A comparative study of nuclear and chloroplast DNA dependent RNA polymerases from wheat leaves

• 1.1. Three DNA dependent RNA polymerases have been purified from chromatin and chloroplast fractions of wheat leaves.
• 2.2. The purified enzymes were completely dependent on exogenous DNA after purification by glycerol gradient, DEAE-Sephadex and phosphocellulose chromatography.
• 3.3. The nuclear enzymes, I and II, showed a strong preference for denatured nuclear DNA, whereas the chloroplast enzyme preferred denatured chloroplast DNA.
• 4.4. The three enzymes require either Mg²⁺ or Mn²⁺ for activity.
• 5.5. α-amanitin specifically inhibited RNA polymerase II but has no effect on polymerase I and chloroplast polymerase.
• 6.6. Enzyme I is most active at very low ionic strength (0.10 mM KC1), whereas enzyme II and chloroplast enzyme show maximum activity at 150mM and 50 mM KC1 respectively.