Typical sensorgrams of NP2 interaction with Factor IXa (A) and Factor IX (B). Different concentrations of FIXa (in nM:a, 20; b, 40; c, 80; d, 160; and e, 320) or FIX (in nM: a, 10; b, 20; c, 40; d, 80; e, 160; f, 320; g, 640) were injected over immobilized NP2 for 180 s. Dissociation of NP2-FIXa and NP2-FIX complex was monitored for 900 s and 800 s, respectively, and a global two-state binding model was used to calculate kinetic parameters. Representative sensorgrams are shown.