Effect of the membranes. Binding of proTWT (green circles), proTCC (blue circles), and proTY93A (red circles) to PS-containing liposomes monitored by surface plasmon resonance. (A) Representative sensograms for proTCC (0.125-2 μM, 1:2 dilution). (B) Plot of response units (RUs) as a function of prothrombin concentration. Solid lines were drawn according to a simple binding equation with best-fit parameters: proTWT, RU₀ = 0, RU_∞ = 773 ± 14, dissociation constants (K_d) = 270 ± 15 nM; proTCC, RU₀ = 0, RU_∞ = 822 ± 14, K_d = 329 ± 10 nM; proTY93A, RU₀ = 0, RU_∞ = 581 ± 14, K_d = 370 ± 21nM. (C) Competitive inhibition of proTWT, proTCC, and proTY93A at 5 μM in the absence or presence of liposomes (100 μM).