Effect of mutant ₂AP on cross-linking of native ₂AP to fibrin in plasma. Plasma samples containing a trace amount of ¹²⁵I-native ₂AP or ¹²⁵I-mutant ₂AP were clotted in the presence of specified concentrations of mutant ₂AP. After a 30-minute incubation, the amount of cross-linked native ₂AP (○) or mutant ₂AP (▵) was determined in triplicate as described in Materials and Methods.