Autolytic activation of calcium-activated neutral protease

Degradation of vimentin by native low calcium ion-requiring protease (mu CANP) was compared to that by autodigested mu CANP. On activation with 5 mM barium ions, a lag time was observed for the case of native mu CANP. This provides direct evidence that native mu CANP is inactive as a protease and must be autolyzed to be activated. Most of the protease activity can be accounted for by autodigested mu CANP with a 76 K polypeptide but another species with 50 K polypeptide may also be active.