Briat J F, Mache R
Eur J Biochem. 1980 Oct;111(2):503-9. doi: 10.1111/j.1432-1033.1980.tb04966.x.
A chloroplast RNA polymerase has been isolated from a transcriptionally active spinach plastid DNA-protein complex. The properties of the complex and of the reconstituted system have been compared. The crude enzyme is at least sevenfold less active when compared with the complex. RNA synthesis by the reconstituted system is sensitive to high ionic strength and heparin, contrarily to RNA synthesis by the chloroplast DNA-protein complex. On the other hand, rifampicin has no inhibitory effect whatever on the transcriptional system used. The RNA polymerase isolated is more efficient with denatured DNA than with double-stranded DNA and the best template is chloroplast DNA. The crude RNA polymerase isolated migrates in a peak of 11 S in glycerol gradient centrifugation and is located in a single band in non-denaturing polyacrylamide gel electrophoresis. About 30 polypeptides (Mr 15 000--180 000) are part of the complex and only eight of them are found in the RNA polymerase preparation. Only five polypeptides are always present with the same yield. They are probably the subunits of the RNA polymerase. The molecular weight of these subunits ranged from 15 000--69 000, even if the isolation of the enzyme was performed in the presence of protease inhibitors.
已从转录活性的菠菜质体DNA-蛋白质复合物中分离出一种叶绿体RNA聚合酶。对该复合物和重组系统的特性进行了比较。与复合物相比，粗酶的活性至少低七倍。与叶绿体DNA-蛋白质复合物的RNA合成相反，重组系统的RNA合成对高离子强度和肝素敏感。另一方面，利福平对所使用的转录系统没有任何抑制作用。分离出的RNA聚合酶对变性DNA的效率比对双链DNA的效率更高，最佳模板是叶绿体DNA。分离出的粗RNA聚合酶在甘油梯度离心中以11S的峰迁移，并且在非变性聚丙烯酰胺凝胶电泳中位于单一带中。约30种多肽（分子量15000-180000）是该复合物的一部分，其中只有8种存在于RNA聚合酶制剂中。只有5种多肽总是以相同的产量存在。它们可能是RNA聚合酶的亚基。即使在蛋白酶抑制剂存在的情况下进行酶的分离，这些亚基的分子量仍在15000-69000之间。
