Detection of O6-Methyldeoxyguanosine in Human Placental DNA

摘要

A monoclonal antibody specific for O(sup 6)-methyldeoxyguanosine (O(sup 6)-MedGuo) was developed. When used in a competitive ELISA, 50% inhibition of binding was achieved with 0.51 pmol O(sup 6)-MedGuo. When the competitive ELISA was coupled with HPLC, 2 mg of DNA could be analyzed giving a lower limit of detection of 0.5 micromol O(sup 6)-MedGuo per mol deoxyguanosine. The assay was used to test for O(sup 6)-MedGuo in DNA from placentas of smoking and non-smoking women. Two of 10 DNA samples from smoking women and 3 of 10 from non-smoking women had detectable levels of O(sup 6)-MedGuo. Levels ranged from 0.6 to 1.6 micromol O(sup 6)-MedGuo per mol deoxyguanosine. Levels of O(sup 6)-alkylguanine DNA alkyltransferase (AAT) protein were also measured. There was no apparent relationship between AAT and O(sup 6)-MedGuo levels in the 20 subjects, nor did mean AAT levels differ between the 2 groups. Although no apparent relationship between smoking history and O(sup 6)-MedGuo formation was found in the preliminary study, the report is the first of a structurally identified DNA adduct in human placenta.