Rowe T C, Rusche J R, Brougham M J, Holloman W K
J Biol Chem. 1981 Oct 25;256(20):10354-61.
The lower eukaryote Ustilago maydis contains a topoisomerase that removes supercoils from negative and positive superhelical DNA. The enzyme may be a multimeric protein or an aggregate of polypeptides with a native molecular weight of 270,000 as estimated by gel filtration. No cofactors are required by the enzyme, but activity is enhanced by Mg2+. Dependence of activity upon enzyme concentration is not linear. Below a threshold level where topoisomerase cannot ordinarily be detected, addition of H1 histone sharply stimulates activity. ATP and a number of structural analogues inhibit the enzyme.
低等真核生物玉米黑粉菌含有一种拓扑异构酶，该酶可去除负超螺旋和正超螺旋DNA中的超螺旋。通过凝胶过滤估计，该酶可能是一种多聚体蛋白或多肽聚集体，其天然分子量为270,000。该酶不需要辅因子，但Mg2+可增强其活性。酶活性对酶浓度的依赖性并非呈线性。在通常无法检测到拓扑异构酶的阈值水平以下，添加H1组蛋白会显著刺激活性。ATP和许多结构类似物会抑制该酶。
