TABLE 3.
Kinetic parameters of wild-type and mutant glutamine synthetases
| Enzyme | Mg2+-dependent biosynthetic reactiona
|
Mn2+-dependent biosynthetic reaction (μmol/min/mg)a | Transferase reaction (μmol/min/mg)a | ||
|---|---|---|---|---|---|
| Km glutamate (mM) | Km ATP (mM) | Vmax (μmol/min/mg) | |||
| Wild type | 27 ± 2.2 | 2.4 ± 0.1 | 2.7 ± 0.2 | 2.4 ± 0.2 | 78 ± 8 |
| E65G | 7.3 ± 0.9 | 3.6 ± 0.4 | 0.35 ± 0.02 | 2.5 ± 0.7 | 73 ± 5 |
| S66P | 130 ± 11 | 23 ± 7 | 2.4 ± 0.2 | 11.0 ± 0.2 | 51 ± 4 |
| M68I | 56 ± 8 | 4.1 ± 0.5 | 2.4 ± 0.2 | 3.9 ± 0.4 | 57 ± 1 |
| H195Y | 30 ± 3 | 7.0 ± 0.6 | 4.7 ± 0.2 | 1.8 ± 0.1 | 43 ± 6 |
| P318S | 3.3 ± 0.5 | 0.81 ± 0.02 | 0.86 ± 0.03 | 0.29 ± 0.02 | 33 ± 3 |
a
Values are the average of at least two determinations ± the sample standard deviation.