FIGURE 1.

Binding of A2 and a3A3C1C2 to FIXa by SPR. Biotinylated FPR-FIXa was immobilized on a streptavidin chip and the binding kinetics with the FVIII A2 subunit (A) and a3A3C1C2 (B) were monitored at a flow rate of 10 μl/min for a 3-min association with subunit followed by a 3-min dissociation after return to buffer flow. Representative curves correspond to subunit concentrations of (1) 12.5 nm, (2) 6.25 nm, (3) 3.13 nm, (4) 1.56 nm, and (5) 0.78 nm with data represented by the bold black line, and the fitted curve using the two-state binding model shown by the black dashed line. A representative fit using the single-site binding model is shown by the gray dotted line for the 12.5 nm subunit concentrations.