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'Pulse Radiolysis' in keywords Facet   section ZfN Section C  [X]
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1982 (1)
1979 (1)
1Author    E. Lengfelder, E. F. ElstnerRequires cookie*
 Title    Cyanide Insensitive Iron Superoxide Dismutase in Euglena gracilis Comparison of the Reliabilities of Different Test Systems for Superoxide Dismutases  
 Abstract    Two proteins (Px and P2 , with mol weights of 57,500 and 27,500, respectively) were isolated from Euglena gracilis. Both proteins show cyanide-insensitive superoxide dismutase activity in the "classical" superoxide dismutase assay, using xanthine-xanthine oxidase as 0 2 ~ generator. If 0 2'~ is generated chemically (autoxidation of reduced anthraquinone), photochemically (illuminated riboflavine) or pulse radiolytically, only protein Pt but not P2 shows SOD activity. Protein P t contains l g atom (determined: 0.82) iron (no Mn or Cu) per mole protein and may thus be defined as iron-superoxide dismutase. Protein P2 , showing the spectral properties of a flavoprotein, exhibits the activities of ferredoxin-NADP-oxidoreductase and "diaphorase". The cyanide-insensi-tive SOD-activity of this "diaphorase" in the xanthine oxidase-assay for superoxide dismutase makes this classical and commonly used test unreliable for assaying cyanide insensitive SOD activities. The existence of the "prokaryote-type" of superoxide dismutase (Fe-SOD) in Euglena gracilis is exceptional for an eukaryotic, autotrophically grown organisms. 
  Reference    Z. Naturforsch. 34c, 374 (1979); received February 9 1979 
  Published    1979 
  Keywords    Fe-Superoxide Dismutase, Superoxide Dismutase Test Systems, E uglena gracilis, Pulse Radiolysis 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-0374.pdf 
 Identifier    ZNC-1979-34c-0374 
 Volume    34 
2Author    Z. NaturforschRequires cookie*
 Title    Über die oxidative Hauptkettenspaltung einiger Nukleinsäuren — Pulsradiolytische Untersuchungen  
 Abstract    O n the O xidative M ain-C hain Scission o f N u cleic A cids — P ulse R adiolysis S tudies O tm ar D enk und W olfram Schnabel Polyriboadenylic acid, polyribocytidylic acid and polyribouridylic acid were irradiated with 16 MeV electrons in aqueous solution. Part of the OH radicals generated during the radiolysis of water reacted with the sugar moieties of the polynucleotides. Subsequently formed peroxyl radicals reacted with each other thus forming oxyl radicals whose's decay led to main-chain scissions with the consequence of a decrease of the light scattering intensity (LSI). In the case of single-stranded polynucleotides, the analysis of the LSI decay curves revealed the occurrence of two processes. The rapid mode was assigned to the intramolecular and the slow mode to the intermolecular reaction of peroxyl radicals. For the rate constant of the rapid process (activation energy: 5 kcal/mol) a pronounced kinetic salt effect was observed. In the case of double-stranded polynucleotides (polyA and polyC at pH 4, poly(A+U) at pH 8) the same effects were observed as with native calf thymus DNA in a former study [9]: The LSI decreased only after a critical dose was surpassed. A rapid process was followed by a slow one. The slow process is assigned to the melting of H-bridges located at bases between main-chain scissons in the double helix. The rapid process corresponds to the separation of fragments formed by two single strand breaks laying very close to each other on opposite sites in the double helix. 
  Reference    Z. Naturforsch. 37c, 405—412 (1982); received February 1/M arch 16 1982 
  Published    1982 
  Keywords    Nucleic Acids, Main-Chain Scission, Peroxyl Radicals, Intra-and Intermolecular Reactions, Pulse Radiolysis 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-0405.pdf 
 Identifier    ZNC-1982-37c-0405 
 Volume    37