title: Rat liver pyruvate carboxylase. V. Reversible dissociation by chloride salts of monovalent cations.
abstract: Rat liver mitochondrial pyruvate carboxylase is inactivated reversibly and converted to protomers by incubation at 0 degrees in the presence of high concentrations of Cl- salts of monovalent cations. This inactivation, as well as restoration of enzymic activity, is dependent on temperature, protein concentration, and salt concentration. MgCl2 or sucrose are relatively effective in preventing inactivation and are required along with EDTA for reactivation. The enzyme can be dissociated reversibly from the native tetramer into enzymically active dimers and protomers by incubation with 30 to 100 mM ammonium chloride at 0 degrees and pH 7.0 Isolated monomeric enzyme is activated by acetyl-CoA and appears to show sigmoid saturation curves with respect to acetyl-CoA binding. Biphasic double reciprocal plots are obtained with respect to pyruvate as previously shown for the tetramer.
mesh_terms: D000105:Acetyl Coenzyme A; D000643:Ammonium Chloride / Q000494:pharmacology; D000818:Animals; D001665:Binding Sites; D002499:Centrifugation, Density Gradient; D002712:Chlorides / Q000494:pharmacology; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D004492:Edetic Acid / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D007700:Kinetics; D008094:Lithium / Q000494:pharmacology; D046911:Macromolecular Substances; D008274:Magnesium / Q000494:pharmacology; D008854:Microscopy, Electron; D008930:Mitochondria, Liver / Q000201:enzymology*; D011189:Potassium Chloride / Q000494:pharmacology; D011485:Protein Binding; D011766:Pyruvate Carboxylase / Q000302:isolation & purification / Q000378:metabolism; D051381:Rats; D012965:Sodium Chloride / Q000494:pharmacology; D013395:Sucrose / Q000494:pharmacology; D013696:Temperature
chemical_list: D002712:Chlorides; D046911:Macromolecular Substances; D000643:Ammonium Chloride; D012965:Sodium Chloride; D013395:Sucrose; D011189:Potassium Chloride; D000105:Acetyl Coenzyme A; D008094:Lithium; D004492:Edetic Acid; D011766:Pyruvate Carboxylase; D008274:Magnesium