Chin D H, Carr S A, Goldberg I H
J Biol Chem. 1984 Aug 25;259(16):9975-8.
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.
新制癌菌素发色团对DNA的链断裂作用可将脱氧核糖的5'-羟基转化为5'-醛基。醛基氧的来源现已通过质谱分析得以阐明。在2H218O/16O2或2H216O/18O2中用新制癌菌素发色团处理DNA所产生的与DNA相关的胸苷5'-醛基，经还原、核酸酶处理释放、全甲基化后，通过气相色谱-质谱联用仪进行分析。数据清楚地表明，分子氧是5'-醛基氧的唯一来源。C-5'处分子氧的添加，可能是通过新制癌菌素发色团的一种反应形式，必然参与其中；C-5'处的碳正离子中间体被排除。
