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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 99 (1966), S. 642-652 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Die Synthese von β.β′-disubstituierten Divinyläthern und Divinylthioäthern durch Wittig-Reaktion wird beschrieben. Die entstehenden cis.trans-Isomeren werden getrennt und durch ihre IR- und NMR-Spektren charakterisiert. Die arylsubstituierten Divinyläther sind beständige Verbindungen und werden selbst durch Kochen mit starken Säuren nicht oder nur langsam gespalten.
    Additional Material: 2 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 99 (1966), S. 634-641 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Darstellung und Eigenschaften des Dimethyläther-α.α′-bis-triphenylphosphoniumbromids und dessen Kondensation zu Derivaten des Oxepins und Furans werden beschrieben.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 86 (1974), S. 624-634 
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ribonucleotid-Reduktasen sind Enzyme, die in teilungsfähigen Zellen die für die DNA-Verdoppelung benötigten Desoxyribonucleotide synthetisieren. Sie besitzen damit eine Schlüsselfunktion für das Wachstum von Mikroorganismen sowie aller pflanzlichen und tierischen Gewebe. Die Enzyme reduzieren alle vier Purin- und Pyrimidinribonucleotide (als 5′-Di- oder -Triphosphate) unter direkter Substitution der 2′-Hydroxygruppe durch Wasserstoff. Physiologische Reduktionsmittel sind die Mercaptogruppen der Thioredoxine, einer Gruppe kleiner Proteine, die aus der oxidierten Form durch NADPH-abhängige Thioredoxin-Reduktasen regeneriert werden. Man kennt zwei Typen von Ribonucleotid-Reduktasen (I und II), die die Wasserstoffübertragung mit Hilfe proteingebundener Eisen-Ionen oder des 5′-Desoxyadenosylcobalamins (Coenzym B12) katalysieren; in beiden Fällen sind ferner Radikale nachweisbar. Zur Regulation der Enzyme dienen Effektornucleotide. Möglicherweise liegt ein homöostatischer Mechanismus vor, der die Versorgung der Zelle mit DNA-Vorläufern sicherstellt.
    Additional Material: 6 Ill.
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  • 4
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 2530-2544 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Properties of 5′-Deoxynucleoside 5′-Carboxylic Acids and DerivativesA preparative route to 5′-deoxynucleosid- 5′-carbonitriles (3), both of the ribose and deoxyribose series, involves crown ether-catalyzed reaction of nucleoside 5′-tosylates with solid potassium cyanide in organic solvents. O2,5′-Cyclo derivatives of pyrimidine nucleosides can also serve as starting materials. The nitriles 3 require acidic conditions for conversion to the esters 6 of 5′-deoxynucleoside 5′-carboxylic acids (7) which are suitable nucleotide models for biochemical studies. In alkaline solutions compounds 3 undergo rapid elimination of the purine or pyrimidine base. Furthermore the adenine derivative 3a, under addition of the unsaturated sugar fragment 10 yields a new nucleoside 12 in which N6 is inserted in a pyrrolidine ring. The circular dichroism spectra of the new compounds reflect strong electronic interaction between polar C-5′-substituents and the chromophores and are in line with those of other C-5′-modified nucleosides.
    Notes: Die Darstellung von bisher nicht allgemein zugänglichen 5′-Desoxynucleosid-5′-carbonitrilen (3) gelingt sowohl in der Ribo- wie 2′-Desoxyribonucleosidreihe, wenn man Nucleosid-5′-tosylate mit festem KCN unter Kronenether-Katalyse in organischen Lösungsmitteln umsetzt. Auch O2, 5′-Cyclopyrimidinnucleoside eignen sich als Ausgangsmaterial. Aus den Nitrilen 3 sind unter vorzugsweise sauren Reaktionsbedingungen die Ester 6 und aus ihnen die 5′-Desoxynucleosid-5′-carbonsäuren (7) erhältlich, die sich als Nucleotid-Modelle in biochemischen Systemen eignen. In alkalischer Lösung erleiden die Nitrile 3 rasche Eliminierung der Purin- oder Pyrimidinbase. Aus dem Adeninnucleosid 3a entsteht dabei ferner unter Addition des ungesättigten Zuckerfragmentes 10 das an N6 zu einem Pyrrolidin modifizierte Nucleosid 12. Wie in anderen C-5′-modifizierten Nucleosiden zeigen die Circulardichroismus-Spektren der neuen Verbindungen eine starke elektronische Wechselwirkung zwischen polaren C-5′-Substituenten und den Chromophoren an.
    Additional Material: 3 Ill.
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  • 7
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 13 (1974), S. 569-579 
    ISSN: 0570-0833
    Keywords: Ribonucleotides ; Nucleotides ; Biosynthesis ; Enzymes ; Deoxyribonucleotides ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ribonucleotide reductases are enzymes that synthesize the deoxyribonucleotides required for the replication of DNA in dividing cells. They thus have a key function for the growth of microorganisms and of all plant and animal tissues. The enzymes reduce all four purine and pyrimidine ribonucleotides (as the 5′-diphosphates or triphosphates) with direct substitution of the 2′-hydroxyl group by hydrogen. The physiological reducing agents are the mercapto groups of thioredoxins, a group of small proteins, which are regenerated from the oxidized form by NADPH-dependent thioredoxin reductases. There are two known types of ribonucleotide reductases (I and II), which catalyze hydrogen transfer with the aid of protein-bound iron ions or of 5′-deoxyadenosylcobalamin (coenzyme B12); free radicals can be detected in both cases. The enzymes are regulated by effector nucleotides. There may exist a homeostatic mechanism, which guarantees the supply of DNA precursors to the cell.
    Additional Material: 6 Ill.
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  • 9
    ISSN: 0173-0835
    Keywords: Thioredoxin ; Denaturing electrophoresis ; High performance capillary electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Disulfide containing proteins - thioredoxins from E.coli and pig heart mitochondria - were characterized by sodium dodecyl sulfate (SDS)-electrophoresis and high performance capillary electrophoresis (HPCE). Following the mitochondrial thioredoxin samples at different stages of purification, we found that their electrophoretic patterns vary, dependent on the redox condition of isolation, preparation of the samples for SDS-electrophoresis, and sample storage. All these factors influenced the relative intensities of several protein bands with thioredoxin-like mobility, whereas the sample storage also resulted in the appearance of SDS- and dithiothreitol (DTT)-resistant high molecular mass forms, probably thioredoxin dimers. The multiple forms of the thioredoxin from pig heart mitochondria in SDS-electrophoresis might be dependent on the oxidation state of the protein cysteine residues. A commercial preparation of the thioredoxin from E.coli did not exhibit any changes in mobility in SDS gels whether the sample was prepared with or without DTT. After the final purification step no correlation was found between mitochondrial thioredoxin activity, determined in the insulin assay, and its purity in SDS-electrophoresis. A correlation was, however, found when analyzing the thioredoxin by HPCE. The latter approach demonstrated the heterogeneity of the thioredoxin samples homogeneous on SDS electrophoresis, only one of the several HPCE peaks being active in the insulin assay. Also, thioredoxin from E.coli, homogeneous on SDS-electrophoresis, was found heterogeneous on HPCE. The peak corresponding to the insulin-dependent thioredoxin activity was split into two by DTT treatment, suggesting that redox transformations of thioredoxin could be followed by HPCEPresented at the “Elektrophorese Forum “96” meeting of the German Electrophoresis Society, held at the Technical University Munich, October 23-25, 1996.
    Additional Material: 7 Ill.
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  • 10
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Tab.
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