Table 1. Substrate Specificity of MOMT4 on Different Phenolics.
| Substrate | Specific Activity (nmol mg−1 min−1) | Km (µM) | Vmax (nmol mg−1 min−1) | kcat/Km (M−1 s−1) |
|---|---|---|---|---|
| Coniferyl alcohol | 66.8 ± 0.7 (100)a | 192.6 ± 24.5b | 793.0 ± 3.4b | 2738.7b |
| Sinapyl alcohol | 79.6 ± 0.9 (119) | 68.1 ± 11.1b | 407.5 ± 16.5b | 3999.3b |
| Coniferaldehyde | 28.7 ± 0.8 (43) | 6.4 ± 0.5 | 22.0 ± 0.4 | 2291.8 |
| Sinapaldehyde | 14.6 ± 0.5 (22) | 3.0 ± 0.5 | 9.3 ± 0.2 | 2099.3 |
| P-coumaryl alcohol | 5.5 ± 0.1 (8.2) | 190.3 ± 12.0 | 13.7 ± 0.4 | 48.0 |
| P-coumaraldehyde | 1.9 ± 0.0 (2.8) | 171.0 ± 20.6 | 3.8 ± 0.2 | 14.6 |
| Caffeyl alcohol | 1.7 ± 0.0 (2.5) | |||
| Ferulic acid | 3.6 ± 0.0 (5) | 533.2 ± 32.3 | 14.2 ± 0.4 | 17.8 |
| Sinapic acid | 1.8 ± 0.0 (3) | 503.6 ± 12.2 | 20.3 ± 0.2 | 26.9 |
| Feruloyl CoA | NDc | |||
| Sinapoyl CoA | ND | |||
| Sinapoyl glucose | ND | |||
| Sinapoyl malate | ND |
The relative activity was measured from the reaction at 30°C for 30 min. Kinetic parameters were obtained from the reactions at 30°C for 10 min. The data represent the mean ± se of two replicates.
a
Data in parentheses represent relative activity.
b
Data obtained from radioactive assays.
c
ND, not detectable; no data shown indicates the kinetics were not tested.