Inhibition of transfer ribonucleic acid nucleotidyl transferase (EC 2.7.7.25) from Ehrlich tumor cells by proflavine sulfate and ethidium bromide.

Transfer RNA nucleotidyl transferase from Ehrlich tumor cells was inhibited by proflavine sulfate and ethidium bromide but not by actinomycin D, chromomycin, rifamycin SV, rifampin, daunomycin, or alpha-amanitin. Complete inhibition of nucleotidyl transferase activity was attained at a final concentration of 1 mmol/1 proflavine sulfate, while 2 mmol/1 ethidium bromide was required to completely inhibit the enzyme. CMP incorporation into tRNA was more sensitive to both proflavine sulfate and ethidium bromide than was AMP incorporation.