Table 2. Chemical Structures of Ligands Bearing a Positive Charge, Affinity and Functional Activities of C-Terminally Modified [Pyr1]-Apelin-13.
| compound no. | compound code | peptide sequence | Ki binding (nM)a | Gαi1 (nM)b | β-arrestin 2 (nM) (Emax%)c | rat plasma t1/2 (h)d |
|---|---|---|---|---|---|---|
| Ape13 | Pyr-R-P-R-L-S-H-K-G-P-Nle-Pro-Phe-OH | 0.7 ± 0.1 | 1.1 ± 0.1 | 40 ± 4 | 0.5 ± 0.1e | |
| ref | KT04-39 | Pyr-R-P-R-L-S-H-K-G-P-Nle-1-Nal-F-OH | 0.12 ± 0.01 | 4.4 ± 0.6 | 41 ± 4 | 0.4 ± 0.1e |
| 42 | SBL-AP-018 | Pyr-R-P-R-L-S-H-K-G-P-Nle-1-Nal-Phe(4-CN)-OH | 0.13 ± 0.02 | 0.4 ± 0.2 | 14 ± 5 (100%) | <1 |
| 43 | SBL-AP-019 | Pyr-R-P-R-L-S-H-K-G-P-Nle-1-Nal-Phe(4-CH2-NH2)-OH | 3.4 ± 1.0 | 2.4 ± 0.9 | 105 ± 39 (80%) | 1.0 ± 0.01 |
| 44 | SBL-AP-020 | Pyr-R-P-R-L-S-H-K-G-P-Nle-1-Nal-Phe(4-CH2-Gn)-OH | 4.6 ± 0.1 | 10 ± 4 | 423 ± 58 (59%) | <1 |
| 45 | SBL-AP-051 | Pyr-R-P-R-L-S-H-K-G-P-Nle-1-Nal-Phe(4-Gn)-OH | 7 ± 2 | 12 ± 5 | 303 ± 130 (67%) | <1 |
| 46 | SBL-AP-045 | Pyr-R-P-R-L-S-H-K-G-P-Nle-1-Nal-Tyr(O-4-NO2-Bn)-OH | 0.15 ± 0.004 | 0.9 ± 0.4 | 60 ± 5 (99%) | 5.4 ± 0.9 |
| 47 | SBL-AP-046 | Pyr-R-P-R-L-S-H-K-G-P-Nle-1-Nal-Tyr(O-4-CN-Bn)-OH | 0.12 ± 0.03 | 0.4 ± 0.2 | 28 ± 5 (99%) | 3.0 ± 0.4 |
| 48 | SBL-AP-057 | Pyr-R-P-R-L-S-H-K-G-P-Nle-1-Nal-Tyr(O-4-Bn-CH2-NH2)-OH | 3.0 ± 0.4 | 10 ± 3 | 324 ± 49 (80%) | 1.3 ± 0.1 |
| 49 | SBL-AP-058 | Pyr-R-P-R-L-S-H-K-G-P-Nle-1-Nal-Tyr(O-4-Bn-CH2-Gn)-OH | 1.1 ± 0.4 | 11 ± 4 | 275 ± 14 (54%) | 1.1 ± 0.02 |
| 50 | SBL-AP-047 | Pyr-R-P-R-L-S-H-K-G-P-Nle-1-Nal-Tyr(O-4-npropyl-NH2)-OH | 0.30 ± 0.08 | 1.2 ± 0.5 | 53 ± 2 (97%) | <1 |
| 51 | SBL-AP-048 | Pyr-R-P-R-L-S-H-K-G-P-Nle-1-Nal-Tyr(O-4-npropyl-Gn)-OH | 3 ± 1 | 1.4 ± 0.5 | 197 ± 18 (70%) | <1 |
| 52 | SBL-AP-021 | Pyr-R-P-R-L-S-H-K-G-P-Nle-1-Nal-Arg-OH | 1.2 ± 0.3 | 6 ± 2 | 116 ± 19 (76%) | <1 |
| 53 | SBL-AP-054 | Pyr-R-P-R-L-S-H-K-G-P-Nle-1-Nal-d-Arg-OH | 25 ± 5 | 10 ± 2 | 906 ± 229 (66%) | 2.8 ± 0.1 |
| 54 | SBL-AP-052 | Pyr-R-P-R-L-S-H-K-G-P-Nle-1-Nal-Lys-OH | 7.8 ± 0.4 | 14 ± 4 | 708 ± 185 (67%) | <1 |
| 55 | SBL-AP-053 | Pyr-R-P-R-L-S-H-K-G-P-Nle-1-Nal-hArg-OH | 3.2 ± 0.2 | 6 ± 3 | 412 ± 89 (72%) | <1 |
Ki was calculated from experimental IC50 values (the concentration of ligand that displaces 50% of radiolabeled [125I][Nle75,Tyr77]Pyr-apelin-13) using the Cheng–Prusoff equation.78 Values represent the mean ± SEM of two or three experiments, each performed in duplicate.
EC50 corresponds to the concentration of ligand that produces 50% dissociation of Gαi1 from the Gβγ subunits. All compounds showed an Emax Gαi1 > 99%.
EC50 is the concentration of ligand that produces 50% recruitment of β-arrestin 2 to the apelin receptor. EC50 values represent the mean ± SEM of three experiments, each performed in triplicate. All Emax values can be found in Table S2 in the Supporting Information.
Values represent the mean ± SEM of three experiments.
Reported in ref (50).