Mechanism of action of bleomycin. Studies with the growing culture of bacterial and tumor cells.

Bleomycin was observed to inhibit DNA and protein syntheses in intact Escherichia coli, Ehrlich carcinoma and HeLa cells. DNA synthesis was more profoundly affected than protein synthesis. RNA synthesis was not significantly suppressed by the antibiotic. The activity of bleomycin was highly dependent on the number of cells and on the concentration of phosphate in the medium, being more pronounced at low concentration of phosphate and with fewer cells. Bleomycin complex, copper-free bleomycin A2, copper-chelating bleomycin A2 (Cu 2.6 % w/w) and copper-saturated bleomycin A2 (Cu 5.1 %) were