TABLE 2.
Real inhibition constants (Ki) of rShPI-1A wild type and K13L variant for serine proteases
Ki values are reported in nm. NI, no inhibition was detected even at Io/Eo molar ratio of 170 incubated for 30 min. Real Ki values were calculated according to the equation Ki = Ki app/([S0]/(Km) + 1) considering the substrate concentration [So] and the Km values. The following substrates were used for: trypsin, Bz-Arg-pNA (41); HNE, MeO-Suc-Ala-Ala-Pro-Val-pNA (42); chymotrypsin, Suc-Ala-Ala-Pro-Phe-pNA (40); and PPE, Suc-Ala-Ala-Ala-pNA (42).
| Enzyme | rShPI-1A wt | rShPI-1/K13L |
|---|---|---|
| Trypsin | 2.7 ± 0.3 | 320 ± 35 |
| Chymotrypsin | 14.8 ± 1.5 | 4.5 ± 0.5 |
| Human neutrophilic elastase | 23.5 ± 2.0 | 1.3 ± 0.4 |
| Porcine pancreatic elastase | NI | 12.0 ± 2.6 |