Purification of a 9S DNA polymerase alpha species from calf thymus.

a DNA polymerase alpha species from calf thymus has been purified 12 000-fold to near homogeneity. The enzyme sediments under high salt conditions in the preparative ultracentrifuge as a homogeneous band at 9S. The specific activity is 50 000-70 000 units/mg of protein. Polypeptides of 148 000, 59 000, and 48 000 daltons are detectable. The molecular weight as estimated from gradient gel electrophoresis is about 500 000. The 9S DNA polymerase is free from terminal nucleotidyl transferase activity and does not exhibit endonuclease or exonuclease activity. It is inhibited by low concentrations of salt, aphidicolin, and N-ethylmaleimide.