TABLE 5.
Enzymatic constants for wild-type and mutant GS proteins
The kinetic constants were determined for the Mg2+-dependent biosynthetic reaction. All assays were performed at least twice. The uncertainty is the S.E. from the nonlinear regression analysis of the data.
| Enzyme |
Km |
Vmax | |||
|---|---|---|---|---|---|
| Glutamate | ATP | Ammonium | Hydroxylamine | ||
| mm | μmol/min/mg | ||||
| Wild type | 27 ± 2 | 2.4 ± 0.1 | 0.18 ± 0.03 | 0.83 ± 0.07 | 3.7 ± 0.2 |
| R62A | 14 ± 2 | 2.3 ± 0.3 | 0.34 ± 0.05 | 1.4 ± 0.2 | 2.9 ± 0.1 |
| E304A | 3.4 ± 0.2 | 1.2 ± 0.1 | 32 ± 2 | 0.68 ± 0.09 | 1.3 ± 0.1 |