FIGURE 8.

Effect of competitors on the binding of ¹²⁵I-HRG or ¹²⁵I-YPRck-thrombin to γ_A/γ_A- or γ_A/γ′-fibrin clots. A, ¹²⁵I-HRG (20 nm) was added to microcentrifuge tubes containing 2 μm γ_A/γ_A-fibrinogen (triangles) or γ_A/γ′-fibrinogen (circles) in the presence of FPRck-thrombin (0–10 μm). B, ¹²⁵I-YPRck-thrombin (20 nm) was added to microcentrifuge tubes containing 2 μm γ_A/γ_A-fibrinogen (triangles) or 0.25 μm γ_A/γ′-fibrinogen (circles) in the presence of HRG (0–2 μm). In both experiments 2 mm CaCl₂ plus 20 μm ZnCl₂ were present and clotting was initiated with 10 nm thrombin. After incubation at 23 °C for 45 min, fibrin was pelleted by centrifugation, and free ¹²⁵I-HRG or ¹²⁵I-YPRck-thrombin in the supernatant was used to calculate the bound fraction. The percent of fibrin-bound ¹²⁵I-HRG or ¹²⁵I-YPRck-thrombin is plotted versus the FPRck-thrombin or HRG concentration, respectively. The symbols represent the mean ± S.D. of two experiments, each performed in duplicate, whereas the lines represent nonlinear regression analyses of the data.