Castroviejo M, Graves P V, Tharaud D, Hevia-Campos E, Litvak S
Biochimie. 1982 Mar;64(3):195-202. doi: 10.1016/s0300-9084(82)80469-0.
Plant DNA polymerases and E. coli DNA polymerase I, but not animal DNA polymerases or avian reverse transcriptase, are strongly stimulated by ethidium bromide (EtdBr) when TMP incorporation is followed using a short oligo dT primer at 37 degrees C. The effect is observed with a poly A template in the presence of Mg2+ or Mn2+ and of poly dA template only in the presence of magnesium ions. When a longer primer like poly dT is used, EdtBr inhibited wheat DNA polymerase C activity. This result prompted us to study the effect of the incubation temperature on the drug mediated stimulation. With oligo dT primer the stimulation by EdtBr is not observed at a temperature of incubation lower than 35 degrees C. It is shown that the Tm of poly A-dT12 is around 35 degrees C and that EdtBr will clearly increase this value. The stimulation is lost when the enzyme is preincubated with the primer alone whereas it is not affected when the enzyme is preincubated with the template.
当在37℃使用短寡聚dT引物跟踪胸苷酸（TMP）掺入时，溴化乙锭（EtdBr）能强烈刺激植物DNA聚合酶和大肠杆菌DNA聚合酶I，但不刺激动物DNA聚合酶或禽逆转录酶。在Mg2+或Mn2+存在下，使用聚A模板可观察到这种效应，而仅在镁离子存在下，使用聚dA模板时才会观察到这种效应。当使用较长的引物如聚dT时，EtdBr会抑制小麦DNA聚合酶C的活性。这一结果促使我们研究孵育温度对药物介导的刺激作用的影响。使用寡聚dT引物时，在低于35℃的孵育温度下未观察到EtdBr的刺激作用。结果表明，聚A-dT12的解链温度（Tm）约为35℃，并且EtdBr会明显提高该值。当酶单独与引物预孵育时，刺激作用消失，而当酶与模板预孵育时，刺激作用不受影响。
