title: Heart mitochondria in physiological salt solution: not ionic strength but salt composition is important for association of creatine kinase with the inner membrane surface.
abstract: In physiological salt solution (PSS) which mimicks the cardiac cells cytoplasm and contains 120 mM K-MES, 10 mM NaCl, 20 mM imidazole, pH 7.2, 20 mM taurine, 15 mM creatine, 15 mM Na2phosphocreatine, 5 mM Na2ATP, 8 mM MgCl2, 5 mM K2HPO4, 3 mM glutamate, 3 mM malate, 0.5 mM dithiothreitol and 10 mg/ml of bovine serum albumine both isolated mitochondria and intracellular structures in skinned fibers stay intact. In PSS mitochondrial creatine kinase remains firmly attached to the inner membrane surface. CKmi-mi is extracted from cardiac mitoplasts in 0.125 M KCl solution, but addition of 10 mM sodium borate to this KCl solution completely inhibits dissociation of CKmi-mi. Therefore, not ionic strength but ion composition is important for association of CKmi-mi with mitochondrial membrane. Functional and structural studies using antibodies against CKmi-mi showed that in PSS CKmi-mi is bound to the inner mitochondrial membrane in spatially close relationship to adenine nucleotide translocase (ANT). Thus, under physiological conditions CKmi-mi is structurally and functionally coupled to ANT in cardiac mitochondria and functions to catalyze almost complete utilization of mitochondrial ATP for aerobic phosphocreatine synthesis.
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D003402:Creatine Kinase / Q000378:metabolism*; D007425:Intracellular Membranes / Q000201:enzymology; D007527:Isoenzymes; D008854:Microscopy, Electron; D008929:Mitochondria, Heart / Q000201:enzymology* / Q000648:ultrastructure; D009994:Osmolar Concentration; D010101:Oxygen Consumption; D011189:Potassium Chloride / Q000494:pharmacology; D012965:Sodium Chloride / Q000502:physiology*
chemical_list: D007527:Isoenzymes; D012965:Sodium Chloride; D000244:Adenosine Diphosphate; D011189:Potassium Chloride; D000255:Adenosine Triphosphate; D003402:Creatine Kinase