Table 1.
Summary of PpHCT kinetic parameters
| Substrates |
K m (mM) | k cat (s−1) | k cat/Km (s−1.M−1) | |
|---|---|---|---|---|
| Fixed | Variable | |||
| p-coumaroyl-CoA | Threonate | 17.2 (14.9–19.9) | 0.16 (0.15–0.17) | 9 |
| Shikimate | 0.22 (0.17–0.29) | 5.1 (4.8–5.4) | 23,005 | |
| Quinate | 9.4 (6.7–13.7) | 3.5 (3.0–4.2) | 368 | |
| Threonate | p-coumaroyl-CoA | 0.43 (0.27–0.76) | 0.18 (0.14–0.25) | 407 |
| Shikimate | p-coumaroyl-CoA | 0.06 (0.03–0.10) | 17.0 (14.1–20.7) | 283,333 |
Enzyme affinity (Km) and velocity (kcat) constants were determined from PpHCT activity saturation curves, based on nonlinear Michaelis–Menten regression (see the “Materials and methods” section; Supplemental Figure S5). Results are the means of three independent enzyme reactions; 95% confidence intervals (profile likelihood) are provided within brackets.