Thrombin mutant W215A/E217A acts as a platelet GPIb antagonist

Arterioscler Thromb Vasc Biol. 2008 Feb;28(2):329-34. doi: 10.1161/ATVBAHA.107.156273. Epub 2007 Oct 25.


Objective: Thrombin containing the mutations Trp215Ala and Glu217Ala (WE) selectively activates protein C and has potent antithrombotic effects in primates. The aim of this study was to delineate the molecular mechanism of direct WE-platelet interactions under static and shear conditions.

Methods and results: Purified platelets under static conditions bound and spread on immobilized wild-type but not WE thrombin. In PPACK-anticoagulated blood under shear flow conditions, platelets tethered and rolled on both wild-type and WE thrombin, and these interactions were abrogated by the presence of a glycoprotein Ib (GPIb)-blocking antibody. Platelet deposition on collagen was blocked in the presence of WE, but not wild-type thrombin or prothrombin. WE also abrogated platelet tethering and rolling on immobilized von Willebrand factor in whole blood under shear flow.

Conclusions: These observations demonstrate that the thrombin mutant WE, while not activating platelets, retains the ability to interact with platelets through GPIb, and inhibits GPIb-dependent binding to von Willebrand factor-collagen under shear.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Animals
  • Blood Coagulation / physiology*
  • Blood Platelets / physiology
  • Enzymes, Immobilized
  • Humans
  • Mice
  • Mutant Proteins / physiology*
  • Platelet Activation / physiology*
  • Platelet Adhesiveness / physiology
  • Platelet Glycoprotein GPIb-IX Complex / physiology*
  • Recombinant Proteins
  • Rheology
  • Thrombin / chemistry
  • Thrombin / genetics*
  • Thrombin / physiology*
  • Thrombosis / physiopathology
  • von Willebrand Factor / physiology


  • Enzymes, Immobilized
  • Mutant Proteins
  • Platelet Glycoprotein GPIb-IX Complex
  • Recombinant Proteins
  • glycocalicin
  • von Willebrand Factor
  • Thrombin