Progress curve amidolytic assays measuring inhibition of PPE or plasmin by FFP and S/D plasma. Reactions were initiated by the addition of either 0.4 μmol/L PPE or 0.2 μmol/L plasmin to a mixture of plasma and 500 μmol/L of the appropriate substrate. (A) Reactions initiated with PPE: (1) noninhibited control; (2) S/D plasma; (3) 1:2 dilution of FFP; (4) FFP; (5) S/D plasma after addition of 12.5 μmol/L purified antitrypsin. (B) Reactions initiated with plasmin: (1) noninhibited control; (2) S/D plasma; (3) 1:10 dilution of FFP; (4) FFP; (5) S/D plasma after addition of 0.9 μmol/L purified antiplasmin.