Partial Resolution of the Enzymes Catalyzing Oxidative Phosphorylation

Abstract 1. The observation that low concentrations of oligomycin stimulated oxidative phosphorylation in A-particles has been confirmed and extended. 2. Oligomycin was found to stimulate each of the three sites of oxidative phosphorylation, but optimal phosphorylation rates were obtained only when coupling factors were added as well. The P:O ratio with succinate was raised from 0.06 with particles alone to over 1.5 when coupling factors 1, 2, and 4, oligomycin, and thioglycerol were added. 3. The relatively high rates of oxidative phosphorylation in the presence of oligomycin or of any pair of coupling factors suggested that residual amounts of coupling factors were present in A-particles. 4. This suggestion was borne out by studies with an antibody against coupling factor 1, which inhibited ATPase, 32Pi-ATP exchange, and oxidative phosphorylation at all three sites in submitochondrial particles. The stimulation of oxidative phosphorylation by oligomycin in A-particles was abolished by the antibody against F1.