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'Irradiation' in keywords Facet   section ZfN Section C  [X]
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1977 (1)
1Author    F. Ojeda, M. Flores, H. FolchRequires cookie*
 Abstract    The effect o f irradiation on the anti Ig binding ability o f lymphocytes after irradiation was studied. Norm al control and irradiated lym phoid cells were treated with rabbit anti mouse IgG fluorescein conjugated serum and the fluores­ cein positive cells compared. A reduction in the proportion o f stained cells in the irradiated lym phocytes was found. It depends on the dose and on the incubation tim e at 37 °C after irradiation. The m axim um effect was detected after 10 minutes o f incubation, longer incubation is associated with a partial recovery o f the stainability o f the IgG recep­ tors. 
  Reference    Z. Naturforsch. 34c, 888 (1979); received January 30 1979 
  Published    1979 
  Keywords    Lymphocytes, Receptors, Irradiation 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-0888_n.pdf 
 Identifier    ZNC-1979-34c-0888_n 
 Volume    34 
2Author    Brigitte Kiefer, LaskeRequires cookie*
 Title    Jürgen  
 Abstract    Protein synthesis after UV-and X-irradiation was investigated in diploid yeast. The incorpora­ tion of radioactively labelled lysine and phenylalanine was measured 2.5 and 4 hours after ex­ posure. By varying the specific activity the pool sizes could be estimated. At 2.5 hours there is some increase in pool sizes and a dose-dependent enhancement of protein synthesis. At 4 hours pools are again normal, but the increase of synthetic activity prevails. 
  Reference    (Z. Naturforsch. 32c, 973 [1977]; received August 29 1977) 
  Published    1977 
  Keywords    Yeast, Protein Synthesis, Amino Acid Pools, Irradiation 
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 TEI-XML for    default:Reihe_C/32/ZNC-1977-32c-0973.pdf 
 Identifier    ZNC-1977-32c-0973 
 Volume    32 
3Author    Vera Jakubick, Henry DelincéeRequires cookie*
 Title    Strahleninduzierte Aggregatbildung von Proteinen: Bindung von Aminosäuren an Myoglobin Radiation-Induced Aggregation of Proteins: Binding of Amino Acids to Myoglobin  
 Abstract    When myoglobin is irradiated in the presence of amino acids, the most radiation-reactive species, like the aromatic and sulfur-containing amino acids, will bind preferentially to the protein. The radiation-induced binding is strongly dependent on the concentration of protein and amino acid. Subsequent to irradiation of myoglobin in the presence of radioactively labelled tryptophan followed by tryptic hydrolysis, only a single radioactive spot was detected on the fingerprint. The binding of amino acids is thus not randomly distributed over the protein molecule but occurs at specific reactive sites. 
  Reference    Z. Naturforsch. 33c, 203—209 (1978); eingegangen am 23. September 1977/27. Januar 1978 
  Published    1978 
  Keywords    Irradiation, Protein Aggregation, Myoglobin, Amino Acids, Specific Binding 
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 TEI-XML for    default:Reihe_C/33/ZNC-1978-33c-0203.pdf 
 Identifier    ZNC-1978-33c-0203 
 Volume    33 
4Author    Eberhard Bothe, D. Ietrich Schulte-FrohlindeRequires cookie*
 Title    Release of K+ and H+ from Poly U in Aqueous Solution upon y and Electron Irradiation. Rate of Strand Break Formation in Poly U  
 Abstract    Conductivity changes were found which followed the reaction of radiolytically generated OH radicals with the potassium salt of polyuridylic acid (poly U) in aqueous solution. After 60Co-y-irradiation the observed increase of conductivity at pH = 6.8 was shown to consist of the liberation of K+ ions from the stock of K+ ions electrostatically bound to the polyanion. The initial G(K+) is 36 and hence 6 times higher than the G value of OH radicals in N20 saturated solutions. At a poly U concentration of 60 mg I-1 half of the ion release occurred at 12 J kg-1 and nearly all ions are released at 40 J kg-1. The liberation of K+ is explained to be a consequence of the formation of chain breaks leading to an increase of the degree of dissociation. The rate of the ion release was studied under pulse radiolysis conditions. Because of the high G-vlaue of counterion liberation and the use of conductivity as analytical quantity the method is very sensitive. With 6 mg I-1 poly U the rate could be measured even at a dose per pulse of 0.25 J kg-1. The kinetics of the ion release can be described in terms of two parallel first order reactions of comparable contribution with an average rate constant of 0.8 s-i at 20 °C, 60 mg l-1 poly U and pH = 6.8 with a small contribution of slower components. In more acidic solutions, besides K+ ions H+ are also liberated since at low pH values bound K+ is replaced by H+. The rate of the ion release was found to increase with increasing replacement of K+ by H+ (^?bs = 100 s-1 at pH = 3.4, 60 mg I-1 poly U and T = 18 °C). With potassium ion free poly­ uridylic acid the corresponding rate constant amounted to 220 s_1, nearly independent of pH. From the temperature dependence activation parameters for the ion release were derived (£ a = 57 kJ mol-1, A = 1.0 x 1010 s— 1 at pH = 6.8). Addition of p-benzoquinone at pH = 3.7 and dithiothreitol (DTT) at pH 6.8 were found to decrease the size of the conductivity changes and to increase the rate. The results show that p-benzoquinone and DTT react with poly U radicals and that these reactions prevent chain breaks and ion liberation. It is concluded that the rate determining step of the conductivity increase is the formation of strand breaks by a cleavage of poly U radicals and that this reaction is pH dependent. The pH dependence and the observed value for the activation energy was found to be in agreement with the behaviour of a model system for the earlier postulated C-4' mechanism for strand break formation of polynucleotides and DNA. 
  Reference    Z. Naturforsch. 37c, 1191—1204 (1982); received July 5 1982 
  Published    1982 
  Keywords    Polyuridylic Acid, Irradiation, Conductivity, Strand Break, Rate 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-1191.pdf 
 Identifier    ZNC-1982-37c-1191 
 Volume    37