TABLE 1.
Kinetic constants and stoichiometries of inhibition for reactions of furin with wild-type and variant forms of serpin B8 and α1PDX
Association rate constants (ka) and stoichiometries of inhibition (SI) for serpin-furin reactions were measured at pH 7.5, 25 °C, as described in the legend to Fig. 1 and under “Experimental Procedures.” Errors represent S.E. from linear regression fits of data. The SI for the serpin B8 R342A mutant was assumed to be 1 based on the absence of detectable cleaved serpin product in the reaction by SDS-PAGE analysis (Fig. 2).
| Inhibitor variant | ka | SI |
|---|---|---|
| m−1 s−1 | ||
| Serpin B8-5S | 2.4 ± 0.3 × 105 | 1.5 ± 0.1 |
| Serpin B8-5S5A | 2.3 ± 0.2 × 105 | 2.2 ± 0.1 |
| Serpin B8-5S-R342A | 7.6 ± 0.5 × 104 | 1 |
| α1PDX | 1.1 ± 0.1 × 106 | 1.1 ± 0.1 |
| α1PDX-serpin B8 P6–P1 | 2.5 ± 0.3 × 106 | 1.3 ± 0.1 |
| α1PDX-serpin B8 P1′–P5′ | 5.5 ± 0.8 × 104 | 1.2 ± 0.1 |
| α1PDX-serpin B8 P6–P5′ | 1.1 ± 0.1 × 105 | 1.4 ± 0.1 |
| α1PDX-YE | 2.1 ± 0.3 × 105 | 1.9 ± 0.1 |
| α1PDX-serpin B8 P6–P5′–YE | 1.5 ± 0.2 × 103 | 1.3 ± 0.2 |