Proactivator-dependent activation of procollagenase induced by treatment with XXXX .

@entity8862 @entity3280 @entity3281 @entity4527 @entity23618 @entity95 @entity141
A new mechanism for activation of the proactivator of procollagenase [Vater, Nagase _ Harris (1983) J. Biol. Chem. 258, 9374-9382] has been found. Collagenolytic and other proteolytic enzyme activities in the medium of cultured @entity95 synovial fibroblasts were found to be activated by a new mechanism: short-term incubation at 37 degrees C performed in the presence of @entity4527 followed by replacement of @entity141 during enzyme assay. The crucial event in procollagenase activation is the production of a functional activator enzyme. Activation of procollagenase in the culture medium did not occur when proactivator was removed by immunoprecipitation. Proteolytic activity of proactivator was fully activated, whereas procollagenase alone could not be activated by the same sequence. @entity4527 treatment of the culture medium at 0 degrees C did not result in enzyme activation if @entity141 was replaced before incubation at 37 degrees C. Certain other bivalent metal ions (e.g. @entity23618 , @entity3280 , @entity8862 and @entity3281 ) could substitute for @entity141 to stabilize the proactivator as a zymogen and therefore prevent the appearance of proteolytic activity in culture medium. Isolation of proactivator and procollagenase from @entity4527 -treated radiolabelled culture medium by immunoprecipitation and subsequent analyses by fluorography revealed that a time-dependent proteolysis of both molecules occurred after replacement of @entity141 and incubation at 37 degrees C. However, comparison of enzyme activity with fluorographic analyses showed that the maximal activation of both enzymes was achieved before any detectable decrease in Mr. The results suggest that the activation of proactivator and the subsequent activation of procollagenase may be initiated by conformational changes in structure of the proactivator molecule produced by removal of stabilizing bivalent metal ions.
