Table 3.
Opioid receptor affinities and agonist potencies of alanine analogs of Dyn A(1–13)28
| Tyr1-Gly2-Gly3-Phe4-Leu5-Arg6-Arg7-Ile8-Arg9-Pro10-Lys11-Leu-Lys | ||||
|---|---|---|---|---|
|
| ||||
| Peptide | Affinity | Agonist potency | ||
| IC50 (nM)a | Fold decreaseb | IC50 (nM)c | Fold decreaseb | |
| [Ala1] Dyn A(1-13) | 1400 ± 210 | 519 | 750 ± 30 | 1070 |
| [Ala2]- ″ | 13.5 ± 0.4 | 5 | 104 ± 32 | 149 |
| [Ala3]- ″ | 21.5 ± 3.7 | 8 | 2.0 ± 0.3 | 3 |
| [Ala4]- ″ | 750 ± 35 | 278 | 700 ± 20 | 1000 |
| [Ala5]- ″ | 45.0 ± 1.1 | 17 | 14 ± 4 | 20 |
| [Ala6]- ″ | 19.2 ± 0.8 | 7 | 23 ± 6 | 33 |
| [Ala7]- ″ | 10.0 ± 1.2 | 4 | 19 ± 5 | 27 |
| [Ala8]- ″ | 0.3 ± 0.0 | – | 1.4 ± 0.1 | 2 |
| [Ala9]- ″ | 7.4 ± 0.8 | 3 | 5.5 ± 0.8 | 8 |
| [Ala10]- ″ | 3.8 ± 0.5 | 1.5 | 3.3 ± 0.7 | 5 |
| [Ala11]- ″ | 8.7 ± 0.9 | 3 | 7.6 ± 0.4 | 11 |
| Dyn A(1-13) | 2.7 ± 0.3 | – | 0.7 ± 0.1 | – |
a
IC50 obtained from radioligand binding assays using[3H]etorphine in rat brain homogenates.
b
Compared to Dyn A(1-13).
c
IC50 obtained from the GPI assay.