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'Biosynthesis' in keywords Facet   section ZfN Section B  [X]
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1984 (1)
1981 (1)
1Author    NicolaasJ. De Mola, Johannes Reischb, G. Erardus, M. J. Beijersbergen, H. EnegouwRequires cookie*
 Title    On the Involvement of Singlet Oxygen in the Biosynthesis of Oxygenation Products of the Furocoumarin Imperatorine  
 Abstract    The role of singlet oxygen (' 0 2) in the photo-oxidation of the furocoumarin im peratorine was investigated in vitro. Irradiation with visible light and sensitization with methylene blue yielded the im peratorine oxidation product isogosferol and the corresponding ketone as main products. The involvement of ' 0 2 was dem onstrated by studying the rate of oxidation under conditions that affect the lifetime of ' 0 2. Com pared to a range of other furocoum arins, im peratorine appeared to be m oderately active as a '0 2 generator. The extent of ' 0 2 production correlated with the skin sensitizing activity. U pon irradiation of im peratorine itself with U VA light (360 nm) no isogos­ ferol formation is observed, probably as a consequence of its photochem ical instability. Irradia­ tion with visible light (A > 4 0 0 nm) of a chlorophyll chrom ophore containing sensitizer in the presence of im peratorine, yielded isogosferol and the corresponding ketone product. This dem on­ strates that in the form ation of ' 0 2 oxidation products of im peratorine in plants naturally occuring sensitizers e.g. chlorophyll and visible light are involved, rath er than ' 0 2 produced by im peratori-ne or other furocoumarins and U VA light. The protective effect on the chlorophyll sensitized im peratorine oxidation by the ' 0 2-and chlorophyll triplet quencher /3-carotene was dem onstrated in a lipophilic solvent. 
  Reference    Z. Naturforsch. 39b, 1433 (1984); received D ecem ber 12 1983 
  Published    1984 
  Keywords    Singlet Oxygen, Biosynthesis, Im peratorine, Isogosferol, Photo-oxygenation 
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 TEI-XML for    default:Reihe_B/39/ZNB-1984-39b-1433.pdf 
 Identifier    ZNB-1984-39b-1433 
 Volume    39 
2Author    H.-R SchultenRequires cookie*
 Abstract    A combined 13 C nuclear magnetic resonance and field desorption mass spectrometric investigation of algae grown on 13 C02 has shown that the isotopic enrichment of amino acids extracted therefrom is neither uniform nor statistical. The use of these two indepen-dent techniques allows a new, detailed and accurate insight into the label distribution resulting from biosynthesis. The observed deviations from the statistical abundances are systematic. A system for classifying each member of the complex ensemble of isotopic species has been devised, so that the isotopomers may be ordered according to their relative probability of occurrence. 
  Reference    Z. Naturforsch. 36b, 1289—1296 (1981); received May 20 1981 
  Published    1981 
  Keywords    13 C Enriched Amino Acids, Biosynthesis, Label Distribution, NMR Spectra, Field Desorption Mass Spectrometry 
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 TEI-XML for    default:Reihe_B/36/ZNB-1981-36b-1289.pdf 
 Identifier    ZNB-1981-36b-1289 
 Volume    36