The Application of Rapid Lysis Techniques in Radiobiology: III. The Effect of Radiosensitizers on the Production of DNA Damage and the Time Course of Its Repair

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Abstract
P-Nitroacetophenone (PNAP) increases the yield of single-strand breaks (ssb) measured 0.2 s after irradiation of Escherichia coli B/r to the same extent as does O2. Norpseudopelletierine-N-oxyl (NPPN) does not modify the yield of ssb seen. By studying the time course of the enzymatic repair of ssb and DNA fixed damage with E. coli B/r and K12 Pol A1- it was shown that neither PNAP or NPPN enhanced the yield of fixed damage of the type produced by O2. Repair of radiation-produced ssb in the NPPN experiments was inhibited so that after about 120 s the yield of ssb was the same as was found with PNAP or O2. PNAP can apparently only mimic one of the effects of O2 on DNA damage and that NPPN modifies DNA damage in a different manner to O2.