[Heliomycin suppression of RNA synthesis in a cell-free system].

Heliomycin inhibited in vitro the RNA-polymerase reaction catalyzed by the preparation of DNA-dependent RNA-polymerase from E. coli. The blocking effect increased with a rise in the antibiotic concentration. The inhibitory effect of heliomycin decreased, when the amount of RNA-polymerase in the system increased. Yet, it did not depend on the content of DNA and the nature of the DNA preparation. Preincubation of RNA-polymerase with DNA resulting in formation of the enzyme-matrix complex did not prevent blocking RNA synthesis by heliomycin. Suppression of the RNA-polymerase reaction did not depend on the time of the antibiotic addition to the polymerizing system. Heliomycin had a significant activity not only with respect to the bacterial RNA-polymerase, but also in the system containing the enzyme isolated from the cells of Crithidia oncopelti.