Effect of hirugen on FXI activation by α-IIa. (A-C) Western blots of FXI-Ala⁵⁵⁷ (60nM) incubated with 2nM α-IIa in the presence of 1 μg/mL dextran sulfate and (A) vehicle, (B) hirudin (12 units/mL), or (C) hirugen (10μM). The blot was developed with a goat polyclonal antihuman FXI antibody. Positions of zymogen FXI (Z) and the heavy chain (HC) and light chain (LC) of FXIa are shown to the right of the blots. (D) Thrombin generation assay. Thrombin generation was initiated in FXII-deficient plasma with vehicle (−IIa) or 10nM α-IIa in the absence (−hirugen) or presence (+hirugen) of 10μM hirugen. The volumes used here are twice as large as those in Figure 4.