TABLE 3.
Kinetic analysis of ScAGal mutants
kcat values were calculated assuming a protein molecular mass of 52 kDa. ± refers to standard errors based on the curve fitting using Sigmaplot. Mutants D149A and D209A showed no measurable activity. Mutants Y232R and N252A were highly unstable and kinetic data are not available. NC means not calculable.
| PNPG |
Melibiose |
Raffinose |
|||||||
|---|---|---|---|---|---|---|---|---|---|
| Km | kcat | kcat/Km | Km | kcat | kcat/Km | Km | kcat | kcat/Km | |
| mm | mm | mm | |||||||
| MEL1 | 4.5 ± 0.7 | 286 ± 21 | 63.5 | 11.2 ± 1.1 | 193 ± 5 | 17 | 54.1 ± 15.5 | 46.8 ± 7.02 | 0.9 |
| A41Y | 3.7 ± 1.2 | 90 ± 16 | 24 | 5.8 ± 0.5 | 131 ± 3 | 22 | 87.9 ± 66.1 | 91 ± 39 | 0.8 |
| Y232R | NC | NC | NC | NC | NC | NC | NC | NC | NC |
| Q251A | 1.4 ± 0.3 | 170 ± 11 | 121 | 254 ± 60 | 113 ± 16 | 0.45 | NC | NC | NC |
| Q251W | 0.24 ± 0.03 | 16 ± 0.35 | 66 | NC | NC | NC | NC | NC | NC |
| N252A | NC | NC | NC | NC | NC | NC | NC | NC | NC |