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'G values' in keywords Facet   Publication Year 1978  [X]
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1Author    Alfred Hissung, Clemens Von SonntagRequires cookie*
 Title    Radiolysis of Cytosine, 5-Methyl Cytosine and 2'-Deoxycytidine in Deoxygenated Aqueous Solution A Pulse Spectroscopic and Pulse Conductometric Study of the OH Adduct  
 Abstract    Using the pulse radiolysis technique the OH adducts of cytosine, 5-methyl cytosine and 2'-deoxycytidine were investigated in alkaline N20 saturated aqueous solutions. Ab-sorption spectra were recorded and their change with time was correlated with the change in conductivity. An OH -induced reaction (1.4 • 10 8 1 • mol -1 • s -1) was observed with OH adducts of cytosine and 5-methyl cytosine leading to radicals (pK = 10.3), the G-values of which were 3.2 and 1.6 respectively (conductivity measurements). These intermediates were assigned to the C-5 OH radical adducts. After completion of the free radical reactions (2k = 6 • 10 8 1 • mol -1 • s -1) the resulting product mixture showed pK-values of 8.3 (cytosine, G = 0.6), 10.5 (5-methyl cytosine, G = 0.8), 10.7 (cytosine, G=1.5; 2'-deoxycytidine, G=1.5) and 12.4 (cytosine, no G-value, determinable with optical detection). Ammonia, which is a product measured after y-radiolysis of all the three compounds investigated (G(NHs) = 0.6 ± 0.1), is not released within 15 ms after the pulse. 
  Reference    Z. Naturforsch. 33b, 321—328 (1978); received November 25 1977 
  Published    1978 
  Keywords    Cytosine, G-Values, pK-Values, Absorption Spectra, Pulse Radiolysis 
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 TEI-XML for    default:Reihe_B/33/ZNB-1978-33b-0321.pdf 
 Identifier    ZNB-1978-33b-0321 
 Volume    33 
2Author    BarryJ. Parsons, Dietrich Schulte-Frohlinde, Clemens Von SonntagRequires cookie*
 Title    Reaction of Br3' 2 -with 2-Deoxy-D-ribose. A Preferred Attack at C-l  
 Abstract    In the photolysis of 5-bromouracil containing DNA Br atoms are expected inter mediates. In order to evaluate the possible site of attack of the Br atom at the sugar moiety of DNA the reaction of 2-deoxy-D-ribose with the Br atom (complexed with two bromide ions) was investigated. Hydroxyl radicals generated by the radiolysis of N20 saturated aqueous solutions were converted into Br3 -2_ radicals by 1 M bromide ions. Br3-2-reacts with 2-deoxy-D-ribose (k = 3.7 • 10 4 M -1 s -1 , pulse radiolysis). The major product is 2-deoxy-D-erythro-pentonic acid (G = 2.4, y-radiolysis). It is formed by hydrogen abstraction from C-l and oxidation of this radical by other radicals. An alternative route via the radical at C-2 is neglible. It follows that Br3-2 ~ reacts preferentially at C-l of 2-deoxy-£>-ribose. 
  Reference    Z. Naturforsch. 33b, 666—668 (1978); received March 15 1978 
  Published    1978 
  Keywords    Pulse Radiolysis, y-Radiolysis, 2-Deoxy-D-ribose, G-values, Radical Reactions 
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 TEI-XML for    default:Reihe_B/33/ZNB-1978-33b-0666.pdf 
 Identifier    ZNB-1978-33b-0666 
 Volume    33