FXI activation by recombinant thrombins. (A-E) Western blot of FXI-Ala⁵⁵⁷ (100nM) incubated with (A) vehicle, or 25nM (B) α-IIa-WT, (C) rMz-IIa, (D) α-IIa-Glu⁶⁸, or (E) α-IIa-Glu⁷⁰ at 37°C. FXI was detected with a polyclonal goat antihuman FXI antibody. Positions of zymogen FXI (Z) and the heavy chain (HC) and light chain (LC) of FXIa are shown to the left of the blots. Incubation times in hours are indicated above panel A. (F-G) Thrombin generation initiated in FXII-deficient plasma by 10nM (F) α-IIa-WT or rMz-IIa, or (G) α-IIa-Glu⁶⁸ and α-IIa-Glu⁷⁰.