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1992 (1)
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1Author    Y. A. Belyaev, Y. Evgeny, D. A. Lipov, V. Ictor, S. Shcheglov, VitalyN. LystsovRequires cookie*
 Title    Resonance Effect of Microwaves on the Genome Conformational State of E. coli Cells  
 Abstract    The effect of low intensity microwaves on the conformational state o f the genome of X-irradiated E. coli cells was studied by the method of viscosity anomalous time dependencies. It has been established that within the ranges of 51.62-51.84 GHz and 41.25-41.50 GHz the frequency dependence of the observed effect has a resonance nature with a resonance half­ width of the order of 100 MHz. The power dependence of the microwave effect within the range of 0.1 -2 0 0 (iW/cm2 has shown that a power density of 1 nW/cm2 is sufficient to suppress radiation-induced repair of the genome conformational state. The effect of microwave sup­ pression of repair is well reproduced and does not depend on the sequence of cell exposure to X-rays and microwave radiation in the millimeter band. The results obtained indicate the role o f the cell genome in the resonant interaction of cells with low intensity millimeter waves. 
  Reference    Z. Naturforsch. 47c, 621—627 (1992); received September 21 1990/January 1 1992 
  Published    1992 
  Keywords    Cellular Biology, Microwave Bioaction, Radiation Damage, Repair 
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 TEI-XML for    default:Reihe_C/47/ZNC-1992-47c-0621.pdf 
 Identifier    ZNC-1992-47c-0621 
 Volume    47 
2Author    U. P. FringeliRequires cookie*
  Reference    (Z. Naturforsch. 31c, 746 [1976]; received August 17 1976) 
  Published    1976 
  Keywords    Electron Microscopy, Radiation Damage, Polypeptide Monolayers, Infrared Dichroism, Conformational Changes 
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 TEI-XML for    default:Reihe_C/31/ZNC-1976-31c-0746_n.pdf 
 Identifier    ZNC-1976-31c-0746_n 
 Volume    31 
3Author    H. Elm, Ut Durchschlag, Peter ZipperRequires cookie*
 Title    Electrophoretic and Chemical Studies on the X-Ray Damage of Malate Synthase  
 Abstract    The sulfhydryl enzyme malate synthase was shown to undergo an X-ray induced aggregation and inactivation in solution (Zipper and Durchschlag, Radiat. Environ. Biophys. 18, 99-121 (1980)). Further evidence for the occurrence o f aggregation and inactivation and also of fragmen­ tation and partial unfolding of the enzyme upon X-irradiation was obtained by chemical and electrophoretic studies. Irradiation was carried out in a specially designed microcell, experiments were performed on the microlevel. Under conditions o f the experiments the formation of H20 2 upon X-irradiation could be proven; therefore the influence of H20 2 on the enzyme was investigated too. Though the quantitative results o f the damaged enzyme particles are influenced by many disturbing factors, the findings allow clear statements on the nature of the effects under investigation. 1) Both X-irradiation and treatment with H20 2 caused a decrease of total and an increase o f available sulfhydryl groups o f the enzyme and led to a loss o f enzymic activity. The presence o f dithiothreitol turned out to be able to protect the enzyme against X-ray or H20 2 induced inactivation. Moreover, addition of dithiothreitol after X-irradiation or H20 2 treatment allowed a considerable repair o f enzymic activity. 2) Polyacrylamide gel disc electrophoreses o f X-irradiated enzyme solutions, performed in the presence of sodium dodecyl sulfate, showed the occurrence o f covalently cross-linked subunits (preferably dimers and trimers) and of various definite fragments. Electrophoreses in the absence of the denaturant indicated the occurrence o f enzyme aggregation. The effects were more pronounced with increasing X-ray doses. The electrophoreses also clearly reflected a radioprotec­ tion by dithiothreitol against cross-linking, but not against fragmentation. Addition o f excess of 2-mercaptoethanol or of dithiothreitol to the X-irradiated enzyme clearly demonstrated that part of the covalent cross-links were disulfide bridges; the aggregates themselves, however, were held together primarily by non-covalent bonds. Blocking of exposed enzyme sulfhydryls by means of Ellman's reagent prevented both covalent cross-linking and enzyme aggregation. 3) Similar electrophoretic patterns as found for the X-irradiated enzyme were obtained for the unirradiated enzyme after treatment with H 20 ?. The similarity o f the electropherograms, as well as the reversible diminution o f enzymic activity and the loss o f sulfhydryls in the presence of H20 2, suggest an involvement o f H20 2 in the radiation damage o f the enzyme. It seems plausible that oxidation reactions are responsible for the effects caused by X-irradiation or H20 2 treatment. 
  Reference    Z. Naturforsch. 36c, 516—533 (1981); received November 12 1979/February 4 1981 
  Published    1981 
  Keywords    Malate Synthase, Radiation Damage, PAGE, Protection and Repair by Dithiothreitol, Effects of Hydrogen Peroxide 
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 TEI-XML for    default:Reihe_C/36/ZNC-1981-36c-0516.pdf 
 Identifier    ZNC-1981-36c-0516 
 Volume    36