Mechanisms for radiation damage in DNA. Progress report, January 1, 1981-December 31, 1981

Several mechanisms for radiation damage to DNA constituents and DNA are proposed, and a series of experiments utilizing electron spin resonance spectrometry to test the proposed mechanisms is detailed. Past experiments have concentrated chiefly on the direct affect of radiation on DNA. Currently irradiated systems on DNA constituents are being investigated to shed light on indirect effects. In addition, studies of radiation effects on lipids were undertaken which will shed light on the only other proposed site for cell kill, the membrane. Studies which were completed or progressed during the past year include: (1) study of the oxidation radicals in azauracil and azathymine: a case for both sigma and π radicals; (2) studies of the π-cation radicals of the 5-halouracils; (3) hydrogen abstraction reactions by the peptide bond protonated anion: a comparison to acid, ester, aldehyde, and ketone protonated anions; (4) internal hydrogen bonding in the π-cations of hydroxymethyluracil and hydroxymethyl-cytosine; and (5) study of radicals generated in model compounds for the sugar-phosphate backbone