Enzymic synthesis of RNA from T7 DNA

Abstract

RNA polymerase catalyzes the synthesis of RNA chains at a rate of seven nucleotides per second per growing RNA molecule at 37 °C. The RNA chains grow in a complex with the DNA that is not dissociable by 0.5 m-KCl but can be dissociated by 0.2% sodium dodecyl sulfate. By twenty minutes, RNA with a number average molecular weight of 1 × 10 6 is synthesized. Longer incubation times yield many molecules with molecular weights in the 2 to 3 × 10 6 range. Up to fifty RNA molecules can be made per DNA molecule in ten minutes without affecting the growth rate of individual chains. Proflavine at 12 μg/ml. was found not to limit the growth rate of the RNA chains, whereas actinomycin D at 0.4 mμmole/ml. does.