INHIBITION OF K+ FLUX INTO RAT-LIVER MITOCHONDRIA BY DICYCLOHEXYLCARBODIIMIDE

Dicyclohexylcarbodiimide (DCCD), which has been reported to react covalently with a subunit of the ATP synthase complex involved in proton translocation, decreases the rate of unidirectional K+ flux into rat liver mitochondria in the presence of the respiratory substrate, succinate. In contrast, oligomycin does not affect the rate of K+ influx. At concentrations which completely block ADP-stimulated respiration, DCCD increases the apparent Km for K+ of the K+ transport mechanism, while having little effect on the Vmax of K+ influx. Inhibition of K+ influx by DCCD is observed over the whole pH range tested from 6.8 to 8.0. A slight, but reproducible, decrease in the pH-dependence of K+ influx is observed in the presence of DCCD. © 1979 Academic Press, Inc. All rights of reproduction in any form reserved.