Two types of adriamycin inhibition of a homologous RNA synthesizing system from L1210 cells.

Purified L1210 RNA polymerase II was utilized to study the effect of adriamycin on the kinetics of RNA synthesis. In this study it was found that the adriamycin induced two types of inhibition of RNA synthesis with native DNA as a template. At low drug/DNA-P molar ratios, adriamycin functions as an uncompetitive inhibitor, whereas at high drug/DNA-P molar ratios adriamycin inhibits RNA synthesis competitively. However, when denatured DNA was utilized as template, only competitive inhibition was observed. It is proposed that two modes of inhibition of native DNA-dependent RNA synthesis represents two types of adriamycin-DNA complexes.