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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Phytochemistry 29 (1990), S. 393-397 
    ISSN: 0031-9422
    Keywords: Beta vulgaris ; Chenopodiaceae ; cell wall ; suspension culture ; vacuoles ; α-mannosidase.
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Molecular genetics and genomics 261 (1999), S. 1012-1020 
    ISSN: 1617-4623
    Keywords: Key words Porphyrin biosynthesis ; Protoporphyrinogen oxidase ; Coproporphyrinogen oxidase ; Overexpression ; Enzymatic conversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Protoporphyrinogen oxidase, the penultimate enzyme involved in the biosynthetic pathway for heme, catalyzes the removal of six electrons from protoporphyrinogen IX to generate protoporphyrin IX. In Escherichia coli, this enzyme is encoded by the hemG gene. In this study we examined possible alternate pathways for the oxidation of protoporphyrinogen IX to protoporphyrin IX, by isolating and investigating E. coli mutants that can still grow normally when the hemG gene is disrupted. One of these mutants was characterized in detail and had a mutation in the promoter region of the hemF gene, which encodes aerobic coproporphyrinogen oxidase, the enzyme involved in the step immediately before protoporphyrinogen oxidase. Measurement of the promoter activity of the hemF gene showed that the level of transcription was elevated by the mutation. Overexpression of a wild-type hemF gene cloned in a multicopy plasmid also restored the growth of ΔhemG strain. Extracts from cells that overexpress hemF exhibited an increased ability to oxidize protoporphyrinogen IX to protoporphyrin IX. These findings suggest that the E. coli aerobic coproporphyrinogen oxidase has an intrinsic capacity to oxidize not only coproporphyrinogen III but also protoporphyrinogen IX.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    European archives of oto-rhino-laryngology and head & neck 251 (1994), S. 224-228 
    ISSN: 1434-4726
    Keywords: Capsaicin ; Histamine ; Nasal airway resistance ; Nasal secretion ; Guinea pigs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We studied serial changes of nasal airway resistance (NAR) and secretory response after topical stimulation with either capsaicin or histamine, since both are known to stimulate a chemosensitive sensory C-fiber ending. After topical capsaicin stimulation, a dose-related increase of NAR was noted, with a peak response occurring at 10–20 min. These NAR responses were completely abolished following systemic pretreatment with capsaicin. However, they were not affected by atropine, diphenhydramine or hexamethonium pretreatment. After topical histamine stimulation, an atropine-resistant increase of NAR was found and continued more than 120 min. The early phase of this response was significantly suppressed by the systemic pretreatment with capsaicin. A secretory response also occurred after topical capsaicin stimulation and continued for 30 min. This secretory response was almost completely blocked by atropine, hexamethonium or systemic capsaicin pretreatment and was partially suppressed by diphenhydramine pretreatment. These findings suggest that sensory C-fiber stimulation can induce both atropine-resistant vascular reflexes and atropine-sensitive secretory reflexes, and that these reflexes might play an important role during the early phase after nasal stimulation.
    Type of Medium: Electronic Resource
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