Table 1. Enzyme kinetic parameters for the hydrolysis of p-nitrophenyl β-glycosides catalyzed by the wild-type and mutant Sfβgly proteins.
| NPβfuc | NPβglu | NPβgal | |||||||
| Enzyme | K m (mM) | k cat (min−1) | k cat/K m (min−1.mM−1) | K m (mM) | k cat (min−1) | k cat/K m (min−1.mM−1) | K m (mM) | k cat (min−1) | k cat/K m (min−1.mM−1) |
| wild-type | 0.37±0.02 | 0.408±0.006 | 1.10±0.01 | 4.1±0.2 | 0.70±0.01 | 0.17±0.01 | 4.2±0.2 | 0.025±0.003 | 0.0060±0.0008 |
| K49A | 0.81±0.07 | 0.65±0.01 | 0.80±0.06 | 3.1±0.2 | 0.283±0.008 | 0.092±0.008 | 7.7±1 | 0.031±0.002 | 0.0040±0.0006 |
| W54A | 1.97±0.08 | 0.0530±0.0008 | 0.027±0.001 | 7.3±0.2 | 0.0279±0.0004 | 0.0038±0.0001 | 2.2 ±0.1 | 0.00073±0.00001 | 0.00033±0.00002 |
| M57A | 1.08±0.06 | 1.05±0.01 | 0.91±0.05 | 2.8±0.1 | 0.37±0.04 | 0.13±0.01 | 3.4±0.2 | 0.0266±0.0007 | 0.0079±0.0006 |
| P62A | 0.26±0.03 | 0.054±0.001 | 0.209±0.008 | 2.4±0.2 | 0.039±0.001 | 0.016±0.001 | 0.9±0.1 | 0.00195±0.00007 | 0.0021±0.0002 |
| F98A | - | - | - | - | - | - | - | - | - |
| N112A | 4.1±0.5 | 1.82±0.07 | 0.44±0.06 | 1.16±0.08 | 0.305±0.003 | 0.263±0.018 | 2.8±0.2 | 0.035±0.001 | 0.0125±0.0013 |
| W143A | 35±4 | 0.020±0.002 | 0.00057±0.00009 | 20±2 | 0.00124±0.00008 | 0.000062±0.000007 | 12±1 | 0.00026±0.00002 | 0.000022±0.000003 |
| P188A | 0.17±0.01 | 0.000239±0.000003 | 0.0014±0.0001 | - | - | 0.0000364±0.0000004 | 3.3±0.3 | 0.000237±0.000008 | 0.000073±0.000007 |
| G195L | 1.7±0.2 | 0.070±0.002 | 0.041±0.005 | 2.1±0.1 | 0.0404±0.0007 | 0.019±0.001 | 12±1 | 0.0113±0.0004 | 0.00094±0.00008 |
| Y196A | 2.7±0.2 | 0.205±0.006 | 0.076±0.006 | 10.2±0.6 | 0.115±0.003 | 0.0113±0.0007 | 13±1 | 0.0103±0.0004 | 0.00079±0.00006 |
| P203A | 0.87±0.08 | 0.215±0.007 | 0.25±0.02 | 50±5 | 0.52±0.04 | 0.010±0.001 | - | - | 0.00287±0.00001 |
| H223A | 0.90±0.06 | 0.23±0.01 | 0.26±0.02 | 5.7±0.5 | 0.025±0.00096 | 0.0044±0.0004 | 6.5±1 | 0.021±0.002 | 0.0032±0.0007 |
| P278A | 1.3±0.1 | 0.034±0.001 | 0.026±0.003 | 2.7±0.1 | 0.00250±0.00005 | 0.00093±0.00006 | 0.4±0.1 | 0.00058±0.00003 | 0.0145±0.0005 |
| P309A | 0.580±0.004 | 0.015±0.0002 | 0.026±0.001 | 1.9±0.1 | 0.0499±0.0009 | 0.026±0.002 | 4.4±0.2 | 0.0057±0.0001 | 0.00130±0.00008 |
| T398A | - | - | - | - | - | - | - | - | - |
| S445A | 1.30±0.09 | 0.39±0.01 | 0.30±0.02 | 1.58±0.07 | 0.317±0.003 | 0.200±0.009 | 5.0±0.3 | 0.46±0.01 | 0.092±0.007 |
| W452A | - | - | - | - | - | - | - | - | - |
| F460A | 9.1±0.5 | 0.046±0.001 | 0.0051±0.0003 | 58±11 | 0.013±0.001 | 0.00022±0.00005 | 11.6±0.7 | 0.00268±0.00008 | 0.00023±0.00001 |
- No activity.