Craddock V M, Henderson A R
Carcinogenesis. 1982;3(7):747-50. doi: 10.1093/carcin/3.7.747.
3-Methyladenine is one of the major products formed by reaction of a large number of environmental methylating agents with DNA in vivo and in vitro. In spite of the rapid spontaneous depurination of this base an enzyme, 3-methyladenine DNA glycosylase, has been shown to catalyse its excision. The relevance of this enzyme in carcinogenesis induced by alkylating agents was studied. Acute or chronic treatment of rats with diethylnitrosamine or with N-acetylaminofluorene caused a slight increase in glycosylase activity in liver. Experiments with liver regenerating after partial hepatectomy showed a similar increase to occur at the time of DNA replication. It could be that the increase found after treatment with carcinogens was related to the accompanying increase in cell replication, rather than being the result of a specific induction by the carcinogen. Glycosylase activity was found to be higher in the liver of the rabbit and cat than in rat or hamster liver. Organ differences (liver, kidney and brain of the rabbit) were smaller than the species differences found for enzyme activity in liver.
3-甲基腺嘌呤是大量环境甲基化剂在体内和体外与DNA反应形成的主要产物之一。尽管该碱基会迅速自发脱嘌呤，但一种名为3-甲基腺嘌呤DNA糖基化酶的酶已被证明能催化其切除。对该酶在烷基化剂诱导的致癌作用中的相关性进行了研究。用二乙基亚硝胺或N-乙酰氨基芴对大鼠进行急性或慢性处理后，肝脏中的糖基化酶活性略有增加。部分肝切除术后肝脏再生的实验表明，在DNA复制时也会出现类似的增加。可能在用致癌物处理后发现的增加与伴随的细胞复制增加有关，而不是致癌物特异性诱导的结果。发现兔和猫肝脏中的糖基化酶活性高于大鼠或仓鼠肝脏。器官差异（兔的肝脏、肾脏和大脑）小于肝脏中酶活性的物种差异。
