Experimental conditions affecting ribonucleic acid polymerase in isolated rat liver nuclei. Effect of nucleoside triphosphate concentration, temperature, ammonium sulphate and heparin

作者：Francesco Novello, Fiorenzo Stirpe · 发表于：Biochemical Journal · 年份：1969 · DOI：10.1042/bj1120721 · 被引用次数：53 · 研究领域：Drug Transport and Resistance Mechanisms、Enzyme Structure and Function、HIV/AIDS drug development and treatment

1. The conditions affecting the activity of RNA polymerase in isolated rat liver nuclei were studied with Mg(2+) or Mn(2+) as activating ions. 2. The enzyme assayed with Mg(2+) and at low ionic strength is saturated by a lower concentration of nucleotide substrates than if assayed with Mn(2+) at low ionic strength or with either ion at high ionic strength. 3. At low and at high ionic strength the incorporation of AMP is affected in a similar way by variations in the temperature of incubation. Preincubation at 37 degrees impairs the AMP incorporation. 4. Heparin stimulates the RNA polymerase activity in the presence of Mn(2+). 5. Both ammonium sulphate and heparin ;restart' the reaction if added after 15min., the effect being more marked with ammonium sulphate than with heparin, and also more marked in the presence of Mn(2+) than of Mg(2+). 6. alpha-Amanitin abolishes the effect of ammonium sulphate and of heparin.