Table II.
Percentage of Free Trypsin Variant after Equilibration with BPTIa
| % Free enzyme after BPTI incubation |
||||||
|---|---|---|---|---|---|---|
| Variant | 10 nM BPTI | 20 nM BPTI | 30 nM BPTI | 50 nM BPTI | 75 nM BPTI | 100 nM BPTI |
| WT | 49 ± 1 | 34 ± 1 | 13.9 ± 0.3 | 2.8 ± 0.1 | 1.05 ± 0.07 | 0.79 ± 0.03 |
| Y39F | 47 ± 2 | 33.0 ± 0.5 | 10.1 ± 0.4 | 1.8 ± 0.3 | 0.7 ± 0.1 | 0.41 ± 0.05 |
| Y39A | 60 ± 1 | 38.9 ± 0.8 | 19.2 ± 0.3 | 3.2 ± 0.1 | 1.45 ± 0.02 | 1.10 ± 0.02 |
| K60V | 47 ± 1 | 12.8 ± 0.4 | – | 0.72 ± 0.09 | 0.29 ± 0.11 | 0.17 ± 0.02 |
| K60A | 43 ± 2 | 10 ± 1 | – | 1.0 ± 0.4 | 0.35 ± 0.08 | 0.24 ± 0.03 |
a
% Free enzyme was determined at 25°C in 50 mM HEPES, 100 mM NaCl, 20 mM CaCl2 (pH 8.0) using the fraction of initial rates [Eq. (2)]. Errors were determined from four trials.