Table 1. Kinetic Parameters for the N-Acetyl Amino Acid-Stimulated ATP−PPi Exchange Reaction by the MBP−PhsA−His6 Protein in Its Apo and Holo Forms.
substrate | recombinant PhsA form | kcat (min−1) | Km (μM) | kcat/Km (μM−1 min−1) | relative activity of endogenous enzyme (7) |
---|---|---|---|---|---|
(±)-AcPT | apo | 87.9 ± 2.9 | 26.9 ± 2.9 | 3.27 ± 0.37 | 74% |
holo | 83.5 ± 2.0 | 23.7 ± 1.9 | 3.52 ± 0.29 | ||
l-AcDMPT | apo | 122.9 ± 2.9 | 198 ± 18 | 0.62 ± 0.06 | 100% |
holo | 124.7 ± 6.5 | 254 ± 44 | 0.49 ± 0.09 | ||
N-AcGlu | apo | 25.0 ± 1.1 | 349 ± 55 | 0.0717 ± 0.011 | 11% |
holo | 28.8 ± 1.5 | 493 ± 82 | 0.0584 ± 0.010 |