Bhattacharya P, Basu S
Proc Natl Acad Sci U S A. 1978 Mar;75(3):1289-93. doi: 10.1073/pnas.75.3.1289.
The activities of two DNA polymerases (DNA nucleotidyltransferases) were characterized in mouse neuroblastoma clone N-18 on the basis of their apparent molecular weights (determined by sucrose density gradient centrifugation: polymerase-alpha, 7.5-8 S; polymerase-beta, 3-4 S) and relative inhibition by sulfhydryl-blocking agents. N-Ethylmaleimide (10 mM) and iodoacetamide (1.5 mM) inhibited DNA polymerase-alpha activity completely, whereas only 35-40% inhibition was observed for DNA polymerase-beta under similar conditions. DNA polymerase-alpha activity was reduced 50-70% in N-18 cells that had been induced to differentiate by 4 micro M bromodeoxyuridine, and the low molecular weight DNA polymerase-beta activity remain unchanged. With activated calf thymus DNA as template, only DNA polymerase-alpha activity was stimulated in the presence of added ribonucleotides and purified Escherichia coli RNA polymerase.
基于两种DNA聚合酶（DNA核苷酸转移酶）的表观分子量（通过蔗糖密度梯度离心法测定：聚合酶α，7.5 - 8S；聚合酶β，3 - 4S）以及巯基阻断剂对它们的相对抑制作用，对小鼠神经母细胞瘤克隆N - 18中的这两种酶的活性进行了表征。N - 乙基马来酰胺（10 mM）和碘乙酰胺（1.5 mM）可完全抑制DNA聚合酶α的活性，而在类似条件下，DNA聚合酶β仅出现35 - 40%的抑制。在经4 μM溴脱氧尿苷诱导分化的N - 18细胞中，DNA聚合酶α的活性降低了50 - 70%，而低分子量的DNA聚合酶β的活性保持不变。以活化的小牛胸腺DNA为模板，在添加核糖核苷酸和纯化的大肠杆菌RNA聚合酶的情况下，仅DNA聚合酶α的活性受到刺激。
