title: Incorporation of 18O2 into thymidine 5'-aldehyde in neocarzinostatin chromophore-damaged DNA.
abstract: Strand scission of DNA by the chromophore of neocarzinostatin converts the 5'-hydroxyl of deoxyribose to a 5'-aldehyde. The origin of the aldehydic oxygen has now been elucidated by mass spectrometry. DNA-associated thymidine 5'-aldehyde produced by treatment of DNA with neocarzinostatin chromophore in 2H218O/16O2 or in 2H216O/18O2 was reduced, liberated by nuclease treatment, permethylated, and analyzed by gas chromatography-mass spectrometry. The data clearly show that molecular oxygen is the only source of the 5'-aldehydic oxygen. The addition of molecular oxygen at C-5', possibly via a reactive form of neocarzinostatin chromophore, must be involved; a carbonium ion intermediate at C-5' is ruled out.
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic; D002417:Cattle; D055598:Chemical Phenomena; D002621:Chemistry; D004247:DNA; D003903:Deuterium; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D010100:Oxygen; D010103:Oxygen Isotopes; D013936:Thymidine / Q000031:analogs & derivatives* / Q000032:analysis; D013950:Thymus Gland; D009353:Zinostatin
chemical_list: D000903:Antibiotics, Antineoplastic; D010103:Oxygen Isotopes; C042517:thymidine-5'-aldehyde; D004247:DNA; D009353:Zinostatin; D003903:Deuterium; D010100:Oxygen; D013936:Thymidine