Inhibition of FXa by Pefabloc. The initial velocity (V) of
peptidyl substrate hydrolysis (S-2765; 100 μm for wild-type rFXa
or 500 μm for mutant rFXa) catalyzed by free FXa (A) (3
nm wild-type rFXa; 10 nm mutant rFXa) or prothrombinase
(B) (60 μm PCPS and 20 or 100 nm FVa for
wild-type rFXa and mutant rFXa, respectively) was determined at increasing
concentrations of Pefabloc. For visual purposes, the data are normalized to
V/Vo × 100, where V is the
velocity at a given concentration of Pefabloc and Vo is
the starting initial velocity. ▪, PDFXa; ○, rFXa; ▴,
rFXaI16L; and ⋄, rFXaV17A. The data are
representative of two to three similar experiments.