Interaction of anti-iron-sulfur protein and anti-ubiquinone binding protein antibodies with complex III of beef heart mitochondria

Ubiquinol-cytochrome c reductase activity of Complex III was substantially inhibited by anti-iron-sulfur protein antibody, whereas it was not affected by anti-ubiquinone binding protein antibody. Enzyme-linked immunosorbent assay indicated that anti-ubiquinone binding protein antibody do not bind to the complex, but that it binds to Complex III of which iron-sulfur protein and phospholipids have been depleted. These results indicate that some of the antigenic sites of the iron-sulfur protein are located on the surface of Complex III, while the antigenic sites of the ubiquinone binding protein are inaccessible to antibody owing to the interaction with iron-sulfur protein and/or phospholipids in the complex.