Targeting the GPIbα binding site of thrombin to simultaneously induce dual anticoagulant and antiplatelet effects.

Mehta AY, Thakkar JN, Mohammed BM, Martin EJ, Brophy DF, Kishimoto T, Desai UR. (2014) Targeting the GPIbα binding site of thrombin to simultaneously induce dual anticoagulant and antiplatelet effects. J Med Chem. 57(7):3030-9. PMID: 24635452.

Abstract

Exosite 2 of human thrombin contributes to two opposing pathways, the anticoagulant pathway and the platelet aggregation pathway. We reasoned that an exosite 2 directed allosteric thrombin inhibitor should simultaneously induce anticoagulant and antiplatelet effects. To assess this, we synthesized SbO4L based on the sulfated tyrosine-containing sequence of GPIbα. SbO4L was synthesized in three simple steps in high yield and found to be a highly selective, direct inhibitor of thrombin. Michelis-Menten kinetic studies indicated a noncompetitive mechanism of inhibition. Competitive inhibition studies suggested ideal competition with heparin and glycoprotein Ibα, as predicted. Studies with site-directed mutants of thrombin indicated that SbO4L binds to Arg233, Lys235, and Lys236 of exosite 2. SbO4L prevented thrombin-mediated platelet activation and aggregation as expected on the basis of competition with GPIbα. SbO4L presents a novel paradigm of simultaneous dual anticoagulant and antiplatelet effects achieved through the GPIbα binding site of thrombin.

Link to journal: http://pubs.acs.org/journal/jmcmar