Pedrali-Noy G, Weissbach A
J Biol Chem. 1986 Jun 15;261(17):7600-2.
The synthetic duplex DNA, poly(dI-dC).poly(dI-dC), is methylated in vitro by human or murine DNA methyltransferases at 20-100 times the rate of other nonmethylated DNAs. Preparation of the hemimethylated derivative, poly(dI-dMeC).poly(dI-dC), of this polymer increases its effectiveness as a substrate by 2-fold, making it 4-10 times more effective as a substrate for mammalian DNA methyltransferases than any other hemimethylated DNA so far reported. However, the apparent slower rate of de novo methylation of poly(dI-dC).poly(dI-dC) as compared to the hemimethylated derivative is due to substrate inhibition, unique to the unmethylated polymer, as the rates of de novo and maintenance methylation are identical at low substrate concentrations.
合成双链DNA，聚（dI-dC）·聚（dI-dC），在体外被人或鼠DNA甲基转移酶甲基化的速率是其他未甲基化DNA的20至100倍。制备该聚合物的半甲基化衍生物聚（dI-dMeC）·聚（dI-dC），可使其作为底物的效力提高2倍，使其作为哺乳动物DNA甲基转移酶底物的效力比迄今报道的任何其他半甲基化DNA高4至10倍。然而，与半甲基化衍生物相比，聚（dI-dC）·聚（dI-dC）从头甲基化的表观速率较慢是由于未甲基化聚合物特有的底物抑制，因为在低底物浓度下从头甲基化和维持甲基化的速率是相同的。
