HUMAN PANCREATIC PROENZYMES ARE ACTIVATED AT DIFFERENT RATES INVITRO

The rates of activation of procolipase, prophospholipase (proPLA2), ch ymotrypsinogen, and trypsinogen were studied after incubation of human pancreatic juice with porcine enterokinase in vitro. Under the condit ions chosen procolipase was fully activated within 10 min of incubatio n. Full activation of phospholipase (PLA2) Was seen within 15 min, whe reas complete activation of chymotrypsin and trypsin was not seen unti l after 30 to 60 min, respectively. The different proenzymes probably differ in their suitability as substrates for trypsin. A physiologic c onsequence of a differentiated activation of the pancreatic proenzymes in vivo could be a delayed proteolytic degradation of the lipolytic e nzymes in the intestine.