DNA topoisomerases from rat liver: physiological variations.
DNA topoisomerases from rat liver: physiological variations.
复制标题
大鼠肝脏 DNA 拓扑异构酶：生理变化。
作者：
Michel Duguet;C. Lavenot;Francis Harper;Gilles Mirambeau;A. Recondo
除了切口闭合（拓扑异构酶I）活性，ATP依赖的DNA拓扑异构酶存在于大鼠肝细胞核中。该酶，部分纯化，是能够在体外的镁依赖性，ATP依赖性，组蛋白H1依赖性的反应，并decatenate在体外动质体DNA网络，以产生游离的微环中的镁依赖性和ATP依赖性的反应中的封闭的DNA环。它在很大程度上类似于其他真核II型拓扑异构酶的要求，并推测属于这类酶。I型和II型的活动进行了测量，在大鼠肝细胞核作为再生时间的函数部分肝切除术后：I型活动在此过程中没有显着变化。与此相反，II型活性大大增加，这表明可能参与的酶在DNA复制。
Besides the nicking-closing (topoisomerase I) activity, an ATP-dependent DNA topoisomerase is present in rat liver nuclei. The enzyme, partially purified, is able to catenate in vitro closed DNA circles in a magnesium-dependent, ATP-dependent, histone H1-dependent reaction, and to decatenate in vitro kinetoplast DNA networks to yield free minicircles in a magnesium-dependent and ATP-dependent reaction. It is largely similar to other eukaryotic type II topoisomerases in its requirements, and presumably belongs to this class of enzymes. Type I and type II activities were measured in rat liver nuclei as a function of regenerating time after partial hepatectomy: type I activity was not significantly changed during this process. In contrast, type II activity was considerably increased, suggesting a possible involvement of the enzyme in DNA replication.