title: Purification and properties of RNA polymerase I from Ehrlich ascites cells.
abstract: DNA-dependent RNA polymerase I (or A) (nucleoside triphosphate:RNA nucleotidyltransferase, EC 2.7.7.6) was purified from Ehrlich ascites cells after solubilization from isolated nuclei. The purification was accomplished by a procedure involving initial precipitation with ammonium sulfate, following by chromatographies on DEAE-Sephadex and phosphocellulose ion exchange resins and gel filtration on Sepharose 6B. A chromatographically homogeneous enzyme was obtained which was purified about 2300-fold relative to nuclear extracts. The specific activity of the most purified enzyme fraction was 230 nmol of [3H]UTP incorporated into RNA per mg of protein in 10 min at 37 degrees C, which is similar to those reported for the highly purified RNA polymerase I from mouse myeloma and calf thymus. The elution position on Sepharose 6B gel filtration indicated a molecular weight of approx. 580 000. Analysis of the purified enzyme by polyacrylamide gel electrophoresis under nondenaturing conditions revealed only one protein band. Certain heterogeneity in the RNA polymerase I fractions was found in the early chromatographic steps, but not in the most purified fractions.
mesh_terms: D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000201:enzymology*; D012321:DNA-Directed RNA Polymerases / Q000302:isolation & purification; D008274:Magnesium / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D051379:Mice; D008970:Molecular Weight; D012318:RNA Polymerase I / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D008345:Manganese; D012321:DNA-Directed RNA Polymerases; D012318:RNA Polymerase I; D008274:Magnesium