Thrombin is inactivated by mast cell secretory granule chymase.
In a recent paper we demonstrated that cultures of murine adherent peritoneal cells expressed cell surface-associated serine protease activity that specifically inactivated thrombin by cleaving the enzyme into defined proteolytic fragments (Pejler, G., and Seljelid, R. (1992) J. Biol. Chem. 267, 3136-3142). In the present report, the purification and further characterization of the thrombin-inactivating serine protease is described. The serine protease is shown to be expressed by mast cells. Purification of the thrombin-inactivating serine protease by a combination of anion-exchange chromatography and Superdex 75 chromatography showed that the enzyme had an apparent molecular mass of 28 kDa. N-terminal sequence analysis of the purified protein demonstrated 100% identity of the thrombin-inactivating serine protease with the secretory granule chymases: murine mast cell protease 3 and murine mast cell protease 4. The serine protease showed chymotrypsin-like substrate specificity. The thrombin-inactivating activity was markedly enhanced by optimal concentrations of heparin.
Department of Veterinary Medical Chemistry, Biomedical Center, Uppsala, Sweden.
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Pejler
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Karlström
D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D053818:Chymases; D003594:Cytoplasmic Granules / Q000201:enzymology*; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006493:Heparin / Q000494:pharmacology; D007700:Kinetics; D008407:Mast Cells / Q000201:enzymology*; D051379:Mice; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000302:isolation & purification; D011480:Protease Inhibitors / Q000494:pharmacology; D012697:Serine Endopeptidases / Q000302:isolation & purification / Q000378:metabolism*; D013917:Thrombin / Q000037:antagonists & inhibitors / Q000378:metabolism*
D010446:Peptide Fragments; D011480:Protease Inhibitors; D006493:Heparin; D012697:Serine Endopeptidases; D053818:Chymases; D013917:Thrombin