Bolden A H, Nalin C M, Ward C A, Poonian M S, Weissbach A
Mol Cell Biol. 1986 Apr;6(4):1135-40. doi: 10.1128/mcb.6.4.1135-1140.1986.
Analysis of the enzymatic methylation of oligodeoxynucleotides containing multiple C-G groups showed that hemimethylated sites in duplex oligomers are not significantly methylated by human or murine DNA methyltransferase unless those sites are capable of being methylated de novo in the single- or double-stranded oligomers. Thus, the primary sequence of the target strand, rather than the methylation pattern of the complementary strand, determines maintenance methylation. This suggests that de novo and maintenance methylation are the same process catalyzed by the same enzyme. In addition, the study revealed that complementary strands of oligodeoxynucleotides are methylated at different rates and in different patterns. Both primary DNA sequence and the spacing between C-G groups seem important since in one case studied, maximal methylation required a specific spacing of 13 to 17 nucleotides between C-G pairs.
对含有多个C-G基团的寡脱氧核苷酸的酶促甲基化分析表明，双链寡聚物中的半甲基化位点不会被人或鼠DNA甲基转移酶显著甲基化，除非这些位点能够在单链或双链寡聚物中从头甲基化。因此，靶链的一级序列而非互补链的甲基化模式决定了维持甲基化。这表明从头甲基化和维持甲基化是由同一酶催化的相同过程。此外，该研究还揭示，寡脱氧核苷酸的互补链以不同的速率和模式进行甲基化。一级DNA序列和C-G基团之间的间距似乎都很重要，因为在所研究的一个案例中，最大甲基化需要C-G对之间有13至17个核苷酸的特定间距。
