title: Lack of effect of glutathione on the binding of dimethylnitrosamine to DNA in vitro.
abstract: The possibility that glutathione (GSH) S-transferases may affect microsome-mediated methylation of DNA by dimethylnitrosamine (DMN) in vitro has been investigated using aflatoxin B1 (AFB1) as a positive control. Hamster liver microsomes were incubated with either [14C]DMN or [3H]AFB1 and calf thymus DNA, with or without GSH and hamster cytosol. Although a significant amount of DMN was metabolized, GSH alone or in conjunction with cytosol or purified GSH S-transferases did not affect the binding of 14C to DNA and the amount of 7-methylguanine formed. However with AFB1, a significant reduction in both its binding to DNA and in the formation of AFB1-N7Gua adduct with a concomitant increase in AFB1-GSH conjugation was observed, suggesting that the test system was functioning effectively.
mesh_terms: D016604:Aflatoxin B1; D000348:Aflatoxins; D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D006224:Cricetinae; D004247:DNA; D004249:DNA Damage; D004128:Dimethylnitrosamine / Q000378:metabolism*; D005978:Glutathione / Q000494:pharmacology*; D006147:Guanine; D066298:In Vitro Techniques; D008745:Methylation; D008862:Microsomes, Liver / Q000378:metabolism
chemical_list: D000348:Aflatoxins; D006147:Guanine; D004247:DNA; D016604:Aflatoxin B1; D005978:Glutathione; D004128:Dimethylnitrosamine