Table 4.
Kinetic data for the S. cerevisiae transporter Gal2 and P. chrysogenum PcAraT derived from uptake studies with 14C-labelled l-arabinose, d-glucose and d-xylose. Sugar transport kinetics were measured by uptake of 14C-radiolabelled sugars by S. cerevisiae DS68625, an engineered strain lacking the Hxt1-7 and Gal2 transporters, expressing either GAL2 or PcaraT
| Gal2 | PcAraT | |
|---|---|---|
| Km, ARA (mmol L−1) | 335 ± 21 | 0.13 ± 0.03 |
| Vmax, ARA [nmol (mg biomass)−1 min−1] | 75 ± 5.2 | 5.3 ± 0.2 |
| Km, GLC (mmol L−1) | 1.9 | – |
| Vmax, GLC [nmol (mg biomass)−1 min−1] | 26 | – |
| l-Arabinose transport inhibition by glucose | 85% | 63% |
| Km, XYL (mmol L−1) | 226 [20] | – |
| Vmax, XYL [nmol (mg biomass)−1 min−1] | 91 [20] | – |
| l-Arabinose transport inhibition by d-xylose | 29% | 22% |
Transport inhibition was determined at 50 mmol L−1 [14C] l-arabinose and 100 mmol L−1 of either d-glucose or d-xylose and expressed relative to the transport rate observed in the absence of d-xylose or d-glucose. Values are represented as average ± mean deviation of duplicate experiments. Graphs used to calculate kinetic parameters are shown in Additional files 3–6. ARA, l-arabinose; GLC, d-glucose; XYL, d-xylose; –, no transport