Back to Search Start Over

Chemically modified thrombin and anhydrothrombin that differentiate macromolecular substrates of thrombin

Authors :
S. Wakabayashi
K. Hosokawa
T. Ohnishi
A. Kawakami
Takehiko Koide
Source :
Journal of Thrombosis and Haemostasis. 3:2703-2711
Publication Year :
2005
Publisher :
Elsevier BV, 2005.

Abstract

Summary. Background: Thrombin is a primary inducer of thrombus formation by activations of coagulation cascade and platelet aggregation. Hitherto, several types of thrombin inhibitors have been developed for therapeutic purpose. Objectives: We prepared modified thrombin (M-thrombin) and modified anhydrothrombin (M-anhydrothrombin) by chemical modification of carboxyl groups of thrombin and anhydrothrombin, respectively, to present a new strategy for a potent antiplatelet–anticoagulant agent and new tools for investigation of thrombin functions. Results: M-anhydrothrombin retained high affinity for factor VIII (FVIII), but demonstrated lower affinity than anhydrothrombin for fibrinogen and factor V (FV). Both M-anhydrothrombin and anhydrothrombin prolonged activated partial thromboplastin time (APTT) without affecting prothrombin time, and M-anhydrothrombin prolonged APTT much more than anhydrothrombin. M-anhydrothrombin also retained affinity for the recombinant extracellular domain peptide of protease-activated receptor 1 (PAR1). M-thrombin exhibited marginal clotting activity (4% of thrombin), but induced platelet aggregation in platelet-rich plasma without forming a fibrin clot, which was completely suppressed by anti-PAR1 antibody (ATAP2) and by M-anhydrothrombin, but not by anhydrothrombin. These results indicate that M-thrombin induced platelet aggregation through the activation of PAR1, and M-anhydrothrombin inhibited this process completely. In contrast, neither M-anhydrothrombin nor anhydrothrombin apparently inhibited thrombin-induced platelet aggregation. Only in the presence of the Gly-Pro-Arg-Pro (GPRP) peptide that inhibits polymerization of fibrin, M-anhydrothrombin completely inhibited thrombin-induced platelet aggregation. Conclusion: M-thrombin is PAR1-specific and M-anhydrothrombin is FVIII- and PAR1-specific derivatives, and thereby, are new tools as specific agonist and antagonist, respectively, of PAR1. Furthermore, M-anhydrothrombin may be an attractive model for development of a potent anticoagulant–antiplatelet agent.

Details

ISSN :
15387836
Volume :
3
Database :
OpenAIRE
Journal :
Journal of Thrombosis and Haemostasis
Accession number :
edsair.doi.dedup.....d8fc34a180842cb5d241558689718b52
Full Text :
https://doi.org/10.1111/j.1538-7836.2005.01637.x