title: Purification of a Ca2+-activated protease from rat erythrocytes and its possible effect on pyruvate kinase in vivo.
abstract: A Ca2+-activated protease with [32P]phosphopyruvate kinase as substrate was purified to about 50% from rat erythrocytes. The purification involved chromatography on Sepharose/Sephadex gels, DEAE-cellulose and (NH4)2SO4 precipitation. The protease required 3.3 mM Ca2+ for full activity. When pyruvate kinase (ATP: pyruvate 2-O-phosphotransferase, EC 2.7.1.40) was purified from erythrocytes incubated with  [32P]phosphate it contained 0.5 mol [32P]phosphate/mol enzyme subunit. When 3.3 mM Ca2+ were added at hemolysis this incorporation decreased. The possible importance of this Ca2+-activated protease for the regulation of pyruvate kinase in erythrocytes is discussed.
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002154:Calpain; D010450:Endopeptidases / Q000097:blood*; D004789:Enzyme Activation; D004912:Erythrocytes / Q000201:enzymology*; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D046911:Macromolecular Substances; D010447:Peptide Hydrolases / Q000302:isolation & purification / Q000494:pharmacology; D010710:Phosphates / Q000378:metabolism; D011770:Pyruvate Kinase / Q000097:blood*; D051381:Rats
chemical_list: D046911:Macromolecular Substances; D010710:Phosphates; D011770:Pyruvate Kinase; D010450:Endopeptidases; D010447:Peptide Hydrolases; D002154:Calpain; D002118:Calcium