Table 3. Steady-State Kinetic Constants for Putative 5-Amino-6-(5-phospho-d-ribitylamino) Uracil Phosphatasea.
| substrate | kcat (s–1) | Km (μM) | kcat/Km (M–1 s–1) |
|---|---|---|---|
| d-ribitol-1-Pb | 1.8 ± 0.1 | 1030 ± 180 | 1.7 × 103 |
| d-ribitol-5-Pb | 1.5 ± 0.1 | 1080 ± 140 | 1.4 × 103 |
| 5-amino-6-(5-phospho-d-ribitylamino)uracilc | 0.016 ± 0.001 | 100 ± 10 | 1.6 × 102 |
a
Catalyzed hydrolysis of sugar phosphate at 25 °C and pH 7.5 (see Methods).
b
Substrate concentration were determined by full conversion of free phosphate catalyzed by EFI-501083.
c
Substrate concentration was determined by decrease in absorbance at 340 nm, indicative of NADPH oxidation (ε340 = 6220 M–1 cm–1) during the enzymatic synthesis.