Table 5. Apparent steady-state kinetic constants of TmP2O wild-type and mutants with D-glucose or D-galactose as electron donor, and O2 (air) under saturation as electron acceptor.
| Enzyme variant | D-glucose/O2 | D-galactose/O2 | Substrate selectivity | Citation | ||||
| KM (mM) | kcat (s–1) | kcat/KM(mM–1⋅s–1) | KM (mM) | kcat (s–1) | kcat/KM(mM–1⋅s–1) | (kcat/KM)Glc/(kcat/KM)Gal | ||
| Wild type | 0.939±0.04 | 48.1±0.50 | 51.2 | 8.79±0.54 | 2.51±0.05 | 0.286 | 177 | [32] |
| H167Aa | 5.97±0.37 | 2.06±0.03 | 0.35 | n.d. | n.d. | n.d. | n.d. | |
| H450G | 0.987±0.05 | 12.5±0.15 | 12.7 | 2.45±0.12 | 3.51±0.04 | 1.43 | 9 | [32] |
| V546C | 3.06±0.14 | 88.6±1.30 | 29.0 | 46.2±3.21 | 6.57±0.15 | 0.142 | 210 | [33] |
| H450G/V546C | 2.43±0.14 | 16.8±0.27 | 13.5 | 12.0±0.38 | 5.92±0.05 | 0.493 | 27 | [32] |
| T169G | 0.69±0.11 | 0.26±0.01 | 0.38 | 2.48±0.94 | 0.27±0.02 | 0.11 | 3.5 | [34] |
| T169G/V546C | 0.44±0.02 | 0.43±0.01 | 0.99 | 0.40±0.09 | 0.38±0.01 | 0.94 | 1.1 | [33] |
a
Since H167A was not designed to specifically improve galactose turnover, but to slow down flavin reduction during the reductive half-reaction, the kinetic constants for H167A were not determined. The mutant was included since it is a close structural mimic of the wild-type when sugar binding is concerned. Its purpose is therefore mainly for structural comparisons.