Human CELA1 has pancreatic elastase-like activity

CELA3A and CELA3B are the primary elastases secreted by the human pancreas that are digestive enzymes and are markers for pancreatic exocrine insufficiency. CELA1, another family member, is not expressed in the human pancreas but has been detected in the mouse lung and human keratinocytes. However, the enzymatic activity and mechanism of function of human CELA1 has not been previously demonstrated. Here, we show using purified, recombinant pro-hCELA1, that it is activated by trypsin and has pancreatic elastase-like activity. We show that pro-hCELA1 cleavage by trypsin is blocked by aprotinin. We have determined the enzyme kinetics of the active fraction of recombinant hCELA1 and show that it follows steady-state kinetics with a higher substrate affinity than commercial porcine pancreatic elastase.