DIO-9 AND CHLORHEXIDINE - INHIBITORS OF MEMBRANE-BOUND ATPASE AND OF CATION TRANSPORT IN STREPTOCOCCUS FAECALIS

1. 1. Dio 9, an antibiotic of unknown structure, and the synthetic bis-guanidine Chlorhexidine (1,6-di-4′-chlorophenyldiguanidohexane), inhibit the ATPase associated with isolated protoplast membranes of Streptococcus faecalis. They inhibit both the native, membrane-bound enzyme, and the solubilized protein. The effects of Dio 9 and Chlorhexidine differ in this respect from those of N,N′-dicyclohexylcarbodiimide which was previously found to inhibit only the membrane-bound ATPase. 2. 2. When added to intact cells, Dio 9 and Chlorhexidine inhibit the net uptake of K+ by exchange for Na+ and H+, and also the stimulation of glycolysis associated with K+ uptake. However, they do not inhibit autologous exchange of 42K+ for K+. 3. 3. Dio 9 and Chlorhexidine apparently do not inhibit the generation of ATP via glycolysis. Partial inhibition of glycolysis by these compounds may be a secondary consequence of the inhibition of ATPase. 4. 4. The finding that Dio 9 and Chlorhexidine inhibit both the ATPase and net K+ uptake by S. faecalis supports the hypothesis that the ATPase is involved in ion transport. © 1969.