梨形四膜虫中两种DNA聚合酶的存在。
Presence of two DNA polymerases in Tetrahymena pyriformis.
作者信息
Furukawa Y, Yamada R H, Kohno M
出版信息
Nucleic Acids Res. 1979 Dec 20;7(8):2387-98. doi: 10.1093/nar/7.8.2387.
Two DNA polymerases were detected in Tetrahymena pyriformis, strain GL. One (enzyme I) was sensitive to N-ethylmaleimide, while the other (enzyme II) was insensitive. The molecular weight of the enzymes, as determined by glycerol gradient centrifugation analysis, were approximately 130,000 and 70,000, respectively. Optimal concentration of MgCl2 was 10mM for enzyme I and 18mM for enzyme II. KCl inhibited enzyme I but stimulated enzyme II. Poly (dA-dT) served effectively as a template for enzyme I, while poly(dA).(dT)12-18 was an effective template for enzyme II. Enzyme I activity increased with cell growth and sharply declined after the cells reached the stationary phase. On the other hand, enzyme II activity appeared only at the end of log phase. In cells synchronized by starvation-refeeding technique enzyme I was markedly stimulated in correspondence to the rate of DNA synthesis, whereas the level of enzyme II activity changed to lesser extent. By ethidium bromide treatment, only enzyme I activity was induced.
在梨形四膜虫GL株中检测到两种DNA聚合酶。一种（酶I）对N-乙基马来酰亚胺敏感，而另一种（酶II）不敏感。通过甘油梯度离心分析测定，这两种酶的分子量分别约为130,000和70,000。酶I的MgCl2最佳浓度为10mM，酶II为18mM。KCl抑制酶I但刺激酶II。聚（dA-dT）有效地作为酶I的模板，而聚（dA）·（dT）12-18是酶II的有效模板。酶I的活性随细胞生长而增加，在细胞达到稳定期后急剧下降。另一方面，酶II的活性仅在对数期结束时出现。在通过饥饿-再投喂技术同步化的细胞中，酶I与DNA合成速率相对应地受到明显刺激，而酶II活性水平变化较小。通过溴化乙锭处理，仅诱导了酶I的活性。
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