TABLE 2.
Comparison of kinetics of the WT and E228K mutant PhyA phytasesa
| pH | Phytase | Km (μM) | Vmax (μmol m−1 mg−1) | kcat (m−1) | kcat/Km (m−1 μM−1) |
|---|---|---|---|---|---|
| 5.5 | WT | 177.3 ± 22.4 | 94.7 ± 5.4 | 7,385.3 ± 421.1 | 41.64 |
| E228K | 38.6 ± 13.2* | 34.5 ± 3.9* | 2,690.2 ± 304.1* | 69.71* | |
| 3.5 | WT | 321.9 ± 37.9 | 33.8 ± 5.4 | 2,638.4 ± 421.1 | 8.20 |
| E228K | 227.8 ± 18.5* | 62.1 ± 3.9* | 4,844.3 ± 304.1* | 21.27* |
a
Enzymatic reactions (n = 3) were conducted at 37°C in 0.2 M glycine-HCl buffer for pH 3.5 and in 0.2 M citrate buffer for pH 5.5 using various sodium phytate concentrations (0.1 to 10 Km) and 100 mU phytase (purified) per ml reaction mixture. An asterisk indicates a difference (P < 0.05) from the WT.