title: Human lymphoblasts contain DNA glycosylase activity excising N-3 and N-7 methyl and ethyl purines but not O6-alkylguanines or 1-alkyladenines.
abstract: Cultured human lymphoblasts (CCRF-CEM line) have DNA glycosylase activities, the specificities of which were investigated by using high-performance liquid chromatography. In addition to 3-methyladenine, 3-ethyladenine, 7-methylguanine, 7-ethylguanine, 3-methylguanine, and 3-ethylguanine also were excised from alkylated double-stranded DNA and deoxypolynucleotides, but 1-methyladenine, 1-ethyladenine, O6-methylguanine, and O6-ethylguanine were not. The glycosylase activity was generally greater for the methylated than for the corresponding ethylated purines and was also greater toward 3-alkyladenine than toward 3-alkyladenine than toward 3-alkylguanine. 7-Methylguanine and 7-ethylguanine were excised to similar but low extents. However, in molar terms, the release of 7-methylguanine was similar to that of 3-methyladenine.
mesh_terms: D000478:Alkylation; D000818:Animals; D002417:Cattle; D004247:DNA / Q000378:metabolism; D045647:DNA Glycosylases; D006801:Humans; D008214:Lymphocytes / Q000201:enzymology*; D008745:Methylation; D009699:N-Glycosyl Hydrolases / Q000378:metabolism*; D011089:Polydeoxyribonucleotides; D011687:Purines / Q000032:analysis*; D013379:Substrate Specificity; D013950:Thymus Gland
chemical_list: D011089:Polydeoxyribonucleotides; D011687:Purines; D004247:DNA; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; C076131:DNA-3-methyladenine glycosidase II