Table 1.
Steady-state kinetic data for turnover of compounds by AmpD, AmpDh2 and AmpDh3.a
| Enzyme/Compds | Km (mM) | kcat (s−1) | kcat/Km (M−1s−1) | |
|---|---|---|---|---|
| AmpD | 4 | 2.0 ± 0.1 | 24.2 ± 3.5 | 12100 ± 1800 |
| 5 | 1.2 ± 0.3 | 39.8 ± 3.1 | 33200 ± 7500 | |
| 6 | 1.9 ± 0.2 | 47.5 ± 5.5 | 25000 ± 4600 | |
| 7, 8, 9b | - | - | - | |
|
| ||||
| AmpDh2 | 4 | 1.5 ± 0.2 | 0.20 ± 0.02 | 130 ± 17 |
| 5 | 4.6 ± 0.5 | 20 ± 1.9 | 4300 ± 790 | |
| 6 | 1.9 ± 0.2 | 0.18 ± 0.02 | 95 ± 14 | |
| 7 | 1.5 ± 0.1 | 51.8 ± 8.9 | 34500 ± 4300 | |
| 8 | 1.8 ± 0.3 | 73.6 ± 5.3 | 40900 ± 6800 | |
| 9 | 1.4 ± 0.2 | 1.6 ± 0.2 | 1100 ± 150 | |
|
| ||||
| AmpDh3 | 4 | 3.2 ± 0.5 | 17.9 ± 1.3 | 5590 ± 610 |
| 5 | 4.5 ± 0.6 | 70.6 ± 6.6 | 15700 ± 1900 | |
| 6 | 1.4 ± 0.1 | 20.6 ± 1.9 | 14700 ± 1600 | |
| 7 | 2.2 ± 0.3 | 195 ± 24 | 88600 ± 13600 | |
| 8 | 1.4 ± 0.2 | 212 ± 19.3 | 151000 ± 20500 | |
| 9 | 2.4 ± 0.3 | 85.3 ± 10.2 | 35500 ± 4800 | |
a
The activities of all three enzymes decreased in the presence of EDTA, indicating that they are zinc proteases. Kinetic measurements were performed in the presence of 100 μM ZnCl2 as a supplement for AmpDh2 and AmpDh3.
b
No measurable activity was detected for AmpD with these compounds.