Immunological comparison of the b and c1 cytochromes from bovine heart mitochondria and the photosynthetic bacterium Rhodopseudomonas sphaeroides R-26.
Antibodies against cytochromes b and c1 of bovine heart mitochondria and the photosynthetic bacterium, Rhodopseudomonas sphaeroides R-26, were raised in rabbits. The purified antibodies showed high titers against their respective antigens in enzyme-linked immunosorbent assays. Less than 15% cross-reactivity between the mitochondrial and bacterial cytochromes was detected. Although antibodies against mitochondrial cytochrome b did not inhibit the mitochondrial cytochrome b-c1 complex, a 70% inhibition was obtained when these antibodies were incubated with delipidated mitochondrial cytochrome b-c1 complex prior to reconstitution with phospholipids indicating that the catalytic site(s) of mitochondrial cytochrome b are masked by phospholipids. On the other hand, antibodies against bacterial cytochrome b showed significant inhibition of the intact bacterial cytochrome b-c1 complex, indicating that some of the catalytic site epitopes of bacterial cytochrome b are exposed to the hydrophilic environment. Similar to antibodies against mitochondrial cytochrome b, antibodies against bacterial cytochrome b inhibited 50% activity of the mitochondrial cytochrome b-c1 complex only when they were incubated with the delipidated mitochondrial cytochrome b-c1 complex prior to reconstitution with phospholipids, indicating that the common epitopes between the cytochromes b are masked by phospholipids. Antibodies against mitochondrial and bacterial cytochromes c1 completely inhibited their respective cytochrome b-c1 complexes but no cross-immunoinhibition was observed. However, when antibodies against bacterial cytochrome c1 were incubated with the delipidated mitochondrial cytochrome b-c1 complex before reconstitution with phospholipids, a 65% inhibition was observed, indicating that the common epitopes between the cytochromes c1 were also somewhat masked by phospholipids. Antibodies against mitochondrial cytochrome c1 inhibited 70% of the succinate oxidase activity in the intact mitochondria preparation, but no inhibition was observed in submitochondrial particles, indicating that some mitochondrial cytochrome c1 epitopes are exposed to the cytoplasmic side.
D000818:Animals; D000936:Antigen-Antibody Complex; D002417:Cattle; D003573:Cytochrome b Group / Q000276:immunology / Q000378:metabolism*; D003574:Cytochrome c Group / Q000031:analogs & derivatives*; D003575:Cytochromes c1 / Q000276:immunology / Q000378:metabolism*; D007106:Immune Sera; D007700:Kinetics; D008929:Mitochondria, Heart / Q000378:metabolism*; D010788:Photosynthesis; D012242:Rhodobacter sphaeroides / Q000378:metabolism*; D013045:Species Specificity
D000936:Antigen-Antibody Complex; D003573:Cytochrome b Group; D003574:Cytochrome c Group; D007106:Immune Sera; D003575:Cytochromes c1