Enhancement of radiation-induced base release from nucleosides in alkaline solution: essential role of the O.- radical.

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  • Additional Information
    • Source:
      Publisher: Taylor & Francis Country of Publication: England NLM ID: 8809243 Publication Model: Print Cited Medium: Print ISSN: 0955-3002 (Print) Linking ISSN: 09553002 NLM ISO Abbreviation: Int J Radiat Biol Subsets: MEDLINE
    • Publication Information:
      Original Publication: London ; New York : Taylor & Francis, [c1988-
    • Subject Terms:
      Nucleosides/*radiation effects; Adenosine/radiation effects ; Hydrogen-Ion Concentration ; Solutions ; Uridine/analogs & derivatives ; Uridine/radiation effects
    • Abstract:
      The effect of pH on base release in the gamma-radiolysis of N2O-saturated solutions of a number of nucleosides (including uridine, 3-methyluridine, 2',3'-O-isopropylidene-uridine, and adenosine) has been investigated. For all these nucleotides, independent of the base or sugar moiety, base release is very low at pH below 10 (G approximately (0.3-0.7) x 10(-7) mol J-1), but increases drastically to G approximately (3-4) x 10(-7) mol J-1 at pH greater than or equal to 13. This phenomenon had already been previously reported and attributed to an OH(-)-induced transfer of a base radical into a sugar radical. However, it is now shown that at pH 12, where base release starts to increase, a lowering of the dose-rate does not affect the yield of free base. The increase in base release is accompanied by an overall reduction of chromophore loss of similar magnitude (with 2',3'-O-isopropylidene-uridine and 3-methyluridine), as well as by an increase in the yield of oxidizing radicals by a factor of 2 (with uridine). The measured rate constant of the reaction of .OH/O.- with the nucleosides is also pH-dependent, as .OH reacts faster than O.- with the nucleosides by a factor of 6-7. It is concluded that the increase in base release at high pH is caused by the increasing participation of O.-, which, unlike .OH, attacks the nucleosides preferentially at their sugar moieties, and is not due to an OH(-)-induced radical transfer from the base to the sugar moiety.
    • Accession Number:
      0 (Nucleosides)
      0 (Solutions)
      2140-69-4 (3-methyluridine)
      362-43-6 (2',3'-O-isopropylidene uridine)
      K72T3FS567 (Adenosine)
      WHI7HQ7H85 (Uridine)
    • Publication Date:
      Date Created: 19920401 Date Completed: 19920602 Latest Revision: 20190907
    • Publication Date:
      20221208
    • Accession Number:
      10.1080/09553009214551191
    • Accession Number:
      1349326