Buonarati M H, Turteltaub K W, Shen N H, Felton J S
Biomedical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94550.
Mutat Res. 1990 Nov;245(3):185-90. doi: 10.1016/0165-7992(90)90048-o.
Mutagenic activity associated with amino-imidazoazaarene food-derived mutagens such as 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) appears to be dependent upon N-hydroxylation, though additional metabolic pathways may be involved in the production of the ultimate reactive intermediate which covalently binds DNA. We have evaluated the ability of 2-hydroxyamino-1-methyl-6-phenylimidazo[4,5-b]pyridine (N-hydroxy-PhIP) to bind DNA in vitro and have determined which secondary metabolic pathways are involved in the production of electrophilic intermediates. Incubation of DNA with 10 microM N-hydroxy-PhIP alone or with mouse-liver cytosol did not result in detectable adduct formation. Addition of 3'-phosphoadenosine 5'-phosphosulfate or acetyl coenzyme A to cytosolic incubations containing N-hydroxy-PhIP resulted in DNA adducts which could be detected by 32P-postlabeling at levels of 594 and 30 fmoles/micrograms DNA, respectively. Addition of 3'-phosphoadenosine 5'-phosphosulfate and to a lesser extent acetyl coenzyme A to cytosolic incubations also increased the rate of degradation of the unstable N-hydroxy-PhIP intermediate. These data suggest that both sulfation- and acetylation-dependent metabolic pathways may be important in the mammalian genotoxic actions of PhIP.
与氨基咪唑氮杂芳烃类食物诱变剂（如2-氨基-1-甲基-6-苯基咪唑并[4,5-b]吡啶，简称PhIP）相关的诱变活性似乎取决于N-羟基化作用，不过在产生与DNA共价结合的最终反应性中间体的过程中可能还涉及其他代谢途径。我们评估了2-羟基氨基-1-甲基-6-苯基咪唑并[4,5-b]吡啶（N-羟基-PhIP）在体外与DNA结合的能力，并确定了哪些次级代谢途径参与了亲电中间体的产生。单独将DNA与10微摩尔的N-羟基-PhIP孵育，或与小鼠肝脏胞液一起孵育，均未导致可检测到的加合物形成。在含有N-羟基-PhIP的胞液孵育体系中添加3'-磷酸腺苷5'-磷酸硫酸酯或乙酰辅酶A，会导致形成DNA加合物，通过32P后标记法可分别检测到加合物水平为594和30飞摩尔/微克DNA。在胞液孵育体系中添加3'-磷酸腺苷5'-磷酸硫酸酯以及在较小程度上添加乙酰辅酶A，也会加快不稳定的N-羟基-PhIP中间体的降解速率。这些数据表明，硫酸化和乙酰化依赖的代谢途径在PhIP的哺乳动物遗传毒性作用中可能都很重要。
