Table 3.
Kinetic Parameters of Vv GT6a
| Substrate | kcat (s−1) | Km (μM) | kcat/Km (s−1 μM−1) |
| GlcT Activity | |||
| Quercetin | 0.760 ± 0.023 | 9.24 ± 1.20 | 0.082 |
| Kaempferol | 0.473 ± 0.013 | 4.11 ± 0.47 | 0.115 |
| Isorhamnetin | 0.273 ± 0.017 | 7.43 ± 1.62 | 0.037 |
| UDP-Glcb | 28.5 ± 3.9 | 0.027 | |
| GalT Activity | |||
| Quercetin | 1.09 ± 0.001 | 3.59 ± 0.01 | 0.304 |
| Kaempferol | 0.725 ± 0.044 | 10.4 ± 1.9 | 0.070 |
| Isorhamnetin | 0.707 ± 0.019 | 5.04 ± 0.49 | 0.140 |
| UDP-Galb | 37.2 ± 2.2 | 0.029 | |
a
Kinetic parameters were determined at pH 7.4 with the appropriate UDP-sugar (1.0 mM), as described in Methods. Only flavonols were accepted as sugar acceptor substrates.
b
100 μM quercetin was used as the sugar acceptor.