title: Identification of calcium-dependent proteolytic activity in human polymorphonuclear leukocytes.
abstract: Calcium-dependent proteolytic activity has been identified in extracts of human polymorphonuclear leukocytes. The activity is most pronounced in the neutral pH range with a pH optimum of 7.3. Maximal activation of the protease occurs at a free calcium concentration of 190 microM; it is half maximal at 91 microM. This protease activity is strongly inhibited by aprotinin and phenylmethylsulfonyl fluoride (PMSF) and more weakly inhibited by antipain, leupeptin, and o-phenanthroline. The protease is not activated by calmodulin nor is it inhibited by the calmodulin antagonist trifluoperazine. Gel filtration suggests a molecular weight of 74,100 daltons.
mesh_terms: D002118:Calcium / Q000494:pharmacology*; D002147:Calmodulin / Q000494:pharmacology; D003600:Cytosol / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008970:Molecular Weight; D009247:NADH, NADPH Oxidoreductases / Q000097:blood; D019255:NADPH Oxidases; D009504:Neutrophils / Q000201:enzymology*; D010447:Peptide Hydrolases / Q000097:blood*; D011480:Protease Inhibitors / Q000494:pharmacology
chemical_list: D002147:Calmodulin; D011480:Protease Inhibitors; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; D010447:Peptide Hydrolases; D002118:Calcium