Table 2. Kinetic parameters for activation of GD-PC by thrombin in the presence of cofactors.
| kcat, mol·min-1·mol-1 | Km, μM | |
|---|---|---|
| Thrombin | ||
| GD-PC, TM456, Ca2+ | 13.8 ± 1.2 | 6.8 ± 0.3 |
| GD-PC, TM456, EDTA | ND | ND |
| GD-PC, dextran sulfate, Ca2+ | 0.59 ± 0.02 | 4.9 ± 0.5 |
| R35E thrombin | ||
| GD-PC, TM456, Ca2+ | 14.0 ± 0.7 | 4.5 ± 0.9 |
| GD-PC, TM456, EDTA | 55.5 ± 2.3 | 13.0 ± 1.1 |
| GD-PC, EDTA | 61.4 ± 2.2 | 15.8 ± 1.0 |
| GD-PC, dextran sulfate, Ca2+ | 3.7 ± 0.3 | 5.0 ± 0.9 |
| R35A thrombin | ||
| GD-PC, TM456, Ca2+ | 14.2 ± 0.2 | 4.8 ± 0.2 |
| GD-PC, TM456, EDTA | ND | ND |
The concentration dependence of the initial rate of GD-PC (0.2-22 μM) activation by wild-type, R35E, and R35A thrombins (1 nM each) in the presence of TM456 (500 nM) or dextran sulfate (25 μg/ml) was determined as described in Methods. ND, not determinable.