Figure 3.

PS-direct is enhanced after Zn²⁺ treatment under mildly denaturing conditions. A) MonoQ-purified PS with poor PS-direct was treated with 10 μM Zn²⁺ under the conditions indicated (see Materials and Methods). After dialysis, PS was tested for ability to inhibit generation of thrombin from prothrombin by FXa/FVa. IC₅₀(μM) was determined in each case. PS-direct was expressed as 1/IC₅₀; 1/IC₅₀ ≤ 0.5 was indicated as 0.5. B) Dose response of MonoQ-purified PS with poor PS-direct, with or without treatment with 10 μM Zn²⁺in the presence of 6 M urea or pH 2.7 buffer, followed by dialysis as in Materials and Methods. For comparison, PS-direct of typical IAP PS is also illustrated (dashed line). This experiment was repeated 4 times (Table 2).