Table I.
Vmax and Ea of PPDK M. × giganteus and maize from crude leaf extracts (n = 5 replicate plants) and from E. coli (n = 3 independent transformations) into which the genes from each species had been cloned
Values given are means (and ses) and their units are given at the end of the table. Leaf and recombinant protein extracts were made as described in “Materials and Methods.”
| Species | Growth Temperature |
Vmax,ppdka
|
Ea (kJ mol−1)b
|
||
|---|---|---|---|---|---|
| 25°C | 15°C | 6°C–18°C (6°C–15°C) | 18°C–28°C (18°C–28°C) | ||
| M. × giganteus crude leaf extract | 25°C | 39.2 (1.5) | 14.2 (0.9) | 93.5 (6.4) | 63.2 (3.8) |
| 14°C | 43.5 (1.3) | 18.3 (0.7) | 79.1 (5.2) | 57.3 (3.2) | |
| Maize crude leaf extract | 25°C | 46.1 (0.9) | 17.1 (1.6) | 106.2 (8.9) | 58.1 (2.9) |
| 14°C | 18.0 (1.2) | 5.3 (0.9) | 145.8 (9.5) | 71.9 (4.2) | |
| M. × giganteus recombinant PPDK | – | 7.3 (0.5) | 3.3 (0.4) | 115.7 (6.2) | 51.6 (2.9) |
| Maize recombinant PPDK | – | 7.6 (0.4) | 3.1 (0.3) | 114.3 (5.8) | 52.1 (3.6) |
a
The units for Vmax,ppdk of PPDK in crude leaf extract are μmol s−1 m−2 and for recombinant PPDK μmol min−1 mg−1.
b
Ea for PPDK in crude leaf extract was calculated from slopes of Arrhenius plots at low (6°C–18°C) and high (18°C–28°C) temperature ranges; for recombinant PPDK at low (6°C–15°C) and high (18°C–28°C) temperature ranges.