Table 1 Steady-state kinetic parameters of the hsNadE catalyzed reactions.
From: Different ways to transport ammonia in human and Mycobacterium tuberculosis NAD+ synthetases
Assay | Variable substrate | Fixed substrates | Km (mM) | kcat (s−1) | kcat/Km (s−1 mM−1) |
|---|---|---|---|---|---|
Glutamine-dependent reaction | |||||
NAD+ | NaAD+ | Gln, ATP | 0.26 ± 0.04 | 3.2 ± 0.1 | 12 ± 2 |
NAD+ | ATP | Gln, NaAD+ | 0.17 ± 0.02 | 3.79 ± 0.07 | 22 ± 2 |
NAD+ | Gln | NaAD+, ATP | 8.3 ± 0.6 | 3.72 ± 0.07 | 0.45 ± 0.03 |
Glu | Gln | NaAD+, ATP | 11.6 ± 0.7 | 5.6 ± 0.1 | 0.48 ± 0.03 |
Glu | Gln | None | 34 ± 6 | 0.18 ± 0.01 | 0.005 ± 0.001 |
Ammonia-dependent reaction | |||||
NAD+ | NaAD+ | NH3, ATP | 0.52 ± 0.04 | 23.4 ± 0.5 | 45 ± 4 |
NAD+ | ATP | NH3, NaAD+ | 0.22 ± 0.03 | 18.5 ± 0.5 | 84 ± 14 |
NAD+ | NH3 | NaAD+, ATP | 42 ± 7 | 20 ± 1 | 0.49 ± 0.08 |
