Sensitivity of the DNA polymerase activities of Tetrahymena pyriformis to cytosine arabinoside triphosphate and N-ethyl-maleiimide.

Two DNA polymerase activities from Tetrahymena pyriformis were studied. The cytoplasmic polymerase was inhibited by cytosine arabinoside triphosphate (ara-CTP) and N-ethylmaleiimide (NEM) whereas the nuclear enzyme was not inhibited by araCTP and was inhibited by NEM to a lesser extent. The two enzymes could use CsCl, NaCl, and LiCl instead of KCl to varying degrees in the polymerase reaction. The two activities showed optimum activity at different concentrations of NaCl and KCl.