title: Methylation of DNA in rat liver and intestine by dimethylnitrosamine and N-methylnitrosourea.
abstract: A chromatographic procedure for improved separation of deoxyribonucleosides and methylated deoxyribonucleosides is described. DNA was isolated from liver and small intestine of rats treated with [14C]dimethylnitrosamine ([14C]DMN) or N-[3H]methyl-N-nitrosourea ([3H]MNU), and the purified DNA was hydrolyzed enzymatically. The deoxyribonucleosides were chromatographed on an Aminex A-6 cation exchange column at 37 degrees C with 0.4 M ammonium formate, pH 4.5, as eluant. In addition to showing the presence of the expected alkylated products, N7-methyldeoxyguanosine (determined as N7-methylguanine) and O6-methyldeoxyguanosine, several other minor methylated products were found in liver and intestinal DNA of rats treated with DMN or MNU. Two of these products are believed to be N3-methylthymidine and O4-methylthymidine.
mesh_terms: D000818:Animals; D004247:DNA / Q000378:metabolism*; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism*; D003854:Deoxyribonucleotides / Q000032:analysis; D004128:Dimethylnitrosamine / Q000378:metabolism*; D007421:Intestine, Small / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008770:Methylnitrosourea / Q000378:metabolism*; D008780:Methyltransferases / Q000378:metabolism*; D009602:Nitrosamines / Q000378:metabolism*; D009607:Nitrosourea Compounds / Q000378:metabolism*; D009963:Orotic Acid / Q000378:metabolism; D051381:Rats
chemical_list: D003854:Deoxyribonucleotides; D009602:Nitrosamines; D009607:Nitrosourea Compounds; D009963:Orotic Acid; D008770:Methylnitrosourea; D004247:DNA; D008780:Methyltransferases; D004248:DNA (Cytosine-5-)-Methyltransferases; D004128:Dimethylnitrosamine