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  • Articles  (4)
  • Wiley-Blackwell  (4)
  • 1980-1984  (4)
  • 1
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (±)-Muscone (5) has been synthesized from methyl 13-(chloroformyl)tridecanoate (6) in nine steps in an overall yield of 24%. The key steps involve an efficient transformation of the readily accessible 14-hydroxy-15-methyl-15-hexadecenoic acid (9) into the tetradecanolide 1 and a subsequent Ireland-Claisen rearrangement of its triethylsilyl enolate 2 to a 8:1-mixture of the stereoisomeric 15-membered carbocycles 4 and 10 (Scheme 4).
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Factor F430 from Methanogenic Bacteria: Structure of the Protein-free FactorFactor F430, the porphinoid nickel-containing coenzyme of the methylcoenzyme-M reductase of metanogenic bacteria is shown to be the 33,83,122,133,182-pentaacid derivative of the pentamethylester F430M, the structure of which had been determined previously (see structural formulae 1 and 2). The structure assignment rests on chromatographic, UV/VIS-, CD-, IR-, and 13C-NMR-spectroscopic as well as FAB-mass spectral comparision of F430 with F430M and the pentaacid prepared by acid-catalyzed hydrolysis of F430M.In the cells of Methanobacterium thermoautotrophicum, factor F430 is present in a ‘bound’ and also, depending on the growth conditions, in ‘free’ form, the latter being defined as the part of total F430 that can be extracted from the cells under extremely mild conditions (80% EtOH at 0-4°). From the (protein)-‘bound’ form, F430 is extracted by subsequently treating the cells at 0-4° with 80% EtOH containing (e.g.), 2m LiCi.From both sources, the extracted factor is the same pentaacid, and there is no indication for the existence of a protein-free F430 species that would contain additional (covalently bound) structural elements.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Factor F430 from Methanogenic Bacteria: Structure of the Porphninoid Ligand SystemA structure is proposed for F430M, a non-cristalline methanolysis product of isolates of the nickel-containing, porphinoid factor F430 from Methanobacterium thermoautotrophicum.Crucial to the structure determination are five incorporation experiments with M. thermoautotrophicum (strain Marburg) in which the specifically mono-13C-labeled biosynthetic precursors (2-13C), (3-13C), (4-13C)-, (5-13C) ALA (ALA = δ-amino-levulinic acid) and L-(methyl-13C)methionine were incorporated into F430 with high efficiency. The 13C-NMR,-spectra of the specifically labeled F430M samples derived therefrom, together with the UV./VIS. spectral data of F430M, contain all the information necessary for the deduction of the constitution of the F430M chromophore, assuming the established pattern of porphinoid biosynthesis to be operative in F430 biosynthesis. 1H-NMR. spectroscopy and, in particular, 1H-NMR.-NOE-difference spectroscopy corroborates and completes the constitutional assignments and, furthermore, makes possible an almost complete derivation of the molecule's relative configuration. Schemes 3 and 4 summarize the results of 1H-NMR. spectroscopy, presenting them within the context of the proposed structure for F430M. The assignment of absolute configuration implied in the formula is given preference because of F430M's very close structural and (assumed) biosynthetic relationship to sirohydrochlorin and vitamin B12 (with respect to ring C, the assignment is based on degradative evidence).According to the proposed structure, the nickel complex F430M possesses an uroporphinoid (Type III) ligand skeleton with an additional carbocyclic ring and a chromophore system not previously encountered among natural porphinoids. It can be considered to be a (tetrahydro) derivative of the corphin system, combining structural elements of both porphyrins and corrins.
    Additional Material: 10 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Supramolecular Structure and Cellular Biochemistry 17 (1981), S. 1-9 
    ISSN: 0275-3723
    Keywords: cell aggregation ; aggregation factor ; sponges ; glycoproteins ; Chemistry ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Antibodies were raised against the purified aggregation factor from Geodia cydonium in order to clarify its function during cell aggregation in the homologous and heterologous system. These antibodies inhibited only cell aggregation in the homologous Geodia system and were inactive in the heterologous Tethya lyncurium system. These findings directly indicated that the species-specific reaggregation of sponge cells was initiated by the soluble aggregation factor as already assumed in earlier studies. The amount of neutralizing antibodies was determined by a precipitation reaction with the antigen in capillaries and by microdiffusion. By using the latter technique we got evidence that the Geodia aggregation factor contained a component that was antigenetically related to a galactose-specific lectin present in Geodia cydonium.
    Additional Material: 5 Ill.
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