Methylation of hamster DNA by the carcinogen N-nitroso-bis (2-oxopropyl)amine

The alkylation of hamster liver, lung and pancreas DNA by [1-¹⁴C]- and [2,3-¹⁴C]N-nitrosobis (2-oxopropyl) amine (BOP) has been examined. The specific activity of pancreas DNA after [2,3-¹⁴C]BOP administration was only 2% of that when [1-¹⁴C]BOP was given. 7-Methylguanine, but not O-6-methylguanine, was found in hydrolysates of liver and pancreas DNA. Nearly equal amounts of alkylation were produced in the liver when [1-¹⁴C]- and [2,3-¹⁴C]BOP were given. At least one-half of the radioactivity in the liver was associated with N-alkylated purines, whereas only 20% was in this form in the pancreas.