Abstract
Hahn-Meitner-Institut Berlin, Bereich Strahlenchemie, Glienicker Str. 100, 1000 Berlin 39, Fed. Rep. Germany
Penicillamine thiyl radicals, PenS', are shown to abstract hydrogen atoms from 2-propanol and to establish an equilibrium
PenS' + (CH1)2 CHOH ↔ PenSH + (CH3)2 COH.
The rate constants for the forward and back reaction have been determined to (1.4 ± 0.3) × 104 and (1.2 ± 0.3) × 108 M-1 s-1, respectively, by means of pulse radiolysis. The data have been obtained from various independent methods which include direct measurements and competitive schemes involving irreversible interception of the alcohol radical by electron acceptors (e.g. CCl4. PNAP) and/or the thiyl radical by antioxidants (e.g. α-tocopherol). The results demonstrate that the reaction of carbon-centered radicals with thiols, in radiation biology commonly known as “repair” reaction, may be reversed and thus imply the possibility of thiyl radical induced biological damage.