The action of ionizing radiation on DNA in the presence of quinacrine. II. DNA strand breakage.

Strand breakage of DNA irradiated in solution and in the dry state in the presence of quinacrine was investigated by sedimentation analysis. Determination of single strand breaks in solution combined with binding studies permits to conclude that bound quinacrine protects DNA more effectively than the free compound. In the dry state quinacrine is without detectable effect on both single and double strand break formation, neither under aerobic nor anaerobic conditions.