TABLE 3.
Kinetic parameters of GT MG517 for donor and acceptor substrates at pH 8.0, 35 °C
Conditions were as follows: 20 mm HEPES, 20 mm MgCl2, 20 mm CHAPS, 12.5 mm DOPG, [GT MG517] = 50–350 nm, at pH 8.0, 35 °C.
| Donor | Acceptor | kcat | Km | kcat/Km | |
|---|---|---|---|---|---|
| s−1 | μm | m−1·s−1 | |||
| Donora parameters | UDP-Glc | DOG | 0.27 ± 0.02 | 87 ± 16 | (3.1 ± 0.8) × 103 |
| UDP-Gal | DOG | 1.10 ± 0.06 | 234 ± 45 | (5 ± 1) × 103 | |
| UDP-Glc | MGlcDOG | 0.004 ± 0.001 | <50 | >80 | |
| UDP-Gal | MGlcDOG | 0.030 ± 0.001 | 479 ± 50 | 63 ± 9 | |
| Acceptorb parameters | UDP-Gal | DOG | 1.13 ± 0.1 | 270 ± 90 (0.83 mol%) | (4 ± 1) × 103 |
| UDP-Gal | MGlcDOG | 0.023 ± 0.001 | ∼90 (0.3 mol %) | >30 |
a Donor parameters at 1.25 mm (3.7 mol%) acceptor (DOG or MGlcDOG, saturating).
b Acceptor parameters at 1 mm donor (UDP-Gal, saturating).