Eichler D C, Fisher P A, Korn D
J Biol Chem. 1977 Jun 10;252(11):4011-4.
It was recently reported (Lynch, W. E., Surrey, S., and Lieberman, I. (1975) J. Biol. Chem. 250, 8179-8183) that the extraction of regenerating rat liver in solutions of isotonic sucrose containing 4 mM CaCl2 leads to almost quantitative recovery of DNA polymerase alpha (Weissbach, A., Baltimore, D., Bollum, F., Gallo, R., and Korn, D. (1975) Science 190, 401--402) activity in the purified nuclear compartment. Our application of this method to the isolation of the DNA polymerase activities activities from cultured human epithelial and lymphoblastoid cells has led to substantially different results. We have observed that the inclusion of Ca2+ in either isotonic sucrose or hypotonic aqueous extraction media leads to the irreversible inactivation of the majority, cytoplasmic fraction of DNA polymerase alpha activity and is without quantitative effect on the recovery of the nuclear fraction of this activity.
最近有报道（林奇，W. E.，萨里，S.，利伯曼，I.（1975）《生物化学杂志》250，8179 - 8183）称，在含有4 mM氯化钙的等渗蔗糖溶液中提取再生大鼠肝脏，可使纯化的细胞核部分的DNA聚合酶α（魏斯巴赫，A.，巴尔的摩，D.，博勒姆，F.，加洛，R.，科恩，D.（1975）《科学》190，401 - 402）活性几乎实现定量回收。我们将此方法应用于从培养的人上皮细胞和淋巴母细胞样细胞中分离DNA聚合酶活性，得到了截然不同的结果。我们观察到，在等渗蔗糖或低渗水性提取介质中加入钙离子会导致大部分细胞质部分的DNA聚合酶α活性不可逆失活，且对该活性细胞核部分的回收没有定量影响。
