title: Cathepsin G inactivates human protein S in vitro.
abstract: Human polymorphonuclear leukocyte cathepsin G was used in vitro to digest human protein S. While clotting assays indicated that the proteinase induced a rapid decrease in activity, polyacrylamide gel electrophoresis-sodium dodecyl sulphate indicated the removal of a peptide of low molecular mass product protein S (des 1-40). The loss in activity was the result of cathepsin G cleaving position Phe40-Tyr41 and removing the calcium-binding region. Calcium ions almost totally protected the cofactor from the action of cathepsin G in vitro.
authors.affiliation: Department of Medical Technology, Kuwait University.
authors.forename: P T
authors.initials: PT
authors.lastname: Turkington
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D056649:Cathepsin G; D002403:Cathepsins / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000032:analysis; D017293:Protein S / Q000037:antagonists & inhibitors* / Q000187:drug effects / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012697:Serine Endopeptidases
chemical_list: D010446:Peptide Fragments; D017293:Protein S; D002403:Cathepsins; D012697:Serine Endopeptidases; C534094:CTSG protein, human; D056649:Cathepsin G; D002118:Calcium