Diamide blocks H+ conductance in mitochondrial H+‐ATPase by oxidizing FB dithiol

Abstract
Effects of diamide on proton conductance of electron transport particles (ETPH), purified H+‐ATPase (F1–F0), F0 of the H+‐ATPase from beef heart mitochondria and binding of cadmium (109Cd) to the H+‐ATPase have been examined in the present paper. When ETPH and purified H+‐ATPase are treated with 1 mM diamide, ATP‐dependent generation of membrane potential, monitored by the absorbance change produced by the redistribution of oxonol VI, is consistantly inhibited. Diamide also blocks passive H+ conductance driven by a K+ diffusion potential in the membrane sector, F0 of H+‐ATPase. Furthermore, diamide treatment drastically reduces the binding of 109Cd2+ to H+‐ATPase, showing competition for the FB dithiol group.