Liberator P A, Bresnick E
Chem Biol Interact. 1981 Dec;38(1):53-73. doi: 10.1016/0009-2797(81)90153-8.
The administration of 3-methylcholanthrene (MC) to rats results in a marked increase in the specific activities of hepatic RNA polymerases I and II. In the present study, we were able to show that this increase was not caused by a shift in the ratio of 'free' to 'template-engaged' RNA polymerase. By means of binding studies with [3H]amatoxin, we were unable to demonstrate any increase in the number of RNA polymerase II molecules in liver after MC administration to the rats. RNA polymerase I was purified in excess of 3000-fold from hepatic nuclei isolated both from control and MC-treated rats. The stimulation in activity was demonstrated at each step in the purification scheme until glycerol sedimentation analysis. Results from cation-exchange chromatography on phosphocellulose indicated that the polycyclic hydrocarbon increased the enzyme activity of RNA polymerase Ib somewhat specifically. Subsequent to glycerol gradient centrifugation, this stimulatory advantage was no longer evident. Reconstitution experiments revealed the presence of a stimulatory component, which was demonstrated in low molecular weight fractions from both control and experimental preparations.
给大鼠施用3-甲基胆蒽（MC）会导致肝RNA聚合酶I和II的比活性显著增加。在本研究中，我们能够表明这种增加不是由“游离”与“模板结合”RNA聚合酶的比例变化引起的。通过用[3H]鹅膏毒素进行结合研究，我们未能证明给大鼠施用MC后肝脏中RNA聚合酶II分子数量有任何增加。从对照大鼠和MC处理大鼠分离的肝细胞核中，RNA聚合酶I被纯化了超过3000倍。在纯化方案的每个步骤直至甘油沉降分析，都证明了活性的刺激作用。磷酸纤维素阳离子交换色谱结果表明，多环烃在一定程度上特异性地增加了RNA聚合酶Ib的酶活性。甘油梯度离心后，这种刺激优势不再明显。重组实验揭示了一种刺激成分的存在，在对照和实验制剂的低分子量级分中都得到了证实。
