Table 3.
Kinetic Parameters for Carbamylation of Ile16 in FXIaa
| no pAB |
saturating pAB |
|||
|---|---|---|---|---|
| protein | rate constant (M−1 min−1) |
fold- changeb |
rate constant (M−1 min−1) |
fold- changec |
| FXIaWT | 15.4 ± 0.9 | 1.0b | 6.8 ± 0.5 | 1.0b |
| FXIaG193A | 35.4 ± 1.6 | 2.3 | 6.4 ± 0.8 | 0.9 |
| FXIaG193V | 49.9 ± 1.7 | 3.2 | 6.3 ± 1.0 | 0.9 |
| FXIaG193D | 38.5 ± 1.4 | 2.5 | 4.3 ± 0.6 | 0.6 |
| FXIaG193E | 51.5 ± 1.3 | 4.0 | 7.9 ± 1.0 | 1.2 |
| FXIaG193K | 20.8 ± 1.2 | 1.4 | 5.4 ± 0.3 | 0.8 |
a
The rates of carbamylation of the free amino group of Ile16 of FXIa were measured over a period of 5 h as described under Experimental Procedures. Upon carbamylation, FXIa becomes inactive and cannot hydrolyze a synthetic substrate. Aliquots of each reaction, run either in the presence or in the absence of saturating amounts of pAB, were removed every 30 min and assayed for residual FXIa activity. Results are averages for two experiments.
b
Fold-change is compared to the carbamylation rate for FXIaWT in the absence of pAB.
c
Fold-change is compared to the carbamylation rate for FXIaWT in the presence of pAB.