来自海拉细胞核的DNA甲基化酶。
DNA methylase from HeLa cell nuclei.
作者信息
Roy P H, Weissbach A
出版信息
Nucleic Acids Res. 1975 Oct;2(10):1669-84. doi: 10.1093/nar/2.10.1669.
A DNA methylase has been purified 270-fold from HeLa cell nuclei by chromatography on DEAE-cellulose, phosphocellulose, and hydroxyapatite. The enzyme transfers methyl groups from S-adenosyl-L-methionine to cytosine residues in DNA. The sole product of the reaction has been identified as 5-methylcytosine. The enzyme is able to methylate homologous (HeLa) DNA, although to a lesser extent than heterologous DNA. This may be due to incomplete methylation of HeLa DNA synthesized in vivo. The HeLa enzyme can methylate single-stranded DNA, and does so to an extent three times greater than that of the corresponding double-stranded DNA. In single-stranded M. luteus DNA, at least 2.4% of the cytosine residues can be methylated in vitro by the enzyme. The enzyme also can methylate poly (dG-dC-dG-dC) and poly (dG, dC). Bilateral nearest neighbors to the 5-methylcytosine have been determined with M. luteus DNA in vitro and HeLa DNA in vivo. The 5' neighbor can be either G or C while the 3' neighbor is always G and this sequence is, thus, p(G/C)pmCpG.
通过在二乙氨基乙基纤维素、磷酸纤维素和羟基磷灰石上进行层析，已从海拉细胞核中纯化出一种DNA甲基化酶，其纯化倍数达270倍。该酶将甲基从S-腺苷-L-甲硫氨酸转移至DNA中的胞嘧啶残基上。反应的唯一产物已被鉴定为5-甲基胞嘧啶。该酶能够使同源（海拉）DNA甲基化，尽管程度低于异源DNA。这可能是由于体内合成的海拉DNA甲基化不完全所致。海拉酶能够使单链DNA甲基化，其程度比相应双链DNA高三倍。在单链藤黄微球菌DNA中，该酶在体外至少可使2.4%的胞嘧啶残基甲基化。该酶还能使聚（dG-dC-dG-dC）和聚（dG，dC）甲基化。已在体外对藤黄微球菌DNA以及在体内对海拉DNA确定了5-甲基胞嘧啶的两侧最近邻碱基。5'邻碱基可以是G或C，而3'邻碱基总是G，因此该序列为p（G/C）pmCpG。
Zotero 插件