Some properties of neutral proteinases from lysosomes of rabbit polymorphonuclear leukocytes
Britz, ML and Lowther, DA, Some properties of neutral proteinases from lysosomes of rabbit polymorphonuclear leukocytes, Australian Journal of Experimental Biology and Medical Science, 59, (Feb) pp. 63-75. ISSN 0004-945X (1981) [Refereed Article]
Neutral proteinases capable of degrading proteoglycan were found in lysosomes of rabbit polymorphonuclear leucocytes extracted with 0.01 M citric acid. Esterase activity against an elastase substrate was also present but chymotrypsin- and trypsin-like activities were not detected; azocasein-degrading activity was poor. Proteoglycanase activity was stimulated by high concentrations of salts (0.2 M KCl) and divalent cations (Ca, Mg, Mn, Zn) but was inhibited by Cu ++ . Elastase activity was also stimulated by high ionic strength buffers and KCl, but not as much by divalent cations, and was inhibited by Cu ++ . Proteoglycanase in crude extracts was inhibited by EDTA, phenylmethanesulphonylfluoride (Pms-F), cell cytosol, α 1 -antitrypsin, gold thiomalate and N-acetyl-di-L-alanyl-L-prolyl-L-valine chloromethyl ketone (AAAPVCK). Partial inhibition by N-α-p-tosyl-L-lysine chloromethyl ketone (TLCK) and L-1-tosylamide-2-phenylethyl chloromethyl ketone (TPCK) occurred. Elastase adsorbed to CM-cellulose and was eluted by 0.6-0.7 M NaCl; a metallo-proteinase failed to adsorb completely but was retarded by the CM-cellulose. Isoelectric focusing showed that the major proteinases had pI's of 5.5, 8.5 and 9.1; the activity with pI 8.5 was a metalloproteinase, and the pI 9.1 activity was an elastase. The apparent molecular weight of the elastase, determined on Sephadex G-100, was 8,000 to 11,000 daltons.