Human serum alpha 1-antichymotrypsin is an inhibitor of pancreatic elastases.
Incubation of human serum alpha 1-antichymotrypsin with human pancreatic elastase 2 or porcine pancreatic elastase results in the complete inhibition of each enzyme as determined by spectrophotometric assays. alpha 1-Antichymotrypsin reacts much more rapidly with the human than with the porcine enzyme. The inhibitor: enzyme molar ratio, required to obtain full inhibition of enzymatic activity, is equal to 1.25/1 when alpha 1-antichymotrypsin reacts with human pancreatic elastase 2 while it is markedly higher with porcine pancreatic elastase (5.5/1). Patterns obtained by SDS/polyacrylamide gel electrophoresis of the reaction products show the formation with both enzymes of an equimolar complex (Mr near 77 000) and the release of a fragment migrating as a peptide of Mr near 5000. Moreover a free proteolytically modified form of alpha 1-antichymotrypsin, electrophoretically identical with that obtained in the reaction with cathepsin G or bovine chymotrypsin, is produced in the reaction with each elastase but in a much greater amount when alpha 1-antichymotrypsin reacts with porcine elastase than with human elastase. As a consequence of our findings, the specificity of alpha 1-antichymotrypsin, so far limited to the inhibition of chymotrypsin-like enzymes from pancreas and leukocyte origin, has to be extended to the two pancreatic elastases investigated in this work. A contribution of alpha 1-antichymotrypsin to the regulatory balance between plasma inhibitors and human pancreatic elastase 2 in pancreatic diseases is suggested.
D000818:Animals; D002918:Chymotrypsin / Q000037:antagonists & inhibitors* / Q000097:blood; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D010179:Pancreas / Q000201:enzymology*; D010196:Pancreatic Elastase / Q000037:antagonists & inhibitors*; D013053:Spectrophotometry / Q000379:methods; D013552:Swine; D000514:alpha 1-Antichymotrypsin
D000514:alpha 1-Antichymotrypsin; D002918:Chymotrypsin; D010196:Pancreatic Elastase