Yoshida S, Cavalieri L F
Proc Natl Acad Sci U S A. 1971 Jan;68(1):200-4. doi: 10.1073/pnas.68.1.200.
DNA polymerase activity from Escherichia coli can be demonstrated in various sized molecules ranging in molecular weight from about 10,000 to 120,000 or higher. The characterization of the smaller species is difficult because of their pronounced tendency toward aggregation; the smallest apparently aggregates most readily. The results indicate the following molecular weight classes: 10,000-20,000; 40,000-50,000; 75,000-85,000, and 100,000-120,000. The same classes were obtained with several methods of analysis of material that had been purified in a number of ways, one of which is a new DNA-acrylamide gel chromatographic procedure. The lowest molecular weight species shows no exonucleolytic activity. A proteolytic inhibitor, phenylmethyl sulfonylfluoride, did not eliminate the small active molecules, although proteolysis of high molecular weight DNA polymerase (109,000) has been shown by others to produce fragments of about 75,000 molecular weight. Either there is a naturally occurring polymerase protein of about 20,000 molecular weight, capable of aggregation with itself and with certain other molecules (e.g., exonucleases), or there are certain bonds in a large, native polymerase molecule that are especially susceptible to proteolysis without destroying activity.
大肠杆菌的DNA聚合酶活性可在分子量约为10,000至120,000或更高的各种大小的分子中得到证实。较小分子的特性难以确定，因为它们有明显的聚集倾向；最小的分子显然最容易聚集。结果表明存在以下分子量类别：10,000 - 20,000；40,000 - 50,000；75,000 - 85,000和100,000 - 120,000。通过几种分析方法对以多种方式纯化的材料进行分析，得到了相同的类别，其中一种方法是新的DNA - 丙烯酰胺凝胶色谱法。分子量最低的分子没有核酸外切酶活性。一种蛋白水解抑制剂，苯甲基磺酰氟，并没有消除小的活性分子，尽管其他人已表明高分子量DNA聚合酶（109,000）的蛋白水解会产生分子量约为75,000的片段。要么存在一种天然存在的分子量约为20,000的聚合酶蛋白，它能够自身聚集并与某些其他分子（例如核酸外切酶）聚集，要么在一个大的天然聚合酶分子中存在某些特别容易被蛋白水解而不破坏活性的键。
