet to be answered satisfactorily. During fusion of model membranes or viruses, membranes dock, the outer membrane leaflets mix (termed hemifusion), and finally the fusion pore opens and the contents ...
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillan Magazines Ltd.
    Nature 396 (1998), S. 575-580 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The basic reaction mechanisms for membrane fusion in the trafficking of intracellular membranes and in exocytosis are probably identical. But in contrast to regulated exocytosis, intracellular fusion reactions are referred to as ‘constitutive’ as no final ...
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) and Rab-GTPases, together with their cofactors, mediate the attachment step in the membrane fusion of vesicles. But how bilayer mixing—the subsequent core process of fusion—is catalysed remains unclear. ...
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1291-1306 
    ISSN: 0009-2940
    Keywords: Semibullvalenes, 1,5-bridged and dimeric ; [4.3.3]Propellanes ; Vinyl sulfides and sulfones ; Nitriles, γ-brominated α,β-unsaturated ; IR spectra, temperature-dependent ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 2,6-Dicyano-1,5-teramethylenesemibullvalenesThe [4.3.3]Propellane-8,11-dione (10) reacts with thiophenols in the presence of titanium tetrachloride/triethylamine to afford equal amounts of the vinyl sulfides C2/Cs-11 (yield 87-93%). Equilibration of the 1:1 mixture of C2/Cs-11 is catalyzed by trifluoroacetic acid and produces a 3:2 ratio of C2- and Cs-11. Sodium perborate tetrahydrate in acetic acid oxidizes the vinyl sulfides C2/Cs-11 to the vinyl sulfones C2/Cs-12 in 81-93% yield. Potassium cyanide on aluminum oxide in boiling 2-methyl-2-butanol converts the 4-chlorosulfones C2/Cs-12b into a mixture of the α,β-unsaturated dinitriles 14-17 and 19, which are separated through chromatography. The intermediates 13 and 18 are isolated in the same way. The major product 14 is brominated by N-bromosuccinimide to afford a mixture of exo-20, endo-20, exo,exo-21, exo,endo-21, endo,endo-21 and 22, which are separated through chromatography. The configurations of the γ-bromodinitriles exo-20 and endo,endo-21 are established by X-ray diffraction analyses. The γ,γ′-dibromodinitrile endo,endo-21 is very reluctant towards the zinc/copper couple as well as powdered lithium. The reaction with tetracarbonylnickel affords a novel semibullvalene dimer for which one of the regioisomeric structures 26 and 27 is proposed. Both γ-bromodinitriles exo-20 and endo-20 are dehydrobrominated by potassium tert-butoxide in ether/tert-butyl alcohol yielding 38% of dicyanosemibullvalene 1c, which closely resembles the non-bridged dicyanosemibullvalene 1a. In the same way the mixture of γ-bromodinitriles, obtained by bromination of 14 with two mol of N-bromosuccinimide, produces 10% of 1c and 28% of bromodicyanosemibullvalene 32 (based on 14) after chromatography. As anticipated, 1c is thermally more stable (up to about 440 K) than 1a lacking the tetramethylene bridge. The IR bands of the nitril groups of 1c undergo a reversible change in the temperature range between 293 and 437 K. This temperature dependence of the IR spectrum appears to be related to the extremely high rate (1011 s-1) of the degenerate Cope rearrangement.
    Notes: [4.3.3]Propellan-8,11-dion (10) reagiert mit Thiophenolen in Gegenwart von Titan(IV)-chlorid/Triethylamin zu gleichen Mengen der Bis(vinylsulfide) C2/Cs-11 (Ausb. 87-93%), die unter Trifluoressigsäure-Katalyse zu einem 3:2-Gemisch äquilibriert werden. Oxidation von C2/Cs-11 mit Natriumperborat-tetrahydrat in Essigsäure ergibt mit 81-93% Ausbeute die Bis(vinylsulfone) C2/Cs-12. Die 4-Chlorsulfone C2/Cs-12b liefern mit Kaliumcyanid auf Aluminiumoxid in siedendem 2-Methyl-2-butanol ein Gemisch der α,β-ungesättigten Dinitrile 14-17 und 19, die chromatographisch getrennt werden. Dabei werden auch die Zwischenstufen 13 und 18 isoliert. Das Hauptprodukt 14 wird mit N-Bromsuccinimid zu einem Gemisch von exo-20, endo-20, exo,exo-21, exo,endo-21, endo,endo-21 und 22 bromiert, das chromatographisch getrennt wird. Die Konfiguration der γ-Bromdinitrile exo-20 und endo,endo-21 wird durch Röntgenstrukturbestimmung geklärt. Das γ,γ′-Dibromdinitril endo,endo-21 reagiert nur sehr träge mit Zink/Kupfer oder Lithiumpulver und mit Tetracarbonylnikkel zu einem neuartigen Semibullvalen-Dimeren, für das eine der regioisomeren Strukturen 26 und 27 vorgeschlagen wird. Beide γ-Bromdinitrile exo-20 und endo-20 werden von Kalium-tert-butylat in Ether/tert-Butylalkohol zu dem Dicyansemibullvalen 1c dehydrobromiert (Ausb. 38%). Das aus 14 mit zwei mol N-Bromsuccinimid erhaltene Gemisch der γ-Bromdinitrile wird auf die gleiche Weise dehydrobromiert und liefert 10% 1c und 28% Bromdicyansemibullvalen 32 (bez. auf 14), die chromatographisch getrennt werden. Erwartungsgemäß ist das Dicyansemibullvalen 1c thermisch stabiler als 1a (bis ca. 440 K), dem die Tetramethylen-Brücke fehlt. Die Nitril-IR-Banden von 1c verändern sich zwischen 293 und 437 K reversibel, was mit der extrem hohen Geschwindigkeit (1011 s-1) der entarteten Cope-Umlagerung zusammenzuhängen scheint.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 68 (1996), S. 1291-1294 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1988 (1988), S. 1155-1163 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Improved Synthesis of 2,6-Dicyano-1,5-dimethylsemibullvalene from 1,5-Dimethylbicyclo[3.3.0]octane-3,7-dioneThe 3,7-diketone 6 reacts with thiophenols in the presense of titanium tetrachloride/triethylamine affording equal amounts of the vinyl sulfides C2/Cs-13 in 87-93% yield. Equilibration of the 1:1 mixture of C2/Cs-13 is catalyzed by trifluoroacetic acid and produces a 3:1 ratio of C2- and Cs-13. Sodium perborate tetrahydrate in acetic acid oxidizes the vinyl sulfides C2/Cs-13 to the vinyl sulfones C2/Cs-14 in almost quantitative yield. Potassium cyanide supported on aluminium oxide in boiling 2-methyl-2-butanol converts the latter into a mixture of the α,β-unsaturated dinitriles 8, 17, Cs-18, 19, 20 which are separated through chromatography. The major product 8 (yield 45-55%) exchanges the allylic protons on treatment with sodium methoxide in methan-[D]ol yielding [D4]-8. Both dinitriles 8 and [D4]-8 are brominated by N-bromosuccinimide in dichloromethane to afford the exo,exo-4,8-dibromodinitriles 22 and [D2]-22, respectively, which are debrominated by means of the zinc/copper reagent. Thus, a 78-85% yield of the 2,6-dicyanosemibullvalenes 1 and [D2]-1, respectively, is achieved on a 2-g scale.
    Notes: Das 3,7-Diketon 6 reagiert mit Thiophenolen in Gegenwart von Titan(IV)-chlorid/Triethylamin zu gleichen Mengen der Bis(vinylsulfide)C2/Cs-13 (Ausb. 87-93%), die unter Trifluoressigsäure-Katalyse zu einem (3:1)-Gemisch äquilibriert werden. Oxidation von C2/Cs-13 mit Natriumperborat-tetrahydrat in Essigsäure ergibt fast quantitativ die Bis(vinylsulfone) C2/Cs-14. Diese liefern mit Kaliumcyanid auf Aluminiumoxid in siedendem 2-Methyl-2-butanol ein Gemisch der α,β-ungesättigten Dinitrile 8, 17, Cs-18, 19, 20, die chromatographisch getrennt werden. Das Hauptprodukt 8 (Ausb. 45-55%) wird durch Behandeln mit Natriummethanolat in Methan-[D]ol an den Allylpositionen deuteriert. Beide Dinitrile 8 und [D4]-8 werden mit N-Bromsuccinimid in Dichlormethan zu den exo,exo-Dibromdinitrilen 22 bzw. [D2]-22 bromiert. Diese werden mit Zink/Kupfer debromiert, wobei im 2-g-Maßstab mit 78-85proz. Ausbeute die 2,6-Dicyansemibullvalene 1 bzw. [D2]-1 erhalten werden.
    Additional Material: 4 Tab.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 515-518 
    ISSN: 0170-2041
    Keywords: Barbaralanes ; Phase transfer catalysis ; Halogenation by hexahaloethanes ; Ring formation by dehydrohalogenation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 2,6-Dicyanobarbaralanes Through Phase Transfer Catalyzed Halogenation/Dehydrohalogenation of Bicyclo[3.3.1]nona-2,6-diene-2,6-dicarbonitrile1)Treatment of bicyclo[3.3.1]nona-2,6-diene-2,6-dicarbonitrile (1) with sodium methoxide in methan-[D]ol or with alkalideuteroxide in deuterium oxide unter the conditions of phase transfer catalysis leads to an exchange of the γ-protons for deuterium atoms producing [D4]-1. This is converted into the barbaralane-dicarbonitrile [D2]-3 by known methods. The carbanion generated from 1 by alkali hydroxide under the conditions of phase transfer catalysis is chlorinated by hexachloroethane. Ring-forming dehydrochlorination of the intermediate chlorinated dinitriles (presumably 2b and 4b) under the same reaction conditions yields predominantly 3 (76%) accompanied by small amounts of the 4-chlorobarbaralanedicarbonitrile 5b (11%), which are separated by chromatography.
    Notes: Durch Natriummethanolat in Methan-[D]ol oder durch Alkalideuteroxid in Deuteriumoxid unter Phasentransfer-Katalyse werden die γ-Protonen des Bicyclo[3.3.1]nona-2,6-dien-2,6-dicarbonitrils (1) gegen Deuterium ausgetauscht. Aus dem so erhaltenen [D4]-1 wird auf bekanntem Weg das Barbaralandicarbonitril [D2]-3 hergestellt. Das mit Alkalihydroxid unter Phasentransfer-Katalyse aus 1 erzeugte Carbanion wird durch Hexachlorethan chloriert. Cyclisierende Dehydrohalogenierung der intermediären chlorierten Dinitrile (vermutlich 2b und 4b) unter den gleichen Reaktionsbedingungen ergibt hauptsächlich 3 (76%) neben 4-Chlorbarbaralandicarbonitril 5b (11%), die chromatographisch getrennt werden.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 106 (1994), S. 1097-1126 
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemische, chromatographische oder spektrometrische Verfahren sind für den Nachweis von Molekülen im Nano- und Subnanogramm-Bereich meist ungeeignet, da ihre Empfindlichkeit zu gering ist. Der 1959 von Yalow und Berson entwickelte Radioimmunoassay (RIA) verband erstmals die hohe Nachweisempfindlichkeit radioaktiv markierter Substanzen mit der großen Spezifität immunologischer Reaktionen. Dadurch war es möglich, geringste Spuren von Substanzen in Gegenwart eines Überschusses an teilweise sehr ähnlichen Fremdstoffen ohne vorherige Anreicherung quantitativ nachzuweisen. Immunoassays entwickelten sich zum wohl wertvollsten analytischen Instrument der In-vitro-Diagnostik und werden heute routinemäßig zum Nachweis körpereigener und körperfremder Stoffe (z.B. Hormone, tumorassoziierte Proteine, Bakterien, Viren, Toxine und Arzneimittel) eingesetzt. Die vielfältigen Nachteile der Radioaktivität wie erforderliche Umgangsgenehmigungen, Entsorgungskosten, Vorkehrungen zur Vermeidung gesundheitlicher Risiken, kurze Haltbarkeit und begrenzte Sensitivität führten schon früh zur Suche nach anderen, nichtradioaktiven Markierungsmöglichkeiten. Begünstigt durch die Entwicklung der Lichtmeßtechnik und der kommerziellen Verfügbarkeit von hochempfindlichen Meßgeräten verdrängen heute Enzyme, Fluorophore und Luminophore als Marker zunehmend die radioaktiven Isotope. Einige der neuen Lumineszenzmarker ermöglichen aber nicht nur einen Ersatz von Radioisotopen, sondern auch einen Vorstoß in bisher unerreichte Empfindlichkeitsregionen. Der folgende Artikel soll eine Übersicht über die Möglichkeiten der Lumineszenzmarkierung und ihre Anwendungen vorwiegend im Bereich der Immunoassays geben.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 33 (1994), S. 1044-1072 
    ISSN: 0570-0833
    Keywords: Luminescence ; Immunoassays ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemical, chromatographic, or spectrometric methods are generally unsuitable for the detection of molecules in the nano and subnanogram region because of their low sensitivity. The radioimmunoassay (RIA) developed by Yalow and Berson in 1959 combined the high sensitivity of radioactively labeled substances with the high specificity of immunological reactions for the first time. In this way it was possible to detect quantitatively the tiniest traces of substances in the presence of an excess of other, in some cases, similar foreign substances without prior enrichment. Immunoassays have certainly developed to become the most valuable analytical tool of in vitro diagnostics and are today routinely employed for the detection of endogenous and exogenous substances (e.g. hormones, tumor-associated proteins, bacteria, viruses, toxins, drugs, etc). The many disadvantages of radioactivity such as the required handling licenses, disposal costs, precautions necessary to prevent risks to health, short shelf-life, and limited sensitivity soon led to the search for other nonradioactive labeling methods. Encouraged by the development of light measuring techniques and the commercial availability of highly sensitive apparatus, radioactive isotopes as labels are today being replaced increasingly by enzymes, fluorophores, or luminophores. Some of the new luminescent labels have, however, not only facilitated replacement of radioisotopes, but also a breakthrough into what has until now been unattainable levels of sensitivity. The following article reviews the methods of luminescent labeling and their applications mainly in the area of immunoassays.
    Additional Material: 13 Ill.
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