title: Calcium-activated neutral protease from human placenta: purification and characterization.
abstract: Calcium-activated neutral protease (CANP) has been purified from the human placenta by chromatographic procedures. The purified enzyme is a heterodimer with one subunit of mol. wt 70 000 and another of mol.wt 32 000. It is a thiol protease, active at pH 7.5 at 30 degrees C in the presence of calcium. Half-maximal activation of the enzyme occurred with 800 microM Ca2+.Zn2+ (2 mM), ethylenediaminetetraacetic acid (EDTA)(5 mM) and ethyleneglycol-bis-N,N,N',N'-tetraacetic acid (EGTA)(2 mM) inhibited the enzyme, while Mg2+ (0.5 mM to 5 mM) had no effect on the enzyme in the presence of calcium. Mn2+ and Ca2+ activated the enzyme synergistically. CANP coexists with its endogenous inhibitor in the human placenta. The inhibitor is a protein, inactivated by trypsin and unaffected by RNase, DNase, acid and heat treatments; it inhibits the enzyme probably by interacting with the enzyme molecule itself rather than by sequestering calcium ions.
mesh_terms: D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002122:Calcium Chloride; D004228:Dithionitrobenzoic Acid / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000302:isolation & purification* / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D006801:Humans; D007461:Iodoacetates / Q000494:pharmacology; D019807:Iodoacetic Acid; D008623:Mercaptoethanol; D008970:Molecular Weight; D015260:Neprilysin; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy; D011480:Protease Inhibitors
chemical_list: D007461:Iodoacetates; D011480:Protease Inhibitors; D004533:Egtazic Acid; D008623:Mercaptoethanol; D004228:Dithionitrobenzoic Acid; D004492:Edetic Acid; D010450:Endopeptidases; D015260:Neprilysin; D002122:Calcium Chloride; D002118:Calcium; D019807:Iodoacetic Acid