Table 2.
Effect of mutations predicted by molecular modeling on the activation of the sweet taste receptor by neohesperidin dihydrochalcone (NHDC) and aspartame (ASP)
| variant | NHDC EC50 (mM) | NHDC maximal signal (% of wt) | ASP EC50 (mM) | ASP maximal signal (% of wt) |
| wt | 0.1 ± 0.06 | 100 | 1.3 ± 0.1 | 100 |
| S620A2.57 | 1.3 ± 0.5 | 55 ± 80 | 1.2 ± 0.3 | 64 ± 4 |
| V621L2.58 | n.f. | --- | n.f. | --- |
| V621I2.58 | >1 | 60 ± 14 | 1.9 ± 0.4 | 61 ± 1 |
| F624L2.61 | >1 | 35 ± 70 | 1.4 ± 0.2 | 21 ± 4 |
| Y699L4.60 | 0.7 ± 0.1 | 83 ± 40 | 1.6 ± 0.4 | 78 ± 9 |
| Y699F4.60 | 0.6 ± 0.4 | 72 ± 17 | 1.2 ± 0.3 | 56 ± 2 |
| T724L5.37 | 0.5 ± 0.3 | 58 ± 60 | 1.5 ± 0.2 | 69 ± 2 |
| R725M5.38 | 1.3 ± 0.4 | 64 ± 14 | 1.5 ± 0.7 | 56 ± 1 |
| S726A5.39 | 0.9 ± 0.3 | 60 ± 50 | 0.9 ± 0.3 | 50 ± 2 |
| L800F7.38 | 0.2 ± 0.1 | 91 ± 70 | 1.2 ± 0.3 | 90 ± 1 |
| C801I7.39 | 1.6 ± 0.7 | 70 ± 13 | 1.2 ± 0.5 | 50 ± 9 |
| C801L7.39 | n.f. | --- | n.f. | --- |
| G804A7.42 | 1.3 ± 0.5 | 53 ± 10 | 1.6 ± 0.2 | 44 ± 1 |
| G804V7.42 | n.r. | --- | 1.3 ± 0.3 | 21 ± 2 |
Receptor variants that affect the NHDC response are shown in bold. Values are given as average over at least three independent experiments ± SD. n.f. no response to any tested sweetener, n.r. no response to neohesperidin dihydrochalcone up to highest tested concentration (6 mM), but responses to other sweeteners. (>), EC50 not calculable because saturation is not reached (Additional file 2).