Reale A, Lindsay H, Saluz H P, Pradhan S, Adams R L, Jost J P, Strom R
Institute of Biomedical and Life Sciences, University of Glasgow, Scotland, U.K.
Biochem J. 1995 Dec 15;312 ( Pt 3)(Pt 3):855-61. doi: 10.1042/bj3120855.
By using a purified fraction of mouse DNA methyltransferase we have shown, by gel-retardation analysis, that the enzyme forms a low-affinity complex preferentially with hemimethylated DNA; the complexes formed with unmethylated or with fully methylated DNA are of even lower affinity, and only very weak interaction occurs with DNA lacking CG dinucleotides. Interaction is inhibited by N-ethylmaleimide. Methyl transfer from S-adenosyl-methionine is associated with the release of the fully methylated product from the complex. Complexes formed with the intact enzyme are extremely large, but limited trypsin treatment allows a major complex to enter the gel. DNA binding is not inhibited by this limited proteolysis of the native enzyme.
通过使用纯化的小鼠DNA甲基转移酶组分，我们通过凝胶阻滞分析表明，该酶优先与半甲基化DNA形成低亲和力复合物；与未甲基化或完全甲基化DNA形成的复合物亲和力更低，并且与缺乏CG二核苷酸的DNA仅发生非常微弱的相互作用。相互作用受到N-乙基马来酰亚胺的抑制。从S-腺苷甲硫氨酸的甲基转移与复合物中完全甲基化产物的释放相关。与完整酶形成的复合物非常大，但有限的胰蛋白酶处理可使主要复合物进入凝胶。天然酶的这种有限蛋白水解不会抑制DNA结合。
