Values of the Specificity Constant s = kcat /Km (in mmol/L−1s−1) for the Hydrolysis of Synthetic p-nitroanilide ( p-NA) Substrates by Human APC, Human Thrombin (IIa), and Human Factor Xa
| . | APC . | Thrombin . | Factor Xa . | Specificity (ssub /sS2266) . | Selectivity (SAPC /SIIa) . |
|---|---|---|---|---|---|
| S2266 | 48.2 ± 0.4 | 128 ± 1 | 19.6 ± 0.1 | 1 | 0.38 ± 0.01 |
| H-D-Asp-Arg-Arg-p-NA | 2.1 ± 0.1 | 0.095 ± 0.006 | 6.2 ± 0.9 | 0.04 ± 0.01 | 22 ± 2 |
| H-L-Asp-Arg-Arg-p-NA | 2.4 ± 0.1 | 161 ± 3 | 3.26 ± 0.02 | 0.05 ± 0.01 | 0.015 ± 0.001 |
| H-D-Trp-Arg-Arg-p-NA | 69 ± 1 | 1.8 ± 0.1 | 2.24 ± 0.08 | 1.4 ± 0.1 | 38 ± 1 |
| H-L-Trp-Arg-Arg-p-NA | 1.7 ± 0.1 | 0.147 ± 0.009 | 1.46 ± 0.07 | 0.04 ± 0.01 | 12 ± 1 |
| . | APC . | Thrombin . | Factor Xa . | Specificity (ssub /sS2266) . | Selectivity (SAPC /SIIa) . |
|---|---|---|---|---|---|
| S2266 | 48.2 ± 0.4 | 128 ± 1 | 19.6 ± 0.1 | 1 | 0.38 ± 0.01 |
| H-D-Asp-Arg-Arg-p-NA | 2.1 ± 0.1 | 0.095 ± 0.006 | 6.2 ± 0.9 | 0.04 ± 0.01 | 22 ± 2 |
| H-L-Asp-Arg-Arg-p-NA | 2.4 ± 0.1 | 161 ± 3 | 3.26 ± 0.02 | 0.05 ± 0.01 | 0.015 ± 0.001 |
| H-D-Trp-Arg-Arg-p-NA | 69 ± 1 | 1.8 ± 0.1 | 2.24 ± 0.08 | 1.4 ± 0.1 | 38 ± 1 |
| H-L-Trp-Arg-Arg-p-NA | 1.7 ± 0.1 | 0.147 ± 0.009 | 1.46 ± 0.07 | 0.04 ± 0.01 | 12 ± 1 |
Data were derived from analysis of progress curves under experimental conditions of 5 mmol/L Tris, 0.1% PEG, 200 mmol/L NaCl, pH 8.0, 25°C. The specificity of the substrate refers to the value of s for APC compared with that obtained with S2266. The selectivity of the substrate refers to the value of s for APC relative to that of thrombin.