Table II.
Kinetic parameters of wild-type MGMK and S37 mutants
| GMP |
6-TGMP |
|||||
|---|---|---|---|---|---|---|
| Km (μM) | kcata (s−1) | kcat/Km (s−1/μM) | Km (μM) | kcat (s−1) | kcat/Km (s−1/μM) | |
| MGMK | 59.02 (0.23)b | 20.8 (2.1) | 0.35 (0.033) | 171.5 (11.65) | 0.0074 (0.00055) | 4.3 × 10−5 (8.22 × 10−7) |
| S37A | 558.6 (18.37) | 0.64 (0.05) | 0.0011 (5 × 10−5) | ND | ND | ND |
| S37T | 381.7 (3.64) | 1.7 (0.09) | 0.0043 (0.00019) | ND | ND | ND |
| S37Y | 48.7 (0.26) | 2.35 (0.36) | 0.048 (0.0065) | ND | ND | ND |
ND, not detected.
aThe Kcat values were calculated using the equation Vmax = Kcat/[E] where [E] = total enzyme concentration and is based on one active site per monomer. Assay conditions are described in Materials and methods.
bStandard error mean.