SOLUBLE RNA POLYMERASE FROM RAT LIVER NUCLEI

RNA polymerase (nucleosidetriphosphate:RNA nucleotidyltransferase, EC 2.7.7.6) was extracted from rat liver nuclei in a soluble form. When the preparation was carried out on a sufficiently large scale to minimize adsorption losses, up to 80% of the activity and about 10% of the DNA of the intact nuclei were extracted. Elution of this soluble RNA polymerase from columns of DEAE-cellulose with ammonium sulfate yielded a single peak of activity which amounted to approx. 50% of the initial activity and which contained no more than 7% of the DNA of the soluble extract. The activity in this peak was completely dependent on added DNA and required the presence of Mn2+. Its pH optimum was close to 8.5. Centrifugation of the RNA polymerase in a sucrose gradient yielded a single peak of activity having a sedimentation coefficient of approx. 16 S. The ratios of incorporation of the four labeled nucleoside triphosphates catalyzed by this enzyme resembled those of the labeled nucleoside triphosphates catalyzed by this enzyme resembled those of the calf thymus DNA used as a primer and were essentially identical to those obtained with purified Escherichia coli RNA polymerase under similar conditions. © 1969.