Table 2. Kinetic constants of wild-type enzymes and selected variants toward galactomannan, mannohexaose (M6) and mannopentaose (M5).
| Galactomannan | M6 | M5 | ||||
| Enzyme | KM (mg.ml−1) | kcat (min−1) | k cat/KM (mg−1.ml.min−1) | k cat/KM (mg−1.ml.min−1) | ||
| PaMan26A wt | 2.4±0.3 | 3356±159 | 1413±155 | 7.6×105 | 3.8×105 | |
| 26-P140L/D416G* | 2.1±0.2 | 3860±80 | 1849±148 | 1.0×106 | 7.8×105 | |
| PaMan5A wt | 11.5±1.5 | 1674±138 | 147±19 | 3.0×106 | 9.2×105 | |
| 5-V256L/G276V/Q316H | 7.8±1.6 | 1493±167 | 197±38 | ND | ND | |
| 5-W36R/I195T/V256A* | 16.2±2.5 | 4199±438 | 263±41 | ND | ND | |
| 5-K139R/Y223H* | 6.7±0.5 | 1655±60 | 248±17 | 2.7×106 | 6.8×105 | |
| 5-G311S* | 1.5±0.4 | 1781±134 | 1247±292 | 3.4×106 | 1.2×106 | |
The kinetic parameters were determined at 40°C in sodium acetate buffer 50 mM, pH 5.2 as described in the Methods section. Paired t test was used to compare the kinetic parameters of mutants versus native enzyme. The difference was considered statistically significant when p<0.05 (*). wt, wild type.ND: not determined.