Figure 4.

PS-direct is lost or regained with loss or regain of Zn²⁺. PS that contained Zn²⁺ and had good PS-direct (lighter bars) and Zn²⁺-deficient PS with weak PS-direct (darker bars) were each treated for 10 min with 10 mM of the Zn²⁺-chelator, o-phenanthroline. Half of each treated PS was then dialyzed against TBS (middle set of bars), and the other half of each was dialyzed against TBS-10 μM Zn²⁺ (last set of bars). Each was then dialyzed twice against TBS. PS antigen level was determined, and several concentrations were tested for ability to inhibit generation of thrombin from prothrombin by FXa/FVa. Reciprocal of IC₅₀ is indicated. Data from 2 experiments performed on different days were combined.