Effect of rifampicin derivatives on the ion compartmentation of biological membranes.

Based on the experimental results that 3-formyl rifamycin SV acts as an uncoupler in vitro on rat liver mitochondria, the effect of some rifampicin derivatives on the K+ and H+ compartmentation of biological membranes was examined to obtain a chemiosmotic hypothesis for oxidative phosphorylation. The K+ release from mitochondria was remarkably stimulated by 3-formyl rifamycin SV in accordance with uncoupling of the oxidative phosphorylation. 3-Formyl rifamycin SV also stimulated the K+ release from red blood cells, though its action was not as effective as in mitochondria. It can be suggested that 3-formyl rifamycin SV interacts with biological membranes, causing a change in permeability to ions, especially of K+ and H+ through the mitochondrial membrane, resulting in uncoupling of the oxidative phosphorylation.