title: Glycosidic bond cleavage of thymidine by low-energy electrons.
abstract: Thymidine was exposed to low-energy electrons (LEE) as a thin solid film under a high vacuum. Nonvolatile radiation products, remaining on the irradiated surface, were analyzed by HPLC/UV and GC/MS. Here, we show that exposure of thymidine to 3-100 eV electrons gives thymine as a major product with a yield of 3.2 x 10-2 per electron (about one-third of the total decomposition of thymidine). The formation of thymine indicates that LEE induces cleavage of the glycosidic bond separating the base and sugar moieties, suggesting a nonionizing resonant process involving dissociative attachment (<15 eV). In contrast, this reaction is not very efficient by DNA base ionization and does not occur by the reaction of solvated electrons with DNA. These studies introduce a new mechanism of DNA damage involving the interaction of LEE.
authors.affiliation: Canadian Institutes of Health Research Group in the Radiation Sciences, Faculty of Medicine, University of Sherbrooke, Sherbrooke, QC, Canada J1H 5N4.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zheng
authors.forename: Pierre
authors.initials: P
authors.lastname: Cloutier
authors.forename: Darel J
authors.initials: DJ
authors.lastname: Hunting
authors.forename: J Richard
authors.initials: JR
authors.lastname: Wagner
authors.forename: Léon
authors.initials: L
authors.lastname: Sanche
mesh_terms: D002851:Chromatography, High Pressure Liquid; D004583:Electrons; D008401:Gas Chromatography-Mass Spectrometry; D006027:Glycosides / Q000737:chemistry* / Q000378:metabolism / Q000528:radiation effects*; D013056:Spectrophotometry, Ultraviolet; D013635:Tantalum / Q000737:chemistry; D013936:Thymidine / Q000737:chemistry* / Q000378:metabolism / Q000528:radiation effects*; D014618:Vacuum
chemical_list: D006027:Glycosides; D013635:Tantalum; D013936:Thymidine