title: The mitochondrial localization of coproporphyrinogen III oxidase.
abstract: The location of coproporphyrinogen III oxidase in mitochondria was studied in rat liver by using the digitonin method or hypo-osmotic media for fractionation. The enzyme was found in the intermembrane space with a fraction loosely bound to the inner membrane. This fraction was released by washing the inner-membrane-matrix complex with alkaline solutions or solutions of high ionic strength. The enzyme in both fractions had the same Km (0.16 micrometer) for coproporphyrinogen III. When incubation was performed in a medium that avoided destruction of enzyme membrane binding, a dramatic increase in activity was observed after sonication of whole mitochondria or of the inner-membrane-matrix complex.
mesh_terms: D000818:Animals; D003304:Coproporphyrinogen Oxidase / Q000378:metabolism*; D004072:Digitonin / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000201:enzymology; D008297:Male; D008930:Mitochondria, Liver / Q000187:drug effects / Q000201:enzymology*; D010088:Oxidoreductases / Q000378:metabolism*; D051381:Rats; D013010:Sonication
chemical_list: D010088:Oxidoreductases; D003304:Coproporphyrinogen Oxidase; D004072:Digitonin