Pfohl-Leszkowicz A, Boiteux S, Laval J, Keith G, Dirheimer G
Biochem Biophys Res Commun. 1983 Oct 31;116(2):682-8. doi: 10.1016/0006-291x(83)90579-x.
The enzymatic methylation of chemically alkylated DNA and of poly(dG-dC) X poly(dG-dC) by beef brain DNA(cytosine-5-)-methyltransferase have been tested. The alkylation by dimethylsulfate, which yields mostly 7 methylguanine (m7G) and 3 methyladenine (m3A) do not affect the enzymatic methylation. The dimethylsulfate alkylated poly(dG-dC) X poly(dG-dC) converted into the Z-form in the presence of MgCl2, is just as well methylated as the native or the alkylated polynucleotide in the B-form. The alkylation of DNA or of poly(dG-dC) X poly(dG-dC) by methylnitrosourea yields, in addition to the above base modifications described for dimethylsulfate, methylphosphotriesters and O6-methylguanine. The enzymatic methylation of these substrates modified by methylnitrosourea is decreased. This decrease is proportional to the extent of the chemical alkylation of the substrate.
已经测试了牛肉脑DNA（胞嘧啶-5-）-甲基转移酶对化学烷基化DNA和聚（dG-dC）×聚（dG-dC）的酶促甲基化作用。硫酸二甲酯的烷基化主要产生7-甲基鸟嘌呤（m7G）和3-甲基腺嘌呤（m3A），不影响酶促甲基化。在MgCl2存在下转化为Z型的硫酸二甲酯烷基化聚（dG-dC）×聚（dG-dC），与天然或B型烷基化多核苷酸一样容易被甲基化。除了上述硫酸二甲酯描述的碱基修饰外，甲基亚硝基脲对DNA或聚（dG-dC）×聚（dG-dC）的烷基化还产生甲基磷酸三酯和O6-甲基鸟嘌呤。甲基亚硝基脲修饰的这些底物的酶促甲基化作用降低。这种降低与底物的化学烷基化程度成正比。
