Abstract
A chymotrypsin-like enzyme with substrate specificity resembling pancreatic α-chymotrypsin was isolated in small quantities from human polymorphonuclear leucocytes and compared with pancreatic chymotrypsin. The enzyme had activity against a variety of chymotrypsin substrates containing tyrosin residues. It was inhibited by DFP and by TPCK suggesting the presence of serine and histidine residues in the active center. However, the inhibition by TPCK was slower for the leucocyte enzyme than for pancreatic chymotrypsin. The behaviour of the enzyme in three different separation systems suggested that the molecular weight of the leucocyte enzyme and of its subunits obtained after treatment with DTT was about twice as great as for pancreatic chymotrypsin. The enzyme was localized in the cytosol and no association with the leucocyte granules could be demonstrated. The physiological role of “big leucocyte chymotrypsin” is at the present time unknown. It may be involved in phagocytosis or in the immunological response of the cell.
DFP = Diisopropylphosphofluoride
TPCK=L-1-tosylamide-2-phenylethychloromethylketone
DTT=Dithioerythrite
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Gerber, A., Carson, J. & Hadorn, B. “Big chymotrypsin” from human leucocytes. Pediatr Res 8, 905 (1974). https://doi.org/10.1203/00006450-197411000-00056
Issue Date:
DOI: https://doi.org/10.1203/00006450-197411000-00056