EUKARYOTIC DNA TOPOISOMERASES - 2 FORMS OF TYPE-I DNA TOPOISOMERASES FROM HELA-CELL NUCLEI
EUKARYOTIC DNA TOPOISOMERASES - 2 FORMS OF TYPE-I DNA TOPOISOMERASES FROM HELA-CELL NUCLEI
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DOI：
10.1073/pnas.78.6.3487
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发表时间：
1981-01-01
期刊：
影响因子：
--
通讯作者：
MILLER, KG
中科院分区：
文献类型：
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作者：
LIU, LF;MILLER, KG
从人宫颈癌细胞细胞核中纯化出两种I型DNA拓扑异构酶。一种拓扑异构酶的肽分子量为100,000，另一种为67,000。一些证据表明，这些拓扑异构酶是密切相关的。两者在DNA上表现出相似的酶活性。纯化过程中两种拓扑异构酶的色谱性质相似。纯化的mw100,000拓扑异构酶在体外轻度蛋白水解产生一组mw100,000 .apprxeq的蛋白条带。67,000，这些条带保持拓扑异构酶活性。在NaDodSO4[十二烷基硫酸钠]存在下，67,000拓扑异构酶的部分蛋白质水解形成的肽是100,000酶产生的肽的一个子集。100,000拓扑异构酶是细胞中主要的I型酶。67,000拓扑异构酶可能与先前鉴定的缺口闭合酶相同，可能是由100,000酶的蛋白质水解形成的。
Two type I DNA topoisomerases were purified to homogeneity from the nuclei of HeLa [human cervical carcinoma] cells. One topoisomerase has a peptide MW of 100,000 and the other, a MW of 67,000. Several lines of evidence indicate that these topoisomerases are closely related. Both exhibit similar enzymatic activities on DNA. The chromatographic properties of the 2 topoisomerases during purification are similar. Mild proteolysis of the purified MW 100,000 topoisomerase in vitro generates a group of protein bands of MW .apprxeq.67,000, and these bands retain topoisomerase activity. The peptides formed by partial proteolysis of the 67,000 topoisomerase in the presence of NaDodSO4 [sodium dodecyl sulfate] form a subset of those produced from the 100,000 enzyme. The 100,000 topoisomerase is the major type I enzyme in the cell. The 67,000 topoisomerase, which may be identical to the previously identified nicking-closing enzyme is probably formed by proteolysis of the 100,000 enzyme.