ANALYSIS AND EXCISION OF RING-OPENED PHOSPHORAMIDE MUSTARD-DEOXYGUANINE ADDUCTS IN DNA

  • 1 January 1982
    • journal article
    • research article
    • Vol. 42  (7) , 2616-2621
Abstract
The reaction products formed by reacting deoxyguanosine with phosphoramide mustard at pH 7.4 were analyzed by high-performance liquid chromatography and Schiff''s reaction. The adducts consisted of 5 fractions of phosphoramide mustard-imidazole ring-opened deoxyguanosine complexes and 1 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 [Bacillus subtilis] 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 [Escherichia coli] formamidopyrimidine-DNA glycosylase was precluded by the limitations of this assay system, which requires that any 2 ring-opened guanines cross-linked by phosphoramide mustard be both excised to be detected.

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