Table 1.
Inhibitory parameters and conformational switch rate of α1AT variants
| Residue 117 | SI* | kapp,† 105 M−1⋅s−1 | SINBD‡ | kobs,§ s−1 |
|---|---|---|---|---|
| Gly (wt) | 1.66 ± 0.06 | 3.86 ± 0.26 | 1.71 ± 0.05 | 2.05 |
| Ala | 1.70 ± 0.03 | 4.10 ± 0.41 | ND | ND |
| Val | 1.91 ± 0.05 | 3.85 ± 0.26 | 1.85 ± 0.07 | 2.00 |
| Leu | 2.21 ± 0.09 | 4.07 ± 0.21 | ND | ND |
| Ile | 2.50 ± 0.08 | 4.20 ± 0.23 | 2.49 ± 0.08 | 1.93 |
| Phe | 3.99 ± 0.12 | 4.80 ± 0.38 | 3.60 ± 0.21 | 1.65 |
ND, not determined; wt, wild type.
*
The number of moles of α1AT required to completely inhibit 1 mole of PPE.
†
Apparent second-order association rate constant of α1AT with PPE, which corresponds to k1k2/k−1 in Scheme 1 (20).
‡
Stoichiometry of inhibition of the NBD-labeled α1AT variants carrying C232S and A350C mutations.
§
Pseudo-first-order rates for the increase in NBD fluorescence. The values are the limiting rates obtained by fitting the measured rates at various concentrations of PPE to a hyperbolic function.