TABLE 4.
Kinetic parameters for wild-type and variant acetate kinases assayed in the direction of propionyl phosphate and butyryl phosphate synthesis
| Enzyme | Propionate
|
Butyrate
|
||||
|---|---|---|---|---|---|---|
| kcat (s−1) | Km (mM) | kcat/Km (s−1 mM−1) | kcat (s−1) | Km (mM) | kcat/Km (s−1 mM−1) | |
| Wild type | 218 ± 15 | 14.4 ± 1.4 | 24 ± 5.4 | 0.18 ± 0.016 | 39 ± 13 | 0.005 ± 0.002 |
| Val93 Ala | 1,029 ± 45 | 6.2 ± 0.9 | 165 ± 25 | 42.4 ± 9.0 | 33.4 ± 3.5 | 1.26 ± 0.3 |
| Val93 Gly | 840 ± 3 | 25.0 ± 0.6 | 33.6 ± 0.8 | 294 ± 21 | 63 ± 6.0 | 4.6 ± 0.3 |
| Leu122 Ala | 6.7 ± 0.3 | 10.7 ± 1.4 | 0.63 ± 0.09 | NDa | ND | ND |
| Phe179 Ala | 0.37 ± 0.01 | 11 ± 0.8 | 0.033 ± 0.003 | ND | ND | ND |
| Pro232 Ala | 8.5 ± 0.3 | 46 ± 3 | 0.19 ± 0.01 | ND | ND | ND |
a
ND, activity was below the detection limit (change in absorbance at 340 nm of <0.0001 U/min).