Table 3.
Steady state kinetic parameters at 4 °C for WT, W156F, W227F and W155F DaCld in their acidic (top) and alkaline (bottom) forms.
| Enzyme | kcat (× 102 s-1) | KM (mM) | kcat/KM (M-1 s-1) |
|---|---|---|---|
| WTDaClda | 120 ± 5 | 0.24 ± 0.03 | 490 |
| W227Fb | 13 ± 7 | 0.21 ± 0.06 | 61 |
| W156Fb | 21 ± 7 | 0.16 ± 0.03 | 130 |
| W155F | NA | NA | NA |
|
| |||
| WTDaClda | 4.6 | 0.21 | 22 |
| W227Fb | 4.4 ± 0.2 | 0.62 ± 0.12 | 7.1 |
| W156Fb | 4.7 ± 0.4 | 0.13 ± 0.06 | 37 |
| W155F | NA | NA | NA |
a
The WT values are from ref 16.
b
The catalytic activity was measured immediately following dilution of the protein from a ~13 mg/mL and 3.9 mg/mL in 100 mM phosphate buffer for W156F and W227F respectively, pH 6.8 stock into reaction buffer at pH 6 for the acidic measurements and pH 8 for the alkaline. NA: The protein was not reactive toward chlorite.