[Effect of bleomycin on DNA-dependent RNA polymerase purified from normal and neoplastic tissues]. / Effetto della bleomicina sulie RNA polimerasi DNA-dipendenti purificate da tessuti normali e neoplastici.

The effect of bleomycin was investigated using two forms of DNA-dependent RNA polymerase (A and B) purified from normal tissues and experimental tumours in presence either of Mn2+ or Mg2+ and native or denatured homologous DNA. THe results show that the antibiotic inhibits the enzyme activity of both classes, and the degree of inhibition appears to be influenced by the nature of cation, the highest values being reached with Mg2+. Moreover, the denaturation of DNA modify the bleomycin effect significantly. With regard to cellular damage induced by the drug, the data here reported show that there is not a substantial difference between normal and tumour tissues.

[Effect of actinomycin D on purified DNA-dependent RNA polymerases from normal and neoplastic tissues]. / Effetto dell'actinomicina D sulle RNA polimerasi DNA-dipendenti purificate da tessuti normali e neoplastici.

The effect of low concentrations of actinomycin D was investigated, using two forms of DNA-dependent RNA polymerase (A and B) purified from normal tissues and experimental tumours, in the presence either of Mn2+ or Mg2+, and homologous DNA. The A enzyme activity was strongly inhibited by the antibiotic in presence of Mg2+ and much less in presence of Mn2+. The B enzyme activity was almost suppressed in presence of both cations. The results here reported provide support that the actinomycin D induce a cellular damage of the same extent in normal and tumour tissues.