Kieber J J, Lopez M F, Tissier A F, Signer E
Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
Plant Mol Biol. 1992 Mar;18(5):865-71. doi: 10.1007/BF00019201.
We have purified a topoisomerase activity from broccoli (Brassica oleracea var. italica) to near homogeneity. The enzyme is an 80 kDa monomer as judged by gel filtration chromatography and SDS gel electrophoresis, though it may represent a proteolytic fragment of a larger protein. The enzyme is capable of removing both negative and positive supercoils in steps of one, does not absolutely require Mg2+, is only very weakly stimulated by NaCl, is inhibited by camptothecin, and cross-reacts with an antibody directed against human DNA topoisomerase I. These properties identify the enzyme as a eukaryotic type I topoisomerase.
我们已从西兰花（Brassica oleracea var. italica）中纯化出一种拓扑异构酶活性，纯度近乎均一。通过凝胶过滤色谱法和SDS凝胶电泳判断，该酶是一种80 kDa的单体，不过它可能是一种更大蛋白质的蛋白水解片段。该酶能够以单步方式去除负超螺旋和正超螺旋，并非绝对需要Mg2+，仅受NaCl非常微弱的刺激，受喜树碱抑制，并且能与针对人类DNA拓扑异构酶I的抗体发生交叉反应。这些特性表明该酶为真核生物I型拓扑异构酶。
