title: Extensive photodimerization of non-adjacent pyrimidines.
abstract: In a prior study we found that non-adjacent thymidyl residues in the single-stranded alternating copolymer poly[d(G-T)] are subject to photodimerization by germicidal lamp irradiation (lambda max 254 nm). The maximum yield of this photoproduct was 1% of the total thymine of poly[d(G-T)]. We now report that dimer formation in this polymer is increased to 10 to 40% thymine as dimer between non-adjacent pyrimidines, using near-ultraviolet irradiation (lambda max 310 nm) with or without acetone triplet-sensitization. As previously observed for 254 nm irradiation, dimer formation was nearly absent in double-stranded poly[d(G-T).d(C-A)]. These observations extend prior findings by demonstrating high-yield dimerization between non-adjacent pyrimidines via direct irradiation at environmentally relevant wavelengths (greater than or equal to 280 nm), and are potentially relevant to the mechanism of the ultraviolet light-induced targeted -1 frameshift mutation.
authors.affiliation: Department of Pathology, F. E. Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799.
authors.forename: H T
authors.initials: HT
authors.lastname: Nguyen
authors.forename: K W
authors.initials: KW
authors.lastname: Minton
mesh_terms: D000096:Acetone; D004247:DNA / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D011089:Polydeoxyribonucleotides / Q000528:radiation effects; D011740:Pyrimidine Dimers; D014466:Ultraviolet Rays
chemical_list: D011089:Polydeoxyribonucleotides; D011740:Pyrimidine Dimers; D000096:Acetone; C044165:poly(d(G-T).d(C-A)); D004247:DNA