Human serum procarboxypeptidase A.
Zymogen activation is an important biochemical control process and has important physiological and pathological implications. We have simultaneously measured both procarboxypeptidase A, the enzyme precursor, and carboxypeptidase A, its active product, in serum by using an affinity resin and the synthetic peptide substrate N-(2-furanacryloyl)-L-phenylalanyl-L-phenylalanine. Serum procarboxypeptidase A is activated by trypsin, chymotrypsin, plasmin, subtilisin, or urokinase but not by thrombin or enteropeptidase. The molecular weight of the precursor is approximately 5000-10 000 greater than that of the active product. Both enzyme and precursor increase in serum in the course of pancreatic inflammation, but the degree of activation can vary up to 2000-fold, independent of the amount of precursor present. The existence of this pancreatic proteolytic precursor in serum opens new avenues for the investigation of zymogen activation and its regulation.
D002268:Carboxypeptidases / Q000097:blood*; D043422:Carboxypeptidases A; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000097:blood*; D006801:Humans; D010447:Peptide Hydrolases / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism
D004792:Enzyme Precursors; D002268:Carboxypeptidases; D010447:Peptide Hydrolases; D043422:Carboxypeptidases A; D014357:Trypsin