小牛胸腺DNA聚合酶α催化从头合成脱氧腺苷酸和脱氧胸苷酸聚合物。
De novo synthesis of a polymer of deoxyadenylate and deoxythymidylate by calf thymus DNA polymerase alpha.
作者信息
Henner D, Furth J J
出版信息
Proc Natl Acad Sci U S A. 1975 Oct;72(10):3944-6. doi: 10.1073/pnas.72.10.3944.
In a reaction mixture containing calf thymus DNA polymerase alpha (DNA nucleotidyltransferase; deoxynucleosidetriphosphate:DNA deoxynucleotidyltransferase; EC 2.7.7.7), calf thymus DNA unwinding protein, DNA, deoxyadenosine 5'-triphosphate and deoxythymidine 5'-triphosphate, a copolymer of deoxyadenylate and deoxythymidylate is synthesized after a lag period of 1-2 hr. In the presence of the four deoxyribonucleoside triphosphates only deoxyadenylate and deoxythymidylate are incorporated into the polymer and the rate of synthesis is decreased. The reaction variably occurs in the absence of DNA or DNA unwinding protein but with a greatly entended lag period. The optimal Mg2+ concentration for synthesis of the polymer of deoxyadenylate and deoxythymidylate is 1 mM, in contrast to an optimal Mg2+ concentration of 8 mM for DNA synthesis with activated DNA as template. Characterization of the product of de novo synthesis indicates that it is the alternating copolymer, poly(dA-dT).
在含有小牛胸腺DNA聚合酶α（DNA核苷酸转移酶；脱氧核苷三磷酸：DNA脱氧核苷酸转移酶；EC 2.7.7.7）、小牛胸腺DNA解旋蛋白、DNA、脱氧腺苷5'-三磷酸和脱氧胸苷5'-三磷酸的反应混合物中，经过1-2小时的延迟期后，合成了脱氧腺苷酸和脱氧胸苷酸的共聚物。在四种脱氧核糖核苷三磷酸存在的情况下，只有脱氧腺苷酸和脱氧胸苷酸被掺入聚合物中，并且合成速率降低。该反应在没有DNA或DNA解旋蛋白的情况下可变地发生，但延迟期大大延长。与以活化DNA为模板进行DNA合成时8 mM的最佳Mg2+浓度相比，合成脱氧腺苷酸和脱氧胸苷酸聚合物的最佳Mg2+浓度为1 mM。从头合成产物的表征表明它是交替共聚物聚（dA-dT）。
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