Respiration-driven Proton Transport in Submitochondrial Particles

Abstract

Abstract 1. The maximal H+:O ratios of proton transport in highly resolved submitochondrial particles prepared by sonication of bovine heart mitochondria in the presence of ammonia and exposed sequentially to Sephadex and urea (ASU particles) in the presence of oligomycin were found to be 6, 4, and 2 during the oxidation of NADH, succinate, or N-methylphenazonium methosulfate, respectively. A pH dependence for the H+:O ratio was observed with optimal ratios at pH 6.0 to 6.5. 2. Comparison of the effects of an uncoupler (p-trifluoromethoxycarbonyl cyanide phenylhydrazone) and of oligo-mycin on proton transport and on respiratory control in ASU particles showed that the effect of these compounds on the respiratory rate could be accounted for by their effect on the proton permeability of the particles. 3. The external and internal buffering powers of ASU particles were calculated from the extent of overshoot of pH change on addition of acid or alkali. 4. Coupling factors of oxidative phosphorylation, F1 and oligomycin sensitivity-conferring protein, decreased the proton permeability of ASU particles and allowed proton transport to be observed in the absence of oligomycin.