TABLE 2.
Kinetic parameters of wild-type NgaP and mutants
The reaction mixture containing different amounts of pNP-β-GalNAc (3–250 nmol) was incubated with 0.5 milliunits of the enzyme at 37 °C for 30 min in 100 μl of 25 mm sodium acetate buffer (pH 6.0). Values are the means of triplicate determinations. ND, no products were detected.
| Enzyme | Km | kcat | kcat/Km | Relative kcat/Km |
|---|---|---|---|---|
| mm | s−1 | s−1mm−1 | ||
| WT | 0.35 | 7.3 | 21.0 | 100 |
| D607E | 1.74 | 0.10 | 0.06 | 0.28 |
| D607N | ND | ND | ND | ND |
| E608D | 0.20 | 0.38 | 1.9 | 9.0 |
| E608Q | 0.09 | 0.08 | 0.88 | 4.2 |