Heparin-catalyzed factor Xa or prothrombinase inhibition by the mutant of antithrombin
| . | − Cofactor . | + PC/PS . | + PC/PS + Va . |
|---|---|---|---|
| H5 | (7.6 ± 0.9) × 104 | (3.2 ± 0.1) × 104 | < 101 |
| H26 | (2.9 ± 0.3) × 105 | (1.2 ± 0.1) × 105 | ∼2 × 102 |
| H70 | (7.3 ± 0.3) × 106 | (5.1 ± 0.8) × 106 | ∼3 × 103 |
| UFH | (3.0 ± 0.6) × 106 | (1.4 ± 0.1) × 106 | ∼3 × 103 |
| . | − Cofactor . | + PC/PS . | + PC/PS + Va . |
|---|---|---|---|
| H5 | (7.6 ± 0.9) × 104 | (3.2 ± 0.1) × 104 | < 101 |
| H26 | (2.9 ± 0.3) × 105 | (1.2 ± 0.1) × 105 | ∼2 × 102 |
| H70 | (7.3 ± 0.3) × 106 | (5.1 ± 0.8) × 106 | ∼3 × 103 |
| UFH | (3.0 ± 0.6) × 106 | (1.4 ± 0.1) × 106 | ∼3 × 103 |
Apparent second-order rate constants (M−1second−1) for antithrombin inhibition of a fully assembled prothrombinase complex was measured from the time-dependent inhibition of thrombin generation using S2238, as described in “Materials and methods.” Concentrations of the reaction components in TBS buffer containing 1 mg/mL BSA, 0.1% PEG 8000, and 2.5 mM CaCl2were human factor Xa, 1 nM in the absence and 0.2 pM in the presence of factor Va; PC/PS vesicles, 50 μM; human factor Va, 5 nM; human prothrombin, 1.5 μM; antithrombin mutant, 2.3 μM; H5, 25 to 1000 nM; H26, 5 to 200 nM; H70, 1 to 100 nM; UFH, 1 to 100 nM.
For abbreviations, see Table 2.