Inhibitory effect of duramycin on partial reactions catalyzed by (Na+,K+)-adenosinetriphosphatase from dog kidney.

The polypeptide antibiotic duramycin inhibited the (Na+,K+)-adenosinetriphosphatase purified from dog kidney. An analysis of its mode of action revealed that the formation of phosphoenzyme from Pi but not from ATP was inhibited. The rate of dephosphorylation of the phosphoenzyme formed from ATP was markedly reduced. In contrast to quercetin, duramycin did not inhibit K+-dependent p-nitrophenylphosphatase activity. The effect of duramycin was completely reversed by phospholipids.