title: Recombinant human protein C: comparative functional studies with human plasma protein C.
abstract: Protein C (PC) is the central protein in a major antithrombotic regulatory mechanism. Hereditary deficiencies of PC are associated with thrombosis. Therapeutic PC replacement may be an important treatment if pure functional human protein C is available in sufficient quantity. Human PC has been produced on a commercial scale using recombinant techniques. To study the functional properties of recombinant protein C (r-PC), we undertook a comparative investigation of the basic properties of r-PC and plasma protein C (n-PC). Both were isolated by immunopurification methods. Protac C activation proceeded at the same rate and kinetics for both forms. With thrombin-thrombomodulin (T-TM) activation, r-PC is significantly better than the activation of n-PC (for r-PC: Kcat/Km = 378 vs. n-PC: Kcat/Km = 35). No difference in the anticoagulant (aPTT prolongation) or profibrinolytic activities (inactivation of PAI-1 and PAI-3) were observed between activated r-PC and n-PC. Based on these functional studies, recombinant protein C has similar properties to the plasma form of protein C. However, T-TM activation of r-PC occurs faster than the n-PC. The mechanism is unknown, but may be due to the presence of larger amounts of single chain protein C which exists in a conformation more rapidly activated by the T-TM complex.
authors.affiliation: Lab Service, VA Medical Center, Denver CO 80220.
authors.forename: R M
authors.initials: RM
authors.lastname: Madden
authors.forename: C
authors.initials: C
authors.lastname: Oppenheimer
authors.forename: R
authors.initials: R
authors.lastname: Wydro
authors.forename: R A
authors.initials: RA
authors.lastname: Marlar
mesh_terms: D001780:Blood Coagulation Tests; D004789:Enzyme Activation; D005342:Fibrinolysis / Q000187:drug effects; D006801:Humans; D011486:Protein C / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology; D011487:Protein Conformation; D011956:Receptors, Cell Surface / Q000378:metabolism; D018179:Receptors, Thrombin; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology; D013917:Thrombin / Q000378:metabolism
chemical_list: D011486:Protein C; D011956:Receptors, Cell Surface; D018179:Receptors, Thrombin; D011994:Recombinant Proteins; D013917:Thrombin