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  • 1
    Electronic Resource
    Electronic Resource
    Stoffwechselprodukte von Mikroorganismen (1973)
    Springer
    Archives of microbiology 92 (1973), S. 285-300 
    Details
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Bei Neurospora crassa, arg-5, ota, aga wird die Desferricoprogenbildung durch Zusatz von Fe3+, Ga3+, Al3+ und V3+ im Medium unterdrückt. Bei Anwesenheit von Cr3+ und Co3+ verhält sich die Mutante wie unter Eisenmangelbedingungen. Eine angelaufene Coprogenbiosynthese wird innerhalb von 24 h mit Fe-Coprogen (10 μM), Ga-Coprogen (10 μM) und Al-Coprogen (〉100 μM) reprimiert. Die Coprogenaufnahme entspricht einer Sättigungskinetik, die Aufnahme von Desferricoprogen und Fe3+ folgt dagegen einer Diffusionsgeraden. Die verschiedenen Metall-Coprogene verhalten sich bei der Aufnahme kompetitiv und werden nach folgender Affinitätsreihe angereichert: Ga〉Fe〉Al〉V〉Cr〉Co. Die gleiche Reihenfolge wird eingehalten bei der Regulation der Desferricoprogenbiosynthese. Ein Modell für die Aufnahme, das auf der Stabilität der Metall-Coprogene basiert, wird vorgeschlagen.
    Notes: Summary The production of desferricoprogen in Neurospora crassa, arg-5, ota, aga is suppressed by addition of Fe3+, Ga3+, Al3+, and V3+ to the medium. In the presence of Cr3+ and Co3+, the mutant behaves as under iron-deficient conditions. Once started, the biosynthesis of coprogen is suppressed within 24 h by Fe-Coprogen (10 μM), Ga-Coprogen (10 μM), and Al-Coprogen (〉100 μM). The uptake of Coprogen corresponds to a saturation kinetic, whereas the uptake of desferricoprogen and Fe3+ is in accordance with a diffusion line. The different metal analogues of coprogen exhibit competitive behavior during the uptake, and are concentrated by the cells in the following order of affinity: Ga〉Fe〉Al〉V〉Cr〉Co, which seems to be the same sequence in the regulation of the desferricoprogen biosynthesis. A model for uptake, based on the stability of the metal coprogens, is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00409282
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  • 2
    Electronic Resource
    Electronic Resource
    Metabolic products of microorganisms (1974)
    Springer
    Archives of microbiology 98 (1974), S. 39-50 
    Details
    ISSN: 1432-072X
    Keywords: Iron Transport ; Sideramines ; Neurospora ; Aspergillus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The transport of 55Fe3+, mediated by various fungal sideramines, was tested using an ornithine-deficient mutant of Neurospora crassa (arg-5, ota, aga), which can be cultivated completely free of its own sideramines. We have found that Neurospora crassa is able to accumulate iron by its own chelate coprogen (K m∼20 μM, V max∼1.74 nmol/mg min) and also by the two exogenous sideramines ferricrocin (K m∼5 μM, V max∼0.22 nmol/mg min) and ferrichrysin (K m∼20 μM, V max∼0.4 nmol/mg min) produced by members of the genus Aspergillus. Other sideramines like ferrichrome, ferrichrome A, and ferrirubin were relatively ineffective as iron transport molecules for this organism. Competitive inhibition of coprogen uptake was observed with all ferrichrome-group compounds: ferrichrysin (K i∼140 μM), ferrichrome and ferricrocin (K i∼5 μM). Ferrirubin (K i∼0.5 μM) was the strongest inhibitor of coprogen uptake in Neurospora crassa. Inhibition experiments indicate that ferrirubin may possibly block the uptake of coprogen and ferrichrome-type compounds by occupying the receptor sites without being preferably transported. For further characterisation of the coprogen uptake system in Neurospora crassa comparative uptake experiments were performed with the parent wild-type strain 74 A, and with a ferricrocin-producing Aspergillus fumigatus strain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425266
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  • 3
    Electronic Resource
    Electronic Resource
    Stoffwechselprodukte von Mikroorganismen (1974)
    Springer
    Archives of microbiology 100 (1974), S. 329-340 
    Details
    ISSN: 1432-072X
    Keywords: Bone Marrow Cells ; Iron Transport ; Sideramines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung An in vitro kultivierten Knochenmarkzellen (Detroit-98) wurden Versuche zur Aufnahme von Eisen aus 55Fe-markiertem Transferrin, Eisencitrat, Fusigen, Coprogen, Ferrichrom, Ferricrocin, Ferrichrysin, Ferrirubin und Ferrioxamin B durchgeführt. Von den eingesetzten Sideraminen wurden Fusigen und Ferricrocin besonders gut angereichert. Transferrin, Ferrioxamin B und Ferricrocin zeigten im untersuchten Konzentrationsbereich (0,5–8,0 μM) eine Sättigungskinetik. Die Aufnahme aller übrigen untersuchten Eisenkomplexe ergab im V/S-Diagramm eine lineare Beziehung. Nach 1 Std Aufnahme wurden in den Zellen Anreicherungen des angebotenen Eisens gemessen, die für Eisencitrat das ca. 60fache, für Fusigen und Ferricrocin das ca. 20fache und für Transferrin und die übrigen Pilzsideramine das ca. 6fache der äußeren Konzentration betrugen. Im Gegensatz zu Transferrin und Ferricrocin war die Aufnahme durch Eisencitrat und Fusigen temperaturabhängig. Eine pH-Abhängigkeit wurde nicht beobachtet. Effluxmessungen zeigten, daß der größte Teil des aufgenommenen Eisens in den Zellen gebunden war und durch Lyse nicht freigesetzt werden konnte.
    Notes: Abstract The uptake of iron from 55Fe-labeled transferrin, ferric citrate, fusigen, coprogen, ferrichrome, ferricrocin, ferrichrysin, ferrirubin and ferrioxamine B was studied on in vitro cultures of bone marrow cells (Detroit-98). From all supplied iron complexes of the sideramine type, fusigen and ferricrocin were especially well accumulated. Transferrin, ferrioxamine B and ferricrocin showed a saturation kinetic within the investigated concentration range (0.5–8.0 μM). For all other iron complexes a linear relationship in the V/S-plot could be observed. After 1 hr uptake the iron content of the cells was approximately the 60-fold of the outer concentration for ferric citrate, the 20-fold for fusigen and ferricrocin and the 6-fold for transferrin and the other sideramines. Uptake of ferric citrate and fusigen was temperature dependent. A pH-dependence could not be observed. Efflux measurements revealed that the largest part of the accumulated iron was retained inside the cell and could not be released by osmotic lysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00446326
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  • 4
    Electronic Resource
    Electronic Resource
    Stoffwechselprodukte von Mikroorganismen (1973)
    Springer
    Archives of microbiology 88 (1973), S. 49-60 
    Details
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Mit einer Ornithinmangelmutante von Neurospora crassa, arg-5, ota, aga, deren Sideraminbildung vollständig blockiert ist, wurde die Aufnahme von verschiedenen Sideraminen und von Eisencitrat untersucht. Ferrioxamin oxamin B sowie N-Acetyl-ferrioxamin B (Ferrioxamin D1) und N-Benzoyl-ferrioxamin B werden von Neurospora-Zellen nicht angereichert. Die transportkinetischen Daten zeigen, daß Neurospora crassa unter Eisenmangelbedingungen zwei voneinander differenzierbare Eisentransportsysteme ausbildet: das Coprogensystem und das Eisencitratsystem.
    Notes: Summary With an ornithine-deficient mutant of Neurospora crassa, arg-5, ota, aga, whose sideramine production is completely blocked, the uptake of various sideramines and iron citrate was studied. Ferrioxamine B, as well as N-acetyl-ferrioxamine B (ferrioxamine D1) and N-benzoyl-ferrioxamine B were not accumulated by the cells of Neurospora. The kinetic data of transport indicate, that under iron-deficient conditions Neurospora evolves two distinguishable iron-transport systems: the coprogen system and the iron citrate system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00408840
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  • 5
    Electronic Resource
    Electronic Resource
    Metabolic products of microorganisms (1974)
    Springer
    Archives of microbiology 100 (1974), S. 271-282 
    Details
    ISSN: 1432-072X
    Keywords: Iron Transport ; Neurospora ; Sideramine Derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Different derivatives of coprogen B (desacetyl coprogen) and coprogen were prepared to study their iron transport properties in Neurospora crassa arg-5, ota, aga. With increasing N-acyl chain length the rates of iron chelate uptake could significantly be enhanced in the order N-acetyl-〈N-propionyl-〈N-butyryl coprogen B. However, more bulky phenyl derivatives and lipophilic, charge carrying N-acyl derivatives again decreased the uptake rates, although their affinity to the uptake system is increased. On the other hand, structural alterations of the two OH-groups of the anhydromevalonic moieties, like di-O-acetylation and di-O-sucinylation revealed no improvement of the chelate uptake. Di-O-acetyl coprogen showed similar transport properties like coprogen, whereas di-O-succinyl coprogen exhibited a remarkably lower affinity to the coprogen uptake system in Neurospora crassa. The results suggest that the coprogen molecule requires a special hydrophobic area for optimal orientation during uptake and iron release.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00446323
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    Paper (German National Licenses)
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