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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 132 (1982), S. 155-158 
    ISSN: 1432-072X
    Keywords: Vitamin B12 ; 5,6-Dimethylbenzimidazole biosynthesis ; 5-Methoxybenzimidazole ; Corrin precursor ; Ripoflavin ; Bacillus megaterium ; Nocardia rugosa ; Clostridium barkeri ; Eubacterium limosum ; Clostridium thermoaceticum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Radioactivity from [1′-14C]riboflavin was incorporated into the 5,6-dimethylbenzimidazole moiety of Vitamin B12 in the aerobes Bacillus megaterium, Nocardia rugosa and Streptomyces sp. as well as in the aerotolerant anaerobe Propionibacterium freudenreichii, but not in the anaerobe Eubacterium limosum. As recently published for E. limosum, also in the anaerobe Clostridium barkeri radioactivity from [1-14C]glycine and [2-14C]glycine was found in the 5,6-dimethylbenzimidazole moiety, but not in the corrin moiety. The addition of l-[methyl-14C]methionine to C. barkeri led to the labeling of the corrin moiety and the 5,6-dimethylbenzimidazole moiety, showing that the seven “extra” methyl groups in the corrin ring as well as the two methyl groups of the base part originate from this precursor. In Clostridium thermoaceticum, forming the vitamin B12 analog 5-methoxybenzimidazolylcobamide, [1-14C]glycine and [2-14C]glycine were also incorporated into the 5-methoxybenzimidazole moiety, but not into the corrin ring. In E. limosum l-[U-14C]glutamate led to the labeling of the corrin ring of vitamin B12, but not of its base moiety. There results together with data from the literature indicate that a common biosynthetic pathway might exist for the corrinoid biosynthesis in aerobic microorganisms, and in those aerotolerant anaerobes like the Propionibacteria, which form the 5,6-dimethylbenzimidazole moiety of vitamin B12 only under aerobic conditions. They also show that this pathway differs from the pathway found in anaerobic bacteria.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-072X
    Keywords: 5-Hydroxybenzimidazolylcobamide ; Vitamin B12-factor III ; Coenzyme F420 ; Methanosarcina barkeri ; Archaebacterium ; Corrin precursor ; C-5 pathway ; Glycine ; Glutamate ; Eubacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Exogenous 5-hydroxy-[2-14C]benzimidazole was transformed by Methanosarcina barkeri into 5-hydroxy-[2-14C]benzimidazolylcobamide. Thereby the endogenous biosynthesis of 5-hydroxybenzimidazole was completely blocked. Benzimidazole and 5,6-dimethylbenzimidazole were used by M. barkeri to form benzimidazolylcobamide respectively 5,6-dimethylbenzimidazolylcobamide (vitamin B12), but in these cases the endogenous biosynthesis of factor III was not completely suppressed. With [2-14C]benzimidazole it was demonstrated that this base as well as the benzimidazolylcobamide formed thereof are no precursors in the biosynthesis of 5-hydroxybenzimidazolylcobamide. Glycine instead was found to be a building block for the biosynthesis of 5-hydroxybenzimidazole, since radioactivity from [1-14C] and [2-14C]glycine was incorporated, into the base moiety of factor III, but not into its corrin moiety. With [1-13C]glycine and 13C-NMR-spectroscopy it was shown that C-1 of glycine gets C-3a of 5-hydroxybenzimidazole. [1-13C]glycine also led to a single prominent signal in the 13C-NMR-spectrum of coenzyme F420, this was assigned to C-10a. Thus C-1 of glycine was incorporated into the hydroxybenzene part of 5-hydroxybenzimidazole, whereas it was not incorporated into this part of coenzyme F420, indicating that the hydroxybenzene part of these two compounds is not formed from a common intermediate. L-[U-14C]glutamate led to the exclusive labeling of the corrin ring of factor III, showing that the corrin precursor 5-aminolevulinic acid is formed by the C-5 pathway in M. barkeri. These experiments indicate that the biosynthesis of factor III in the “archaebacterium” M. barkeri is similar to the corrinoid biosynthesis in the anaerobic “eubacteria” Eubacterium limosum, Clostridium barkeri, and Clostridium thermoaceticum.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-072X
    Keywords: Desulfovibrio vulgaris ; Corrinoids ; Guanylcobamide ; Hypoxanthylcobamide ; Pseudovitamin B12 ; Vitamin B12 ; Sulfate-reducing bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The corrinoids synthesized by the sulfate-reducing bacterium Desulfovibrio vulgaris were analyzed. The compounds found were guanylcobamide and hypoxanthylcobamide; structures were determined by mass spectrometry, 1H-NMR, and ultraviolet/visible spectroscopy. D. vulgaris used externally added guanine to form guanylcobamide, as demonstrated with 8-14C-guanine. Addition of adenine did not lead to the formation of adenylcobamide (pseudovitamin B12), whereas 5,6-dimethylbenzimidazole was transformed into vitamin B12.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 7 (1980), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 5
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    Unknown
    Roslyn Heights, N.Y. : Periodicals Archive Online (PAO)
    Adolescence. 8:32 (1973:Winter) 463 
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 729 (1969), S. 231-233 
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Oxidative Degradation of 5,6-DimethylbenzimidazolePrior to carrying out tracer experiments used in the investigation of the biosynthesis of 5,6-dimethylbenzimidazole (1) methods for its degradation had to be worked out. In order to identify all C-atoms, 1 had to be degraded by two procedures: The Kuhn-Roth degradation yields acetic acid and CO2. The acetic acid undergoes Schmidt degradation thus allowing the identification of C-5, C-6, and the methyl groups of 1. - The oxidation of 1 with K2Cr2O7 yields imidazole-4,5-dicarboxylic acid (4) which after decarboxylation gives imidazole and CO2. Thus C-2, C-8, and C-9 on the one hand and C-4 and C-7 on the other hand can be identified.
    Notes: Für Tracerversuche zur Biosynthese von 5.6-Dimethyl-benzimidazol (1) wurde 1 oxydativ abgebaut. Die Identifizierung sämtlicher C-Atome gelingt nur durch Abbau nach zwei Methoden: Der Kuhn-Roth-Abbau führt zu Essigsäure und CO2. Durch anschließenden Schmidt-Abbau der Essigsäure können C-5, C-6 und die Methyl-Gruppen von 1 identifiziert werden. - Die Oxydation mit Kaliumdichromat führt zu Imidazol-dicarbonsäure-(4.5) (4), deren Decarboxylierung zu Imidazol und CO2 die Identifizierung von C-2, C-8 und C-9 bzw. C-4 und C-7 erlaubt.
    Type of Medium: Electronic Resource
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