title: Association of chicken mitochondrial creatine kinase with the inner mitochondrial membrane.
abstract: The stoichiometry and dissociation constant for the binding of homogeneous chicken heart mitochondrial creatine kinase (MiMi-CK) to mitoplasts was examined under a variety of conditions. Salts and substrates release MiMi-CK from mitoplasts in a manner that suggests an ionic interaction. The binding of MiMi-CK to mitoplasts is competitively inhibited by Adriamycin, suggesting that they compete for the same binding site. Fluorescence measurements also show that Adriamycin binds to MiMi-CK so that the effect of Adriamycin on the binding of MiMi-CK to mitoplasts is not simple. Titrating mitoplasts with homogeneous MiMi-CK at different pH values shows a pH-dependent equilibrium involving a group(s) on either the membrane or the enzyme with a pKa = 6. Extrapolating these titrations to infinite MiMi-CK concentration gives 14.6 IU bound/nmol cytochrome aa3 corresponding to 1.12 mol MiMi-CK/mol cytochrome aa3. Chicken heart mitochondria contain, after isolation, 2.86 +/- 0.42 IU/nmol cytochrome aa3. Titrating respiring mitoplasts with carboxyatractyloside gives at saturation 3.3 mol ADP/ATP translocase/mol cytochrome aa3. Therefore, chicken heart mitoplasts can maximally bind about 1 mol of MiMi-CK per 3 mol translocase; in normal chicken heart mitochondria about 1 mol of MiMi-CK is present per 13 mol translocase.
mesh_terms: D000227:Adenine Nucleotides / Q000378:metabolism; D000818:Animals; D001667:Binding, Competitive; D002645:Chickens; D003402:Creatine Kinase / Q000378:metabolism*; D004317:Doxorubicin / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007425:Intracellular Membranes / Q000378:metabolism; D007700:Kinetics; D008929:Mitochondria, Heart / Q000201:enzymology* / Q000648:ultrastructure; D000226:Mitochondrial ADP, ATP Translocases / Q000378:metabolism; D009994:Osmolar Concentration; D010725:Phosphocreatine / Q000378:metabolism; D012492:Salts / Q000494:pharmacology
chemical_list: D000227:Adenine Nucleotides; D012492:Salts; D010725:Phosphocreatine; D004317:Doxorubicin; D000226:Mitochondrial ADP, ATP Translocases; D003402:Creatine Kinase