title: Only one of the two interconvertible forms of mitochondrial creatine kinase binds to heart mitoplasts.
abstract: When analyzed by cellulose acetate electrophoresis, solubilized pig or rabbit heart mitochondrial creatine kinase is shown to exist under two distinct forms. The less cathodic one (form 1) is a dimer and the other having a higher cathodic mobility (form 2) has a molecular weight of about 350,000. The latter form can be converted into the former by incubation at alkaline pH or when the enzyme forms a reactive or an abortive complex with its substrates. This conversion is a reversible phenomenon and is not due to proteolysis. When rabbit heart mitoplasts are treated with the creatine kinase releasing agents, the enzyme is always solubilized as its form 2 and conversion to form 1, when it occurs, always take place after solubilization. Form 2 is also the only form which can be bound to pig or rabbit mitoplasts. Thus form 2 may be the actual form associated with heart mitochondria in vivo.
mesh_terms: D000818:Animals; D003402:Creatine Kinase / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes; D008929:Mitochondria, Heart / Q000201:enzymology*; D008970:Molecular Weight; D009206:Myocardium / Q000166:cytology*; D011817:Rabbits; D013552:Swine
chemical_list: D007527:Isoenzymes; D003402:Creatine Kinase