Table 2.
Apparent kinetic parameters of ZmPEPC-C4 wildtype and mutant S100K enzymes
| Parametera | Wildtype | S100K |
|---|---|---|
| Saturation by Gly | ||
| v0 | 4.5 | 8.5 |
| vamax | 24.3 ± 0.3 | NE |
| A0.5 | 2.0 ± 0.1 | NE |
| Saturation by Gly + 20 mm malate | ||
| v0 | 0.02 | 2.9 |
| vamax | 11.5 ± 0.2 | NE |
| A0.5 | 16.3 ± 0.6 | NE |
| Saturation by l-Ala | ||
| v0 | 4.8 | 8.3 |
| vamax | 23.4 ± 0.3 | NE |
| A0.5 | 5.9 ± 0.3 | NE |
| Saturation by l-Ser | ||
| v0 | 5.8 | 10.1 |
| vamax | 16.4 ± 0.6 | NE |
| A0.5 | 6.2 ± 0.9 | NE |
a Values ±S.D. were estimated by the best fit to Equation 1, fixing the h value to 1 and v0 to the experimentally determined values. Velocities (v0 and va max) are given as units/mg of protein, and A0.5 is given as mm. Assays were carried out at pH 7.3, 0.4 mm free Mg2+, 0.1 mm bicarbonate, and 3 mm total PEP. NE, values not estimated due to the absence of activation.