Rates and stoichiometries of factor Xa and thrombin inhibition (I = 0.15)
Antithrombin . | Factor Xa kapp . | SI . | kapp × SI . | Thrombin kapp . | SI . | kapp × SI . |
|---|---|---|---|---|---|---|
| Plasma α | (3.8 ± 0.2) × 103 | 1.0 ± 0.1 | 3.8 × 103 | (8.4 ± 0.2) × 103 | 1.0 ± 0.1 | 8.4 × 103 |
| +Penta | (7.1 ± 0.2) × 105 | 1.1 ± 0.2 | 7.8 × 105 | ND | 1.1 ± 0.1 | ND |
| +FLH | (1.4 ± 0.1) × 106 | 1.1 ± 0.2 | 1.8 × 106 | (1.1 ± 0.1) × 107 | 1.2 ± 0.2 | 1.3 × 107 |
| +Mixed | ND | ND | ND | ND | 1.3 ± 0.1 | ND |
| S137A | (3.8 ± 0.2) × 103 | 1.0 ± 0.1 | 3.8 × 103 | (8.2 ± 0.3) × 103 | 1.1 ± 0.2 | 9.0 × 103 |
| +Penta | (7.6 ± 0.2) × 105 | 1.2 ± 0.1 | 9.1 × 105 | ND | 1.1 ± 0.1 | ND |
| +FLH | (1.1 ± 0.2) × 106 | 1.3 ± 0.2 | 1.4 × 106 | (1.3 ± 0.2) × 107 | 1.4 ± 0.1 | 1.8 × 107 |
| +Mixed | ND | ND | ND | ND | 2.0 ± 0.2 | ND |
| A384S | (5.2 ± 0.2) × 103 | 1.3 ± 0.1 | 6.8 × 103 | (9.5 ± 0.2) × 103 | 1.2 ± 0.1 | 11.4 × 103 |
| +Penta | (6.7 ± 0.3) × 105 | 1.3 ± 0.2 | 8.7 × 105 | ND | 1.3 ± 0.1 | ND |
| +FLH | (1.6 ± 0.2) × 105 | 2.8 ± 0.1 | 4.5 × 105 | (2.3 ± 0.3) × 105 | 7.3 ± 0.2 | 1.7 × 106 |
| +Mixed | ND | ND | ND | ND | 10.0 ± 0.1 | ND |
Antithrombin . | Factor Xa kapp . | SI . | kapp × SI . | Thrombin kapp . | SI . | kapp × SI . |
|---|---|---|---|---|---|---|
| Plasma α | (3.8 ± 0.2) × 103 | 1.0 ± 0.1 | 3.8 × 103 | (8.4 ± 0.2) × 103 | 1.0 ± 0.1 | 8.4 × 103 |
| +Penta | (7.1 ± 0.2) × 105 | 1.1 ± 0.2 | 7.8 × 105 | ND | 1.1 ± 0.1 | ND |
| +FLH | (1.4 ± 0.1) × 106 | 1.1 ± 0.2 | 1.8 × 106 | (1.1 ± 0.1) × 107 | 1.2 ± 0.2 | 1.3 × 107 |
| +Mixed | ND | ND | ND | ND | 1.3 ± 0.1 | ND |
| S137A | (3.8 ± 0.2) × 103 | 1.0 ± 0.1 | 3.8 × 103 | (8.2 ± 0.3) × 103 | 1.1 ± 0.2 | 9.0 × 103 |
| +Penta | (7.6 ± 0.2) × 105 | 1.2 ± 0.1 | 9.1 × 105 | ND | 1.1 ± 0.1 | ND |
| +FLH | (1.1 ± 0.2) × 106 | 1.3 ± 0.2 | 1.4 × 106 | (1.3 ± 0.2) × 107 | 1.4 ± 0.1 | 1.8 × 107 |
| +Mixed | ND | ND | ND | ND | 2.0 ± 0.2 | ND |
| A384S | (5.2 ± 0.2) × 103 | 1.3 ± 0.1 | 6.8 × 103 | (9.5 ± 0.2) × 103 | 1.2 ± 0.1 | 11.4 × 103 |
| +Penta | (6.7 ± 0.3) × 105 | 1.3 ± 0.2 | 8.7 × 105 | ND | 1.3 ± 0.1 | ND |
| +FLH | (1.6 ± 0.2) × 105 | 2.8 ± 0.1 | 4.5 × 105 | (2.3 ± 0.3) × 105 | 7.3 ± 0.2 | 1.7 × 106 |
| +Mixed | ND | ND | ND | ND | 10.0 ± 0.1 | ND |
Rate constants are in units of M−1s−1. Penta indicates the physiological pentasaccharide; FLH, full-length heparin; Mixed, a synthetic heparin with a pentasaccharide followed by a nonsulphated linker and a thrombin-binding hexasaccharide; and ND, not done.