Craig R K, Keir H M
Biochem J. 1975 Feb;145(2):225-32. doi: 10.1042/bj1450225.
Nuclear and cytoplasmic fractions were prepared from exponentially-growing BHK-21/C13 cells; DNA polymerase was extracted from them and analysed by gel filtration and sucrose-density-gradient centrifugation. DNA polymerase I is heterogeneous comprising species covering a considerable range of molecular weights. These have been tentatively identified as four subspecies of apparent molecular weights 900000-1000000 (IA), 460000-560000 (IB), 270000-320000 (IC) and 140000-200000 (ID), as assessed by gel filtration through Sepharose 6B. DNA polymerase II has a mol.wt. of 46000 +/- 4000 as assessed by gel filtration on Sepharose 6B, and 48000 +/- 2000 as assessed by gel filtration on Sephadex G-100. Sedimentation analyses on sucrose density gradients showed that the DNA polymerase I species had sedimentation coefficients predominantly in the range 6-8 S. DNA polymerase II had predominantly a sedimentation coefficient of 3.2 S although a component with lower sedimentation coefficient was found. The lack of correlation between the molecular weights derived from gel filtration and the sedimentation coefficients is attributed to molecular asymmetry. DNA polymerase I was found to be associated predominantly with the cytoplasm although certain types of nuclear preparation contained large amounts of it. DNA polymerase II was found to be mostly if not exclusively in nuclear preparations.
从指数生长的BHK - 21/C13细胞中制备细胞核和细胞质组分；从中提取DNA聚合酶，并通过凝胶过滤和蔗糖密度梯度离心进行分析。DNA聚合酶I是异质的，由覆盖相当大范围分子量的种类组成。通过Sepharose 6B凝胶过滤评估，这些种类暂被鉴定为表观分子量900000 - 1000000（IA）、460000 - 560000（IB）、270000 - 320000（IC）和140000 - 200000（ID）的四个亚类。通过Sepharose 6B凝胶过滤评估，DNA聚合酶II的分子量为46000±4000，通过Sephadex G - 100凝胶过滤评估为48000±2000。蔗糖密度梯度沉降分析表明，DNA聚合酶I种类的沉降系数主要在6 - 8 S范围内。DNA聚合酶II的沉降系数主要为3.2 S，尽管发现了一个沉降系数较低的组分。凝胶过滤得出的分子量与沉降系数之间缺乏相关性归因于分子不对称性。发现DNA聚合酶I主要与细胞质相关，尽管某些类型的细胞核制备物中含有大量该酶。发现DNA聚合酶II大多（如果不是全部）存在于细胞核制备物中。
