title: Purification and characterization of an inhibitor of calcium-activated neutral protease from rabbit skeletal muscle.
abstract: An endogenous inhibitor of calcium-activated neutral protease was purified to homogeneity from rabbit skeletal muscle using ion-exchange chromatography on DEAE-cellulose and QAE-Sephadex A-50 columns, chromatofocusing, and hydrophobic interaction chromatography on a phenyl-Sepharose CL-4B column. The purified inhibitor was shown to be a dimer of identical subunits and each subunit has a molecular weight of about 34,000. This inhibitor was remarkably thermo- and acid-stable. It was specific for calcium-activated neutral protease and had no effect on any other protease examined (trypsin, papain, alpha-chymotrypsin, bromelain, etc.). It is demonstrated that the inhibition is due to the formation of stoichiometric complex between two enzyme molecules and one inhibitor molecule.
mesh_terms: D000818:Animals; D002154:Calpain; D010450:Endopeptidases / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000302:isolation & purification*; D007700:Kinetics; D009132:Muscles / Q000201:enzymology*; D011480:Protease Inhibitors; D011817:Rabbits
chemical_list: D004791:Enzyme Inhibitors; D011480:Protease Inhibitors; D010450:Endopeptidases; D002154:Calpain