Potent Trivalent Inhibitors of Thrombin through Hybridization of Salivary Sulfopeptides from Hematophagous Arthropods

Abstract

Blood feeding arthropods,such as leeches,ticks, flies and mosquitoes,p rovide ap rivileged source of peptidic anticoagulant molecules.T hese primarily operate through inhibition of the central coagulation protease thrombin by binding to the active site and either exosite Io re xosite II. Herein, we describe the rational design of an ovel class of trivalent thrombin inhibitors that simultaneously blockb oth exosites as well as the active site.These engineered hybrids were synthesized using tandem diselenide-selenoester ligation (DSL) and native chemical ligation (NCL) reactions in onepot. The most potent trivalent inhibitors possessed femtomolar inhibition constants against a-thrombin and were selective over related coagulation proteases.Alead hybrid inhibitor possessed potent anticoagulant activity,blockade of both thrombin generation and platelet aggregation in vitro and efficacy in am urine thrombosis model at 1mgkg À1 .T he rational engineering approach described here lays the foundation for the development of potent and selective inhibitors for ar ange of other enzymatic targets that possess multiple sites for the disruption of protein-protein interactions,i na ddition to an active site.