Template Requirements of a DNA Polymerase from Ehrlich Ascites Tumor Cells

Abstract

A partially purified DNA polymerase from Ehrlich ascites tumor cells with a preference for native DNA has been analyzed with respect to different templates. Optimal activity was found at pH 7.25 with denatured, and pH 7.5 with native DNA template. Production of hyperchromicity by stepwise denaturation of native DNA and enzyme activity showed an inverse relationship. Maximal activity was achieved with partially degraded (activated) DNA as reported previously. Mixing of denatured and activated DNA templates at various proportions decreased priming ability to levels lower than with activated DNA used individually. The enzyme exhibited the same affinity for native and activated salmon sperm DNA (Km = 65 μg/ml). In contrast, substrate inhibition occurred with denatured DNA template with a K´s value of 730 μg/ml.