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1984 (1)
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1Author    E. F. Elstner, H. P. Fischer, W. Osswald, G. KwiatkowskiRequires cookie*
 Title    Superoxide-and Ethane-Formation in Subchloroplast Particles: Catalysis by Pyridinium Derivatives  
 Abstract    Oxygen reduction by chloroplast lamellae is catalyzed by low potential redox dyes with E'0 values between -0 .3 8 V and -0 .6 V. Compounds o f E'0 values o f -0 .6 7 V and lower are inactive. In subchloroplast particles with an active photosystem I but devoid of photosynthetic electron transport between the two photosystems, the active redox compounds enhance chlorophyll bleaching, superoxide formation and ethane production independent on exogenous substrates or electron donors. The activities o f these compounds decrease with decreasing redox potential, with one exception: 1-methyl-4,4'-bipyridini urn bromide with an E'0 value o f lower -1 V (and thus no electron acceptor o f photosystem I in chloroplast lamellae with intact electron transport) stimulates light dependent superoxide formation and unsaturated fatty acid peroxidation in sub­ chloroplast particles, maximal rates appearing after almost complete chlorophyll bleaching. Since this activity is not visible with compounds with redox potentials below -0 .6 V lacking the nitrogen atom at the 1-position o f the pyridinium substituent, we assume that 1 -methyl-4,4'-bi-pyridinium bromide is "activated" by a yet unknown light reaction. 
  Reference    Z. Naturforsch. 35c, 770—775 (1980); received May 23/June 6 1980 
  Published    1980 
  Keywords    Superoxide, Lipid Peroxidation, Ethane, Chloroplasts, Pyridinium Salts 
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 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-0770.pdf 
 Identifier    ZNC-1980-35c-0770 
 Volume    35 
2Author    RichardJ. Youngman, AlanD. DodgeRequires cookie*
 Title    Mechanism of Paraquat Action: Inhibition of the Herbicidal Effect by a Copper Chelate with Superoxide Dismutating Activity  
 Abstract    The treatment of flax cotyledons (Linum usitatissimum) with paraquat was shown to decrease the levels of chlorophyll and carotenoid pigments. The fatty acid content of chloroplast fragments isolated from treated tissue was determined and shown to be greatly decreased by paraquat treat­ ment. The superoxide radical was demonstrated to play an important role in the phytotoxic action of paraquat by the use of a copper chelate of D-penicillamine, which has a high superoxide dismutat­ ing activity. The action of paraquat was inhibited by this compound. The role of superoxide is discussed with reference to the generation of more toxic species, such as singlet oxygen. 
  Reference    Z. Naturforsch. 34c, 1032—1035 (1979); received May 26 1979 
  Published    1979 
  Keywords    Paraquat, Plant Pigments, Fatty Acids, Superoxide, Copper Chelate, Flax Cotyledons 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-1032.pdf 
 Identifier    ZNC-1979-34c-1032 
 Volume    34 
3Author    EvaP. Aur, RichardJ Y Oungm An, E. Dm, L. En, G. Feld Er, ErichF E LstnerRequires cookie*
 Title    Mechanisms of Adriamycin-Dependent Oxygen Activation Catalyzed by NADPH-Cytochrome c*-(Ferredoxin)-Oxidoreductase  
 Abstract    Under aerobic conditions, 0 2 uptake and production o f 0 2~ and H 20 2 by isolated N A D P H -cytochrome c-(ferredoxin)-oxidoreductase from Euglena gracilis was strongly stim ulated by adriamycin. Further stim ulation was not observed with 0.1 m M F e 3+-EDTA. M ethionine fragmentation (measured as ethylene release), as a reliable indicator for the formation o f O H ' radical-like oxidants under aerobic conditions (1 0 0 |im o l 0 2 in a 10 ml reaction vessel) was strongly stimulated by 0.1 m M F e3+-ED TA or, in the absence o f iron, by partial anaerobiosis (1 (irnol 0 2 per vessel). The highest rate o f m ethionine fragm entation was observed under an­ aerobic conditions in the presence o f both reduced adriam ycin and added H 20 2. Aerobic methionine fragmentation in the presence o f adriam ycin and F e3+-ED TA was inhibited by superoxide dismutase and catalase by m ore than 90%, w hile m ethionine fragmen­ tation under semianaerobiosis in the absence o f F e 3+-E D T A was inhibited by superoxide dismutase to only about 50%, while catalase again inhibited by m ore than 90%. These results indicate that the adriamycin-catalyzed production o f a strong oxidant appears to be governed by different mechanisms depending on oxygen availability; nam ely the production o f a Fenton-type oxidant driven by adriamycin-catalyzed superoxide form ation and also, the formation o f the "crypto-OH' radical" by direct electron donation from the adriam ycin sem iquinone radical to H20 2 under oxygen limiting conditions. 
  Reference    Z. Naturforsch. 39c, 261—267 (1984); received D ecem ber 15 1983 
  Published    1984 
  Keywords    Adriamycin, Oxygen Activation, Oxygen Toxicity, Superoxide, H ydroxyl Radical 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0261.pdf 
 Identifier    ZNC-1984-39c-0261 
 Volume    39