Table 3.
IC50 and Ki values of tested HIPVs to DhelOBPs.
| Ligands | DhelOBP4 | DhelOBP5 | DhelOBP6 | DhelOBP14 | DhelOBP18 | DhelOBP20 | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| pH 7.4 | pH 5.0 | pH 7.4 | ||||||||||||
| IC50 | Ki | IC50 | Ki | IC50 | Ki | IC50 | Ki | IC50 | Ki | IC50 | Ki | IC50 | Ki | |
| p-Cymene | 13.0 ± 0.9 | 12.0 ± 0.9 | >50 | - | >50 | - | ud | ud | >50 | - | >50 | - | >50 | - |
| γ-Terpinene | 11.0 ± 0.3 | 10.1 ± 0.3 | >50 | - | >50 | - | ud | ud | >50 | - | >50 | - | >50 | - |
| Terpinolene | 15.7 ± 1.8 | 14.5 ± 1.7 | >50 | - | >50 | - | ud | ud | >50 | - | >50 | - | >50 | - |
| Fenchone | 23.8 ± 5.1 | 22.0 ± 4.7 | 47.4 ± 2.6 | 43.8 ± 2.4 | >50 | - | ud | ud | >50 | - | >50 | - | >50 | - |
| Camphor | 18.0 ± 2.4 | 16.6 ± 2.2 | >50 | - | >50 | - | ud | ud | >50 | - | >50 | - | >50 | - |
| Terpinen-4-ol | 27.8 ± 3.5 | 25.7 ± 3.2 | >50 | - | >50 | - | ud | ud | >50 | - | >50 | - | >50 | - |
| α-Terpineol | 10.4 ± 0.1 | 9.6 ± 0.1 | >50 | - | >50 | - | ud | ud | >50 | - | >50 | - | >50 | - |
| (-)-Verbenone | 23.1 ± 3.9 | 21.3 ± 3.6 | >50 | - | >50 | - | ud | ud | >50 | - | >50 | - | >50 | - |
Notes: IC50, ligand concentration displacing 50% of the fluorescence intensity of the DhelOBPs/1-NPN complex; Ki, dissociation constant (μM); ‘-’ indicated the binding affinities were too weak (IC50 > 50 μM) to calculate accurate Ki values; ‘ud’ indicated an abnormal fluorescence intensity (increasing) so that Ki values could not be calculated.