Apparent Stoichiometry for Protease Inhibition by PAI-1
| Protease . | 1.5 h . | 2.5 h . | 4.3 h . | 18 h . | +Heparin . | +Vitronectin . |
|---|---|---|---|---|---|---|
| Thrombin | 3.2 | 3.1 | 2.8 | 3.0 | 7.1 | 5.1 |
| Thrombin-VR1 | 2.3 | 2.9 | 2.3 | 2.3 | 6.6 | 7.4 |
| t-PA | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 |
| Protease . | 1.5 h . | 2.5 h . | 4.3 h . | 18 h . | +Heparin . | +Vitronectin . |
|---|---|---|---|---|---|---|
| Thrombin | 3.2 | 3.1 | 2.8 | 3.0 | 7.1 | 5.1 |
| Thrombin-VR1 | 2.3 | 2.9 | 2.3 | 2.3 | 6.6 | 7.4 |
| t-PA | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 |
The apparent stoichiometries were determined by titration at 37°C at least in duplicate as described under “Experimental Procedures.” Indicated are results obtained at different time points and, when indicated, in the presence of either an optimal heparin concentration (ie, 1 U/mL in case of thrombin (502.5 nmol/L) inhibition, and 0.5 U/mL in case of thrombin-VR1 (20 nmol/L inhibition), or 200 nmol/L vitronectin.