Novak B, Baril E F
Nucleic Acids Res. 1978 Jan;5(1):221-39. doi: 10.1093/nar/5.1.221.
A non-enzymic protein factor that increases the in vitro rate of synthesis by HeLa DNA polymerase alpha 15- to 30-fold with denatured DNA as template has been partially purified from the cytoplasmic fraction of HeLa cells. The stimulatory effect is highly specific for HeLa DNA polymerase alpha and for DNA templates that contain extensive regions of single-strandedness. Synthesis with denatured DNA as template presumably proceeds from 3'-hydroxyl termini formed at loop-back regions since the synthesized DNA product and template are covalently linked. The stimulatory protein factor chromatographs as a basic protein, has an approximate molecular weight of 30,000 daltons and binds with moderate affinity to denatured DNA cellulose, being eluted by o.4M NaCl. The purified factor lacks detectable DNA polymerase, exo- and endodeoxyribonuclease and RNA polymerase activities. It also does not promote helix-coil transitions with poly[d(A-T)] and Clostridium perfringens DNA.
一种非酶蛋白因子已从HeLa细胞的细胞质部分中得到部分纯化，该因子能以变性DNA为模板，使HeLa DNA聚合酶α的体外合成速率提高15至30倍。这种刺激作用对HeLa DNA聚合酶α以及含有大量单链区域的DNA模板具有高度特异性。以变性DNA为模板的合成大概是从环回区域形成的3'-羟基末端开始的，因为合成的DNA产物与模板是共价连接的。这种刺激蛋白因子在色谱分析中表现为一种碱性蛋白，分子量约为30,000道尔顿，与变性DNA纤维素具有中等亲和力，能被0.4M NaCl洗脱。纯化后的因子缺乏可检测到的DNA聚合酶、外切和内切脱氧核糖核酸酶以及RNA聚合酶活性。它也不能促进聚[d(A-T)]和产气荚膜梭菌DNA的螺旋-卷曲转变。
