Barrows L R, Magee P N
Carcinogenesis. 1982;3(3):349-51. doi: 10.1093/carcin/3.3.349.
S-Adenosylmethionine was found to methylate DNA non-enzymatically to produce the same putative promutagenic and procarcinogenic lesions formed by carcinogenic chemical methylating agents. The formation of 7-methylguanine was confirmed by u.v. spectrophotometry, the formation of O6-methylguanine and 3-methyladenine was suggested by the cochromatography of radioactivity with standard bases. It is possible that this reaction may explain the presence of constitutive cellular enzymes specifically for the repair of methylated DNA, and may indicate the mechanism whereby methylated guanine is formed in the liver DNA of rats with chemically induced liver damage.
已发现S-腺苷甲硫氨酸可非酶促地使DNA甲基化，产生与致癌化学甲基化剂形成的相同的假定促突变和致癌前病变。通过紫外分光光度法证实了7-甲基鸟嘌呤的形成，通过放射性与标准碱基的共色谱法提示了O6-甲基鸟嘌呤和3-甲基腺嘌呤的形成。这种反应有可能解释专门用于修复甲基化DNA的组成型细胞酶的存在，并可能表明在化学诱导肝损伤的大鼠肝脏DNA中形成甲基化鸟嘌呤的机制。
