Table 3.
Michaelis-Menten constants.
| Enzyme | KM (mM) | kcat (s-1) | kcat/KM (s-1 mM-1) |
|---|---|---|---|
| pNPGlc-hydrolysis | |||
| Wild-type | 0. 24 ± .04 | 485 ± 31 | 2000 |
| N221S | 0.43 ± 0.11 | 1170 ± 152 | 2720 |
| N221S/P342L | 0.89 ±0.19 | 1710 ± 237 | 1910 |
| N221S/P165L/M278I | 0.66 ±0.18 | 1070 ± 171 | 1630 |
| F219L/K214R | 0.24 ±0.04 | 594 ± 36 | 2510 |
| F219L/P165L/M278I | 0.18 ±0.006 | 253 ± 3 | 1440 |
| G222Q/V203M/K214R | 0.10 ± .008 | 154 ± 3 | 1470 |
| G222Q/P165L/M278I | 0.27 ± .05 | 181 ± 15 | 678 |
| G222M | 0.17 ±0.03 | 254 ± 16 | 1470 |
| Q4'-hydrolysis* | |||
| Wild type | 0.06 ±0.03 | 7.2 ± 1.2 | 122 |
| N221S/P342L | 0.02 ±0.015 | 6.2 ± 0.95 | 281 |
| Q3-hydrolysis* | |||
| Wild type | 0.13 ±0.06 | 7.2 ± 1.8 | 55 |
| N221S/P342L | 0.05 ±0.02 | 7.1 ± 1.1 | 154 |
*Data from Lindahl et al [17].
For pNPGlc hydrolysis measurements were made at pH 5.6, 80°C, and for the quercetin glucoside hydrolysis (wt and one mutant) at pH 5.0, 90°C.