Photosensitized reactions in nucleic acids: Photosensitized formation and splitting of pyrimidine dimers

Abstract

Summary Photosensitized reactions in nucleic acids can be used either to create a selective lesion or to remove U.V.-induced damages. The formation of pyrimidine dimers in DNA can be photosensitized by aromatic ketones such as benzophenone or acetophenone. Chain breaks are also produced by reaction of radicals produced upon excitation of the ketone. Radical scavengers may prevent this latter reaction. The splitting of pyrimidine dimers can be photosensitized by indole derivatives either in fluid or frozen aqueous solutions. Splitting results from a reaction of the dimer with electrons supplied by the indole ring either directly in ground-state or excited-state complexes or via the intermediate formation of solvated electrons after photoejection by the excited indole derivative.