Radical ions and their reactions in DNA constituents: ESR/ENDOR studies of radiation damage in the solid state.

This updating review contains the results of recent ESR/ENDOR experiments on DNA constituents in the solid state. The compounds reviewed include single crystals of the DNA bases, nucleosides, and nucleotides. The emphasis is on low-temperature ENDOR results. Typical experiments involve irradiations at or near helium temperatures in attempts to determine the primary radiation-induced oxidation and reduction products. The use of the ENDOR technique allows one to determine the protonation state of the initial products. Subsequent warming of the sample facilitates a study of the reactions that these primary products undergo. A critical review of previous ESR experiments is considered to see if these results conflict with the newer ENDOR results. Finally, a summary is provided to show which of the numerous results discussed may have some relevance to understanding the radiation chemistry of DNA.