METAL-DEPENDENT NEUTRAL PROTEOGLYCANASE ACTIVITY FROM MONOLAYER-CULTURED LAPINE ARTICULAR CHONDROCYTES

  • 1 January 1979
    • journal article
    • research article
    • Vol. 93  (6) , 1018-1030
Abstract
Neutral proteoglycanase and other protease activity from cellular and CM [harvested culture median] fractions of monolayer-cultured rabbit articular chondrocytes were studied. The cellular fraction comprising soluble cytoplasmic enzymes possessed concentration-dependent elastase-like esterase activity and activity against trypsin and chymotrypsin synthetic substrates but had little caseinase activity. The 20% (NH4)SO4 precipitate of CM possessed more neutral caseinase activity than the 60% (NH4)2SO4 precipitate and the bulk of activity against the synthetic substrates. Activity against bovine nasal septum PG [proteoglycan] was present in these fractions. Both the 20 and 60% (NH4)2SO4 fractions reduced the viscosity and the .hivin.S [average wt sedimentation coefficient] of the PG substrate. This activity was incompletely inhibited by preincubation with either 5 mM o-phenanthroline or 10 mM EDTA, indicating that it was partially metal-dependent. The cellular fraction activity was partially inhibited by o-phenanthroline but more so by EDTA. Apparently chondrocytes synthesized and secreted into the culture medium neutral proteoglycanase(s) capable of initiating degradation of PG derived from the neutral pH cartilage matrix. The proteoglycanase enzyme(s) may occur in multiple forms.