Table 2. GDP-fucose/GDP dissociation constants of mutants compared with wild type enzyme.
| K d (µM)GDP | K d (µM)GDP-fucose | |
| Wild Type | 0.35±0.07 | 0.23±0.04 |
| R40A | 3.10±0.53 | - |
| N43A | 0.30±0.09 | - |
| F199A | 0.18±0.03 | - |
| R240A | nd | - |
| R240K | 61.2±10.5 | - |
| D242A | 0.09±0.02 | - |
| D244A | 0.10±0.01 | - |
| W245A | 1.60±0.40 | - |
| F261A | 0.12±0.07 | - |
| D309N | - | - |
| F357A | 26.9±5 | - |
The K ds were determined from thermodynamic relationships and the estimated errors were less than±24% in the majority of the cases. n.d. = not detected; - = not determined.