Effect of leaf temperature on the activities of PPDK, PEP carboxylase, and Rubisco
| Leaf Temperature | PPDK1-a | PEP Carboxylase | Rubisco | ||
|---|---|---|---|---|---|
| Vmax1-b | Malate sensitivity1-c | Initial1-d | Total1-e | ||
| °C | μmol m−2s−1 | % Inhibition | μmol m−2 s−1 | ||
| 28 | 15.7 ± 1 | 308 ± 14 | 51 ± 3 | 32 ± 2 | 31 ± 1 |
| 40 | – | – | 59 ± 1 | – | – |
| 42.5 | – | – | 63 ± 3 | – | – |
| 45 | 13.4 ± 1 | 295 ± 10 | 66 ± 2 | 6 ± 1 | 29 ± 3 |
All assays were conducted at 30°C. Values represent the mean ±se of four replicates for PPDK and PEP carboxylase, and three replicates for Rubisco.
↵F1-a PPDK assayed under conditions to preserve the in vivo activation state.
↵F1-b Assayed under optimal conditions to indicate total potential activity.
↵F1-c Assayed using limiting substrate in the presence or absence of 0.5 mm l-malate; indicates the in vivo activation state.
↵F1-d Initial activity measured immediately after extraction; indicates in vivo activity.
↵F1-e Total activity measured after incubating in CO2 and Mg2+ to fully activate Rubisco.