Analysis and excision of ring-opened phosphoramide mustard-deoxyguanine adducts in DNA.
Analysis and excision of ring-opened phosphoramide mustard-deoxyguanine adducts in DNA.
复制标题
DNA 中开环磷酰胺芥末-脱氧鸟嘌呤加合物的分析和切除。
作者：
C. Chetsanga;G. Polidori;M. Mainwaring
用高效液相色谱法和希夫反应对脱氧鸟苷与磷酰胺芥末在pH 7.4时生成的反应产物进行了分析。加合物由5个级分的磷酰胺芥子-咪唑开环脱氧鸟苷络合物和1个完整的磷酰胺芥子-脱氧鸟苷和磷酰胺芥子-二脱氧鸟苷络合物组成。因此，与以前的观点相反，烷基鸟嘌呤的咪唑环可以在生理pH下发生分裂。希夫的反应表明，芥末开环的脱氧鸟苷加合物中的一些组分含有甲酰基，而另一些不含甲酰基。含磷酰胺芥末开环鸟嘌呤加合物的DNA用甲酰胺嘧啶DNA糖基酶处理时，有酶促脱除甲酰化开环鸟嘌呤加合物的作用。由于我们的检测系统的局限性，无法对甲酰胺并嘧啶-DNA糖基酶释放的全量开环鸟嘌呤进行定量，因为我们的检测系统要求任何两个由磷酰胺芥末交联的开环鸟嘌呤都被切除才能被检测到。
The reaction products formed by reacting deoxyguanosine with phosphoramide mustard at pH 7.4 have been analyzed by high-performance liquid chromatography and Schiff's reaction. The adducts consisted of five fractions of phosphoramide mustard-imidazole ring-opened deoxyguanosine complexes and one fraction of each of intact phosphoramide mustard-deoxyguanosine and phosphoramide mustard-dideoxyguanosine complexes. Thus, contrary to views held previously, the imidazole ring of alkylated guanine can undergo fission at physiological pH. Schiff's reaction suggests that some fractions of phosphoramide mustard-ring-opened deoxyguanosine adducts contain formyl groups, while others do not. When DNA containing phosphoramide mustard-ring-opened guanine adducts was treated with formamidopyrimidine-DNA glycosylase, there was enzymatic removal of formylated ring-opened guanine adducts. The quantification of the full amount of ring-opened guanine released by formamidopyrimidine-DNA glycosylase was precluded by the limitations of our assay system, which requires that any two ring-opened guanines cross-linked by phosphoramide mustard be both excised in order to be detected.