Mechanisms for radiation damage in DNA. Progress report, January 1, 1982-December 31, 1982

In this project several mechanisms are proposed for radiation damage to DNA constituents and DNA, and a series of experiments utilizing electron spin resonance spectrometry to test the proposed mechanisms have been detailed. In the past studies have concentrated chiefly on the direct effect of radiation on DNA. We are currently investigating irradiated systems of DNA constituents which may shed light on indirect effects. In addition, studies of radiation effects on lipids have been undertaken which will shed light on the only other proposed site for cell kill, the membrane. Studies which we have completed during this year are: (1) ESR Study of Radicals Produced by One Electron Loss from 6-Azauracil, 6-Azathymine and 6-Azacytosine: Evidence for Both sigma and ..pi..-Radicals; (2) Hydrogen Abstraction Reactions by Amide Electron Adducts: A Comparison to Acid, Ester, Aldehyde and Ketone Electron Adducts. Studies which we have made progress on are: (3) An ESR and INDO Study of the ..pi..-Cations of 5-Hydroxymethyl-uracil and 5-Hydroxymethyl-cytosine: Evidence for Intramolecular Hydrogen Bonding; (4) Studies of the ..pi..-Cations of 5-Halouracils and 5-Halocytosines; (5) Studies of Radiation Damage to Lipids