Nowak R, Kulik J, Siedlecki J A
Department of Cell Biology and Experimental Therapy, Cancer Center of the Maria Sklodowska-Curie Institute, Warszawa, Poland.
Acta Biochim Pol. 1987;34(2):205-15.
Study was made of the ability of calf thymus DNA polymerases alpha and beta to replicate templates containing a small gap. It was found that during extensive replication of activated DNA or synthetic template.primers or specially prepared circular DNA containing a small gap, catalyzed by DNA polymerase alpha, the levels of incorporated nucleotides corresponded to the amounts of the single-stranded fraction of these templates. In contrast, in the reaction catalyzed by DNA polymerase beta the amounts of products were several times greater. The ability to synthesize the product in a great excess was a specific feature of the latter enzyme. An analysis of the gap-filling products by sucrose gradient centrifugation, gel electrophoresis and Southern hybridization showed that, contrary to DNA polymerase alpha, DNA polymerase beta exhibited the ability to synthesize DNA not only within but also beyond the gap. The "net" DNA product is complementary to the template strand. It is suggested that DNA was synthesized beyond the gap by displacement of the non-replicated strand.
对小牛胸腺DNA聚合酶α和β复制含有小缺口模板的能力进行了研究。结果发现，在DNA聚合酶α催化下，对活化DNA或合成模板引物或特别制备的含有小缺口的环状DNA进行大量复制时，掺入核苷酸的水平与这些模板单链部分的量相对应。相反，在DNA聚合酶β催化的反应中，产物的量要大几倍。大量合成产物的能力是后一种酶的一个特殊特征。通过蔗糖梯度离心、凝胶电泳和Southern杂交对缺口填充产物进行分析表明，与DNA聚合酶α不同，DNA聚合酶β不仅能够在缺口内而且能够在缺口外合成DNA。“净”DNA产物与模板链互补。有人提出，DNA是通过未复制链的置换在缺口外合成的。
